Setting pump primary timing by milli volt method.
 

Sorry guys it was my brother in laws old Jetta.
He had just installed a used pump.
But the principal remains the same.

Decided to set for average hottest burn.

So read all glow plug voltages combined by reading the general harness.

Was 15mv he had the pump set by ear.

Loosened and tapped pump until hit maximum point of 36 mv.

Did not expect that large a voltage swing and it surprised me a little.

Also read three other Volkswagens on the property, two were reading 15-20 Milli volts and one was 66 Milli volts.

Do not know if the wide variance was newer glow plugs or older plugs.
Was not leakage from the relay as with key on and engine not running there was almost nothing read on harness of the high reading car.

These three were not adjusted but just was curious about what would be read from them.
It is obvious there will be no standard values and it does not really matter.
Went a little past with voltage tapering off on the one I was adjusting.. Reset to 36 mv.

Told him that since his injectors had never been checked there was a possibly the average highest readout would probably be the best.

Better than setting to one unknown injector at least.
No noticeable pre-ignition was present after or before the adjustment.

He changed the pump out because of fuel leakage not general performance issues.
Just told him to see if mileage was normal as well as performance as he like myself has been driving old diesel Volkswagens for years.

What I would like to have done is check the timing by the conventional method to see how it stacked up.
Just decided to see how it works out instead.

Mileage and smoking should confirm if it really is in the ballpark in a few weeks.

Garage cost to set pump timing is about 240.00 average here as you require an adapter to screw into the pump as well as a dial gauge to get the readout.

If he has no problems with it's setting might do it the conventional way to establish if to design accuracy.

Also a possibility the Milli volt is a better setting that the factory recommended now exists as it does deal with aging symptoms of many forms where the factory method does not.
It will take time to prove that though.

Have to wonder how close it is though.
Again more has to be known but my first thought is how quick and painless it is to do.
If a scribe mark was put on any pumps present position and it moved to the highest voltage reading nothing would be lost by trying it that I can think of.
You could always return your pump to where it was.

Now hoping someone out there will time with the drip method and just do a simple comparison by marking the highest voltage point read before and scribing a mark.

If you do the drip method right after that and they turn out exactly the same then for practical purposes this will be the better, quicker, and perhaps more accurate way to time the 123 engines.

Again a little more feedback will and should be generated.
Two noticeable items were the quick response or voltage change when tap adjusting.
Almost instantaneous for practical purposes and how such a little tap was changing the voltage.

My two cents for what it is worth.:)
Not meant to be a suggestion of validity by any means just a description of what transpired.

Gathered a crowd of guys and the first common observation was the speed of the process if valid.
Five minutes can reset a Volkswagen pump from start to finish with the accuracy of the procedure still unknown.

.

Barry I encourage you to continue to share your 'adventures of the glow plugs'. I find this subject more interesting than a hungry dog at a chicken bar-b-que. :D

Hopefully in time I can add my experiences when I get a good DVM.

Mike

Just got home from a meeting about 75 miles away this evening.
On way home I decided that I might do the car I am currently driving daily, another Volkswagen unfortunately.

This is based on my knowing the results faster than my brother in laws car.
Have suspected my car of being off a little pump-wise for quite awhile now.

Anyways will be able to post in about a week the changes in mileage if any plus driveability as it is a little sluggish compared to most I have owned.

This Milli volt method is used by the factories to set some pumps to engines for quite awhile, so am starting to think it has general application potential and if it proves so over the long-haul, it will mean a lot more pumps get set as the procedure is so fast and simple.

We will see if there is any downside soon.

Needless to say I will scribe my pump to flange just in case I have to find my way back to the original position in a week or so.

A true case of nothing ventured, nothing gained.

Also the fuel mileage on this example is about 5 miles per gallon substandard.

Plus I seem to have my foot a little more into it for highway cruise.
So there is justification in trying it out in my opinion.

Will give an extensive report in about a week or less.
Who knows?
Perhaps I will not have to buy fuel anymore and the ball joints will self rejuvenate as well. :D

.

Keep up your interest in this Barry...
 

you strike me as being firmly based in objectivity and scientific methodology.

Related Sidebar - Right now I'm working with my small local independent M-B shop and have convinced him to invest in one of the pulse sensors that interfaces with an inductive timing light... this to more quickly check IP timing. And now if your method of using mv readings off of the #1 glow plug proves to be valid, this would be an outstanding adjunct to our fast timing check.
Questions:
Q1 - Do you think there is a way to attach a long, heavy, bar to these IP(s)... such that one could more easily/accurately shift the IP body and its timing? If so, this would go well with your method of reading the glow plugs for the highest mv readings!
Q2 - What if you install a brand new glow plug in the #1 pre-combustion chamber just before warming up the engine and taking the mv readings and/or making adjustments? Wouldn't this likely give you more consistent results?
Sam

What generates the voltage? The dissimilar metal of the heater bonded to the case, and the hotter temperature where this bond is at the tip? That would be my first guess, but it's just that.

As of one hour ago it is no longer theoretical.

My brother in law and myself did my own car as well.
There was a complicated peak reading of about 1/2 of a Milli volt greater than our start point perhaps less than an 1/8 of an inch from the original pump setting away.

One immediate change was a small puff of black smoke that was very small when quickly opening pump linkage from idle.
Brother in law said that is an indication of peak possible pump timing point rather than a new problem.

He does work on a lot of Volkswagen diesels.
Took car for a drive after finding it started quite a bit quicker as well.
Much more power than having foot into the pedal.
Not subjective but a absolute highly noticeable difference.

Now the voltages and observations.

We did this one from the value of all plugs still linked together.
Start voltage was a floating thirteen Milli volts.
As we moved the pump the voltage average started upward a little till average of 13.5 Milli volts was reached before going past it and voltage dropping off.

Reset pump to our punch marks and did it again.
Same basic results so locked pump down at that 13.5 average.

I do not need a week to find out as the improvement is major in nature. We will see about the fuel mileage but even if no change I want this setting over any other.

Car kind of floats along now where I had to kind of force it a little to perform.
Also it wants to rev not only easier but with a lot more apparent power.

We will do a few more early next week as brother in law thinks my results where better than the manufactures recommendations could accomplish.
He said he has only seen a few set by the manufactures specifications give that slight puff and he does a lot of those engines.

We were also getting voltage change when there was no visual obvious moving of the pump other than a light tap being applied.

Now the downside although minor.
It appears to minimize the voltage hunting effect over about 0.4 Milli volts, that a condenser will have to be inserted across the test meter leads to establish an automatic average to further speed up the process, plus eliminate the mental gymnastics of establishing the average float values.

If similar results are obtained on the next six cars lets say and any complications noticed and rectified.
It means we have a vastly superior method of timing the pumps to our engines in sight now as really think it is far more accurate than a drip or well up test.

This method automatically seems to compensate for existing deficient problems that are inherent to quite an extent in older engines within sensible limits.
The other systems that I am aware of do not.
In other words if you where to take your car to Mercedes to have the timing checked my guess is other than a new engine the true optimum setting will not be there when you pick up your car and even on a new engine it may not still be there.

But before getting totally carried away we have do do some more cars and get rid of the hunting effect of the meter that we experienced on my car, yet was not apparent on the one we did yesterday or to a much lesser degree.
I do not know what the hunting effects indicate as have not had time to reflect upon it but they might have some significance.

Idle sounded very good and smooth so do not think pump is over advanced either, although with the power one might almost think it is.

So far so good but it is important to realize until we get about a dozen cars done we will not be absolutely sure this is going to replace the older methods.
At this point I think there is a very good chance it might transpire though because it is physically impossible to get such small movements of the pump with hand manipulation, plus you are almost guessing about the actual instance of when the wellup occurs or drip is absolutely right.
At that point of pump adjustment all you have really accomplished is making the injector spray into the cylinder at a given point in relation to the crank.
No compensation whatever has been done to allow for slightly out of value components basically.

Perhaps one could say the old method is crude by comparison.
Will stop droning on now until we do a few more cars.

Still looking for any downside indications by keeping an open mind.
Am almost certain now they are not there.
Just thought the meter instability to some extent that appears to be hunting might be the meter itself, will have to check that out.

As for his car that he changed the pump on that had a large leak in it.
The one we timed yesterday in fact.
He thought the basic problem was caused by the old pump.
Turns out the engine block was not in good enough shape for really any meaningful interpretations.
So I am discounting it from the test other than that apparent massive peak of 36 Milli volts it topped out at.
Also do not know the reason why that peak occurred at that magnitude.
Well away to the beach for the weekend hopefully but since I may have to come back to town for parts as the well malfunctioned last week I will check this site.

This is no longer a joke as it really appears to work.
This is also a dynamic test that is being conducted under operational conditions, Not a static test.

.

Guess I will try to answer a couple of questions after some thought.

As I mentioned the adjustment of the pump seems to be so fine that a long leverage bar may or may not allow the incremental movements required by this system.

As for going off of the first glow plug that is OK if you know your injector is popping off at factory recommended values.
By using the reading from all plugs simultaneously it will give an average value of all injectors and cylinders combined.
In other words a more accurate result on older engines.
Also do not forget you are doing a dynamic test with the engine running.
This has to be better than the static mechanical test.
You are also tunning for the absolute power peak.

My next concern is if that is also the best fuel economy point with this procedure, if not perhaps the timing may have to be set a little before the absolute peak on the retard side.

Since my accumulated mileage is only 75 miles on my old Jetta I have no way of estimating fuel consumption yet.
The thought is that most 123 owners especially 240d owners will want the peak setting versus the highest possible mileage setting.
If the two settings coincide it would be great but life being what it is may not be so.
Forget engine sound at idle as well.
This system is so fine you will not notice any difference with the idle after you get close to the final point.

As for the gentleman that asked the function of the dissimilar metals in the plug that generates higher voltage with more heat.
I really do not know exactly how the glow plug is acting a little like a thermocouple exactly.
Also still have some questions why some read higher that others.
But at this early stage do not feel it is of any recognizable importance.

Just too early yet to make any absolute conclusions about anything.
Interest will only build once it is proven totally to be of benefit to 123 diesel engines.

There is not too much doubt today in my mind that it is a good and workable procedure for the older 1.6 Volkswagen diesels.
All brands of indirect type diesel engines with glow plugs will probably respond in the same fashion.

This is also a simple procedure that is well within most site members ability to preform.
That was one thing that I was really thinking about before getting into it awhile ago.
Plus as long as you take a pin punch and mark the pump flange and the pump mount flange so you can always go back to those marks I felt it almost foolproof.

As I stated if the procedures to use the glow plugs in many ways as a service tool providing all the initial responses are positive.

It will still take a year or so for acceptance and I personally know that many questions and issues will arise in many peoples minds as this is explored.

If you want your car to perform to it's maximum ability do you really have any other choice other than trying to set the pump and fine tune it many times by driving and adjusting many times and still you might miss the sweet spot.

The factory drip or well up position will in 9 out of 10 cases not be the best pump timing position on older engines in my opinion.
The factory position will be okay probably but just not the optimum possible position.

Just keep an open mind as there may still be a downside that arises yet.
Well back to the beach as have gathered up the last of what I need for the repair out there. :)

.

Barry,

I have been reading your threads for a while now and have tinkered with this operation and now have some questions.

If you dont remember I was the second individual who had fooled with the fuel elements (because the rubber o-r ring was leaking). I had moved the first and second elements on a five cylinder.

I finally got a good enough mulitester that can accuratley read mV to a .1 level, so I attempted the operation today. After the car was fully warmed up i measured all glow plugs (disconnected from the wiring of course) and the readings were about 12.3 mV for the # 3,4, & 5 injectors. #1 was about 10.8 and #2 was about 11.6. The problem I had was that in taking these readings the numbers were jumping around everywhere and the measurements I took were (what you would have called) "floating". I noticed that by twisting the elements clockwise the the voltage for the respective glowplug would go up. But here is the problem.....I noticed that if I would raise the volatage for the #1 cylinder, the voltage for #3 would go down. I believe it started throwing off other cylinders as well.

My thinking is that this is the result of the Inj. Pump. is not being properly timed to the engine. Should I do this first before i retry the mV method? I got horribly frustrated today in my attempt. I dont have a drip tube, but I thought I might use this method: http://diymbrepair.com/easley/iptiming.htm

Also I should be recieving a new rack damp. pin tomorrow or the day after. should Install this before I attempt all of this or will it affect it at all.

Thanks for all your help barry

I would think that to be normal governor behavior. If you increase the fuel delivery of a cylinder to make it hotter, the governor will keep idle speed
constant by backing off the rack, lowering fuel delivery to all cylinders.

I really don't recommend adjusting the individual delivery valves without putting the pump on a test stand.

Mitch is right of course.
This method is to be used only when pump needs a shop sequential timing because a person has accidentally modified the element positions.
The pump is only going to the shop anyways and what you do if not successful does not increase their charge either.
There is no sense in setting the pump primary timing right now.

For one thing the drip and welling up are in reference to number one element and you know it is off.
Only way you could do it is to isolate the harness to 3,4,and five cylinders and use millivolt method.
But not required anyways right now.

It does take two sets of hands to really manage what you are trying or two meters for one person to try.
Every time you change the setting of one element of course your reference voltage is going to change.
Since cylinders 3,4,& 5 are the same any one can be used as a reference by adjusting the element # 1 or 2 a little higher in voltage, then go right back to see what it has done to your reference cylinder voltage.

You are trying to get them to read the identical same output voltage.

Now for the hunting that is hard to work around.
I will go experiment and deal with the problem as a time constant kind of thing today as I do not think it is an inductive problem.
Suspect we will have to just put a capacitor across the meter basically to average our Milli volt swing.
Will try to do that today and get back.

Do not get particularity frustrated.
Look at the bright side you are already getting a solid indication that one and two are off pretty bad.

Also my old Volkswagen did get back the missing 5-6 mpg as I drove it 400 miles in the last couple of days to the Willie Nelson concert, and on many trips back and forth to town from the cottage to get every last part to get the water well up and running.

Will drop a message as soon as possible.:)
Also look at the upside.
As we jointly work through the thing your knowledge is going to increase.
That way If I am swamped with alligators at my end guess who I can refer people to.

.

hunting meter.
 

Okay.
I built a little time constant circuit from a 3300 microfarad capacitor rated at 16v, and a resistor of about 700 ohms value.
Just stuff laying around.
Worked fine at stabilizing the readings.
The way it is wired is the resistor is in line with the probe and the capacitor is across the negative and positive terminals of the meter anywhere past the resistor towards the meter.

The condenser is still subject to the hunting but acts like a battery to automatically average the readings.
Last digit of my meter stayed still at a constant reading unless the primary reading average value changed of course.
Then the meter just went to the next number higher or lower in a rock stable fashion.
Values for those components are not critical or expensive either.

Clear as mud?
If you have any questions just ask, that is the only way we will ever succeed.
I will try to support anyone that tries needless to say.

Now I know you can get those two out of calibration injectors back in line.
I could do the mental gymnastics easier with the hunting meter perhaps.

The other day I also realized the hunting was also a major distraction.
Distractions tend to affect accuracy.
Keep going and at any point if you feel frustration drop me a line.

You are going to succeed at this.
Also remember as one person mentioned your actual movement of the element is going to be very small.
Do get a friend to move the voltage probe to what you want to read while you are adjusting the first two elements.
Really almost a two person job.
There will be a lot of back and forth with the probe until you are really close. :)

I really believe you can pull this off then perhaps it will be time to do the pump re-time.
The same voltage on cylinders 3,4 & 5 give hope the engine generally is in reasonable condition or better.

Sure it might be a little problem to locate a condenser either new or used and a resistor.
Any friend with an interest in electronics could help or even any electronic service shop.
These are cheap standard components.
Thinking a few dollars or free used parts.

Will mention although I think you already know not to move cylinders 3,4, & 5 elements position during this procedure.

.

Resistance Instead of Voltage?
 

Interesting stuff. I'm wondering if there is any merit / advantage to using an ohm-meter across the plugs during the timing process instead of a voltmeter? The plug resistance definately does change with heat, as that is what they're designed to do. However, as this thermocouple voltage effect seems to be an unsolved mystery and varies widely from one car to another (if I read all the above correctly), would resistance readings give more consistant results?

BTW, when I was in my teens, a long time ago, I worked summers at my uncle's Texaco. He had a contract with the city for maintenance on some of their Diesel powered machinery. I recall when he was setting the timing, he would watch the stack for the exhaust to make a black puff, then just go back from there a bit. I think they were mostly Detroit engines at that time.

Dave
Sackville, NB Canada
1976 300D

Dave, sure we should reset your pump since you are using vegetable oil exclusively.

Since the flame front is slower in my opinion a slight correction will help a little.

The amp meter use is an excellent thought but I kind of feel although we are generating voltage it may not be backed up by any ability to generate current to any extent.

Measuring resistance is not a good ideal as the source is generating voltage at the same time.

All ideas deserve looking at though and they should be raised.
Also as time goes on it will probably prove out that even if different cars generate different baselines it does not matter.
We are only seeking the peaks usually or trying to equal one voltage with another by direct comparison.
The amplitude just increases the percentage accuracy if it is an unexplained higher value.

One never knows until they ascertain the facts by trying.
Again as I have repeatedly mentioned pin punch mark the pump in it's present position before moving it means you can always go back or forward to your present timing if you fail somehow.

What I am still hoping is the hottest burn also coincides with the highest mileage point as well, if so when we work through the really small things like the floating voltage or hunting problem (solved this morning I believe). We are getting close to a tool that will replace what is presently done, and thought now and a cheap one to boot with enormous accuracy.

Time will tell now as the gentleman with the current problem is going to totally solve it in my opinion.
As long as he keeps an open mind and avoids frustration.
This is still new enough to cause application misunderstandings.
I would like to see every question raised and answered as we go along.

Still looking for the fatal flaw but the possibility of it existing is diminishing rapidly.
I imagine the definitive manual will be written in the next six months at the rate things are going.
Seems almost impossible for it to fall flat now.
We have to wait and see though.

The bulk price of vegetable oil in our area will take a little time to find out.
The price I think will be right but the quantity in those containers again may be a problem.
My son in law is dealing with the issue.:)

.

JMAN300Sd, I will try to address specifics to your inquiries.

You are a sort of test horse here as well.

Yes the voltage will change on numbers 3,4,&5 as you adjust the elements on 1&2.
That is to be expected and is the reason you want an extra set of hands there to monitor one voltage and then quickly check another as you move the element.
With the hunting stabilized to zero with the small circuit I mentioned it will be a lot easier for you.

What you refer as the floating will remain to some extent and is normal, it becomes much less of an issue with the hunting eliminated.

As you get closer and closer to the final position the floating as you describe will lessen.
The floating and hunting are separate things.
The floating is being caused by engine parameters being changed in some way by your application and is normal in my opinion.

.

Alright Barry...I think I understand you. I have still a few questions though as far as my procedure this afternoon:

Should I set the #2 element to the reference (#3, #4 or 5) first and before I do the #1 element?

then...

Should I tweak the #1 element in an effort to raise the volatages of the remaining elements as much as possible, even if it means reducing the voltage of the #1?

I assume after this point I would then go about timing the pump to the engine..Correct?

First thing is to get those two electronics parts to get rid of the hunting effect.

Call the assembly a voltage or voltage hunting stabilizer.

You will be amazed how the hunting or drift stops and the final digit remains stable.

Next is to start adjusting the number one or two elements till the voltage on one of them is the same as on 3,4,&5.
Of course as soon as you start to adjusting the number one or two element # 3,4,&5 will start to change their voltage as well.
Your object is to keep at it till both voltages are the same.

That is why a second set of hands is a good ideal.
He can read back and forth at your suggestion while you are adjusting the element.
As soon as that is done do your next element the same way it will be either #1 or #2 of course depending on which one you did first.

When all five voltages are equal your job is done.

Absolutely does not matter what your final number is only that they are all the same for practical purposes.

Of course do not adjust #s 3,4,&5 elements at any time.

When you have accomplished that then we can do the overall timing of the injector pump to engine.
If you feel you want to but may not even be required. :)

Ask for clarification of any thoughts you have.
I will try my hardest to deliver understandable answers. .
Edit: Just re read your post.
It does not matter if you go higher or lower in voltage to match the voltages of 3,4,&5.

The object is absolute here and that is to make 1 & 2 the same as 3,4,&5.
But do get the two electronic type parts and add them to simplify your job.

It's gone on so long now one or two days are not going to matter and I want you relaxed.

Also as we go along other people will be watching and learning something from your experience.

.

What does the glow plug voltage represent? Why do you try to set the highest value?

Highest combustion temperature is present at the highest voltage.

Fuel injected at that point or lets say the bulk of it should give maximum energy output to engine.
Or maximum utilization of fuel if lucky.
Certainly the most available power. :) Old 300d, this applies to the direct relationship of point of fuel introduction.

Not to be confused with what the gentleman is trying to accomplish with his pump out of sequential time.

Hope he ignores it for the time being.
Others may put it more succinctly.

.

Thanks, that's what i figured, but I didn't see it spelled out. Have to ask the obvious.

Old diesel, I am not a know it all.

Sometimes my answers will be wrong.
Why I hope this will totally work out is that I feel I should contribute something of some worth to the members that follow this site.

You have all freely given me so much.
I will in concert with others try to take this to the maximum practical applications.
It is the best potential thing to help people keep the ownership costs down and improve ease of service as information is gathered.
You also will not have to be a rocket scientist to apply it either.

What really concerns me is that I also have the faint outline of something else in mind not related to the above.
But might be practical as well.
Will have to wait to see how this goes first.
See many applications not even even mentioned yet for the millivolt system.

Right now it is gathering data and dealing with any modifications that are required plus supporting users that must have attention as they arise.
Every successful conclusion is going to give it a boost till it becomes the preferred method if possible.

Also it was only partially in jest.
A manual will have to be developed for complete utilization of the system down the road I think.
Right now we are just playing around the edges. :)

I'd like to see the timing that has the highest reading verified by checking it after the fact with the RIV tool to verify just what amount of advance was really achieved and how close it is to spec. That will give this method credibility. and back it up by doing the same on two other cars.

I'm interested in this myself. I might just give it a try on the SD with the RIV lights.

It's entirely possible that the current FSM spec is a compromise for emissions. Further advance of the injection timing might provide some benefits.

I wouldn't be surprised either to see an improvement by advancing the timing a little bit. Much of this may be due to the fuel. The current lower cetane fuel available these days is not what these cars were meant to run on. You may well find that the ideal setting depends a lot on the fuel used.

On the last two posts I already agree other than I am starting to suspect the optimum position is a little advanced over the factory recommended one.

This I thought might be because of aging of certain components to some extent.
Or perhaps because of todays fuel.

Brian's thought is good as well or perhaps Mercedes engineering just decided on an arbitrary broad production value. But one thing is certain if you reflect upon it.

The manufactures that are using Milli volts as a production tool to set up new engines must have covered this area and went with it as a preferred method for some reason.

At first I also thought it should duplicate the factory setting but now even wonder if that is a good thought or not.
The answers probably are going to become evident as more and more cars are done.

First downside is my clutch did not appreciate the boost in power.
The equation so far is quick timing change versus four hours for me to replace clutch when I get to it. .
The clutch is not totally gone yet but is showing symptoms of not liking the additional power.
There is also some hang up or feeling that the original timing marks are written in stone.

At the time these engines were made the engineers had no way of allowing for aging or tolerance differences so they would have been forced to strike a timing position that was a compromise even for new engines mind what the majority of us drive.

Anyways glad to see you keeping an open mind.
It's pretty lonely here.
I am not seeing any evidence that the engine is advanced too far.
Not even the slightest trace.

Will try to do two more Volkswagens this evening and post back.

Brian if you decide to try it out make sure you add the two minor electronic parts to your meter.
The hunting meter would have driven me crazy if I was not already there. :D
Just pin punch so you can get back to your original marks as well.
Thats primarily for mental security and ease of finding your factory position.
Make the marks good as you will probably never be going back.

It will be a constant reminder also of why in He** you ever had the pump timed there in the first place whenever you notice the marks. :D

At this point I should post that I will not accept responsibility for doors blown off or transmissions parts littering the road. :D
Neither am I accountable for less frequent fuel stops. :D
Sorry, just gotta have a little fun. :)

Now seriously, what is the downside Brian.
You find out your present timing you fairly recently set is valid for your individual engine? Even if thats all thats accomplished it is an indicator itself of what bonehead is curious about to some extent.

Ever wonder why a spread of about 5 mpg is reported by various 123 and 126 owners?
Very few also describe power and acceleration correctly but we all realize some cars of the same type are quite a bit quicker than others.

As for the higher than average mileage figures most of us put the reports off to not doing a valid procedure to verify it properly or wishful thinking.
Some 240d owners quote 30+ while the majority of us think about 25 mpg for most examples of 240ds.
I am not referring to ebay ads either or the figure would be 40+.:rolleyes:
Could that be the pumps are set at factory marks where the higher mileage ones had the pumps safely advanced by knowledgeable mechanics?
Is it not about time we found out?
The best way to help this site grow is to explore these things in a productive fashion.

Speaking for myself I have mastered the glow plug circuit I think and want to move on. :)
No that last statement is completely wrong!
I am still stuck there for awhile yet it appears.

.

well this will give us a basis of what actual degree of timing you end up with. Being that the RIV tool gives the most precise reading that is repeatible as well. we can reference it to a known accurate method of measuring actual timing. and see how far off it would end up and if there are wide swings between one vehicle or not. A good way to validate the results, and practicality of the millivolt method.

Barry, I presume that you used a digital meter and had trouble with the fluctuations of it. I've got a decent analog meter that can get down to very low voltages.........think I still need the capacitor for it? I'd be surprised if the meter can respond as quickly as the fluctuations.

Yep- from my days as a bench repair tech for the phone company, I always preferred an analogue meter for finding peak values- especially when close to the top of the peak. I think that preference is pretty universal among technicians.

BTW Barry- you're reporting doing a lot of VWs- For a Benz, how would you actually move the IP with the engine running?

Dave

Brian, for some reason the hunting is not fast really and the analogue meter might or might not follow it.

Hopefully the internal delays with the analogue meter will average it out but if not the capacitor and resistor are quick to add and not critical at all.
The input impedance of your analogue might also be a factor, we will see.
Needless to say make sure you do not expose that meter to glow plug activation voltage while in the Milli volt range.

I do not want to get too technical but the hunting should not be there in the first place in my opinion.
I only gave casual consideration of why it was occurring until the other gentleman mentioned he had it as well.
Have not given it much thought yet as it has no impact on what we are doing right now.

The hunting spread seems to remain over about .5 or .4 Milli volts.
Very consistent and moderately paced.
I had to always calculate the mean average while underway.
Right now I do not have the time to do a serious evaluation but am aware it is not just a spurious effect.
Something is really going on.

As bonehead suggests results are important.
I do respect his ability as well.
At present I feel we will never have an optimum timing number for these older engines.

It will seem we are going to be treating each one a little differently because of so many variables.
We should almost just think of it as custom timing.
My initial concern was that it would get into pre-detonation but surprisingly enough no evidence at all yet.

I hate doing assumptions but suspect the closer an engine is to new condition the less gain will be evident.
Even that may be wrong.
Could be the inverse.
It is still very early.
It may not have any value at all.
Intuitively I feel the potential is there though.

Something wild to finish this note with.
I thought the meter was getting inductive pulses for a moment and was counting them.
Was going to grab a scope and take a look at that harness.

Better to leave certain aspects to better minds and save my energy until someone reports something tangible that has to be dealt with as it is probably coming.
The next one is not likely going to be as easy to solve.

We as a group may never get by it either.
On the other hand it may not be lurking.
If we get past the preliminary stages of this procedure it might be interesting to investigate that apparent voltage instability further.
I really suspect it just reflects the difference between a hot glow plug and perhaps the plugs reaction while under the presence of the flame front.
But have no reason to buy that at this stage.
Any thoughts?.

.

Coldwar, for Volkswagen just loosening the mount bolts a little and tapping the pump with a wooden block and light hammer taps seems to do it.

I do not know how to describe the strength of tapping other than it depends on the leverage axis on the type of pump you are adjusting and you might feel better with a pry bar used reasonably...

I assume the worst probable senario is the pump would turn to the adjustment stop limits if the bolts were too loose and the hard line resistance was overcome by the engine.

I wish I had done a Mercedes pump so I could answer this better.
Guess after all is said and done you loosen the mount fastenings until you can budge by tapping or levering the pump.
Probably have to start and stop the engine a few times to find that situation.
You do not want to loosen more than required.
Yet you have to be able to move the pump a little with reasonable force.
You cannot make it loose enough to turn by hand in my opinion.

.

Small item to report.

As the mileage builds have been watching for any additional heating effect.
Yes the engine is far more efficient but have decided since it burns a good 10% less fuel that is compensating for the period of hotter burn that is possibly of shorter duration.

Equaling a similar btu output perhaps.
I was concerned and thought if the injection was too early it would waste the heat by reflecting a warmer running engine.
I seem to be getting more fuel mileage than any I have ever had before and have had a pile of these.
Cannot pin it down yet for sure but the miles are building.
We did not do the two Volkswagens we were going to do today as other things arose.

Tomorrow might be a wash out as well.
Perhaps over the weekend may present a chance.
Will keep updating this thread as I still feel it is important.

.

Another good tip and enlightenment came from Coldwar via pm this morning.

Has Mercedes been holding out on us? Apparently he is under the impression that they have a special truss tool to hold and adjust the pump hopefully dynamically on 123s and he thinks he can duplicate it at home.

There goes the tap and wood block routine or pried pump.
Never really liked it anyways.
What if someone got overly agressive?

Why can I not visualize these things in advance?
Describing what I would do was a nightmare in comparison.
I will have a look under my hood as it has got to be a pretty simple tool or if he has a picture or drawing of it that may make it even easier.
It will not be rocket science either way. :)

Thanks Coldwar and when the price of vegetable oil starts it's upward spiral I have told the wife to blame you. :D

.

Yeah I told him about it. Its mentioned in the FSM and even gives its part number.

http://skinnerbox.steaky.org/Service/W123/w123CD2/Program/Engine/617/07_1-114.pdf

I have a thread at my site about fabricatining one for yourself in its early stages.

lot of flexibility in design...I don't like the original as it uses two head bolts to attach to the block. Id rather pick a different anchor point and make something simular in function.

There's an even better picture of it right here at Mercedesshop under Special Tools- Index #617-0721
Dave

Dave [ColdWar]...
 

I've been closely following this thread but I'm even more new to the Forum than you and I was not able to find what you referred to as having index "617-0721". What tha hay!
Can you give us novices a html link?:confused:
Sam

'Fraid not - the catalog loads inside a single html page so you can't post a direct link very readily. BUT if you look at the menu at the top of the page, you'll see a tab for "Special Tools." Click on that, then click on the CONTENTS link and go to page 28. Its the last entry on the page.

Design ideals are welcome for the adjustment jig.

The Mercedes service part is for adjusting injector pump timing with a running engine.

So far people like bonehead, dave and myself I believe are not really happy about having to remove two head bolts and use them for the mount like the factory one does.

Bonehead has been looking at home fabrication of one but his ideals are not set in stone either I believe.
I had a quick look but the first substitute I visualized almost seemed like a rube Golberg ideal unless a plate is made to sit over the head bolts and a method is designed to clamp or secure it there.
Should work if carefully though out.

Perhaps someone will have a better ideal.
Have a look at the factory part.
Then take a look at your engine bay.
Consider it a contest.
The winner gets a hard time.
Plus the questionable distinction of being caught up in the mess.:D
Also am I ever going to get it if all this does not a work out.:eek:

That thread will be far more interesting than anything so far.
In fact it should set record posts as all the current record holder did was install his pump 180 degrees out. :D
I guess I could leave the country.
Since I live in Canada perhaps that is already accomplished.:)
Anyways lets hear your ideals.
No I do not need a new therapist.
The present one is enough although getting no results apparently. .:)

.

For a contest, we'll all have to go Secret Squirrel, right? When device is successfully completed, post a pic and may the best man win!
(Me, I have no machining tools or skills whatsoever- it's all gonna have to fasten together from the junk bin. Should be interesting.)

you guys are getting almost "giddy"...
 

and that's a sure sign that we have stalled out our brains... so let this "nubie" ask a question or two and maybe get us back on a more productive track:

Q1 - Barry, was there a thread prior to the present [" Setting pump primary timing..." ]... another thread on this same subject?

Q2 - Barry, do I understand you correctly that to "average" the milivoltage of the engine's glow plugs you merely wire all of them together [parallel]?

Q3 - Barry, have you played around with the values for the capacitor and resister you used to stabilize your meter's readings?

Regarding Q2, I have found that I can use " banana plugs " to easily connect to all three of my M-B car's parallel glow plug system via the "female" plug on the line that plugs into the GP relays. The full-size " banana plug " used on my digital VOM connects very effectively into these multi-conductor inline harness plugs.

Sorry Barry, I'll read your threads no matter how stung out your writing might strike me ! Are you really seeing a "shrink" ?

Thanks Dave [ColdWar], I finally found the M-B "Tool" thingy you referenced. I'm still exploring the "Ns-&-Outs" of the MercedesShop.Com WebSite!
Regards,

Sam... a serious kind of guy

Alright I finally did it!

I didnt have time during the week (work) to really put time into adjusting my fuel elements, but after a good 3 hours today I finally got it pretty well done. Unfortunatley I did not get the two electrical parts you had mentioned to do this job but feel the two elements are within + or - .3 mV compared to the 3 reference glowplugs.

The way i did it was to disconnect all 5 glowplug wires and then I attached loose alligator clips to each glow plug and then clipped the ground to the front strut mount nut on the right side of the engine bay. That way I could quickly measure readings from one glow plug to the next. i made sure to write down the readings after each adjustment just to keep track of patterns.

Took me a while because every adjustment created diffferences in the other readings of the other glowplugs. For instance with every adjustment of the #1 to raise the mV, this would make the mV readings on my #2 go down, but not vice-versa. Yet, raising the mV on the #2 glow plug would make the #3,#4, & #5 (references) go down. Very frustrating! Plus initially I had the nuts holding the fuel element too loose and thus my adjustments were not small enough. As I got closer to my target I tightened the nuts slightly. On top of which I noticed that with every adjustment you had to let the injection settle for a good 15-20 seconds to get a moderatley acurate reading.

I ended up with close to about 10.8-10.9 on each glow plug. After I get the car warmed up tomorrow, im gonna measure it again to make sure they are still relativeley even across the board. If so Ill go ahead and do the IP timing to the engine as well as adjust my valves and insert my new rack dampener pin. Then i will go back and measure the glow plugs again in hopes of seeing raised mV's, so I can guage my efforts.

As of right now, a deffinite improvement in the idling...much less shaking and noise. Havent really put it on the highway yet but I will tomorrow. Just got a new full tank of fuel, so I will report on efficiency as soon as I can.

Thanks so much Barry!

P.S. get some 8mm nuts, I lost a few continously (this was my third effort) removing and replacing them from the GP's.

Jman300sd.
My hat is off to you to even get that close without the use of the resistor and capacitor.
Without them it is very hard to average voltage.
In fact twice as hard as doing the primary pump timing.

It was quite hard without the stabilization as well so can only imagine what you went through.
I would not like to do it without the modification.
I think when you incorporate them into your circuit you will still be able to improve results.
0.3 miilivolts strikes me as still quite a lot if you read that high a difference but as you are aware with the meter hunting it is hard perhaps to do better.

I cannot relate it to degrees but still feel it significant.
Plus since you have done it the hard way the next time with the modification will be like a walk in the park.
Plus more accurate by far I believe.
I myself would not touch the primary pump timing until a few small tests are completed.
That we can discuss later.

What is disturbing me is with the exception of a few we are not getting enough proper feedback yet.
Until we do it will be hard to move this forward.
At present that is understandable.

I also want to be cautious before making some assumptions as well.
Your driveability and fuel mileage might give some indication of how close you are.
Anyways thanks a lot for reporting back.
Plus it is of benefit to other members to report until it is perfect.

Somehow you approached this on faith so to speak.
Remember to only work in your case #1 element to numbers 3,4,& 5 until they are identical.
Only then go to number 2 and work it till identical to 3,4,&5.
Then they all should be identical voltage across the engine.

My thought still is for you to get the capacitor and resistor.
Good going so far as you are the first test horse and are going to completely pull this off I suspect.
Not quite there yet.
But getting close.
Your technique tips are valuable as well.

The finish mv is irrelevant in my opinion it just indicates the heat generated and will vary with idle speed.
Perhaps you mean it will indicate if your tune up is beneficial.
That area is perhaps in the future.
I personally thank you for taking the effort so far though.

.

Barry, you mention i should not touch the primary pump timing. Why exactly is this? You think i should get my readings closer before i attempt this.

Sam, there was an earlier thread where I basically speculated on potential as a valid service tool.
Plus helped or tried to on two people with trouble.
The first gentleman had an obvious well advanced element.
I did not like the ideal of doing it by ear at my suggestion but it worked.
That started me thinking.

The second gentleman did it by ear and voltage comparison but discounted it as he said he thought the result was no better than by ear but that was wrong as he went back and forth till he got identical voltage.
His engine than ran very well.

Although I also fully agree with a hunting meter it would be very hard and hardly seem worth the effort to verify.
He also did not report the hunting meter as well and I was unaware of that effect until I saw it myself and the recent gentleman mentioned it.
Yes all the glow plugs linked or in parallel will provide an engine average.
I personally would like to read them all individually to ascertain that a problem did not exist that would tilt the average excessively prior to linking them all up though.

Say a glow plug was found in the group that was substantially lower or higher than the other four.
That should be investigated as why that cylinder is generating less or more heat.
If it was found say you had one cylinder of low compression and could not rectify it then I would use the other four plugs alone to establish an average.
Could be as easy as a tight valve for example though.
As for the components used with the voltmeter.
No they are not critical at all I believe other than I would want to see the condenser above 2500 microfarad and the resistor at probably 1k or better.

No harm to experiment but I got rock solid last digit readings with my values.
The addition of this is really important.
If you find the peak voltage has a plateau with a little width I would stay at the leading edge of it when you enter it.
That is primarily as we have no indication of how many degrees one tenth of a Milli volt represents yet.
If it turns out to be one or less it will replace all other systems.

As refinements are made we may have to move to a meter that reads 100ths of a Milli volt at some point in the future but at present 10ths of a Milli volt are OK.
I do not have at present and in past a therapist but who can tell the future?
I was speculating about the future perhaps as there is far more to be investigated with this procedure than meets the eye.

We have not even scratched the surface yet and to be hung up a little with so far to go is frustrating of course.
There will have to be a complete guidance manual written at some point as I visualize the uses as possibly extensive.
The last gentleman for instance may have had a really hard time as there is no general guide in existence yet.
Of course to try to expand the applications at this point would only result in bad feedback if not applied properly by a user.
It will have to move pretty slowly so this does not occur.

I do not have the time right now to really do this thing justice or disprove it.
It deserves better.

.

Jman300sd, you have already performed a very difficult task probably well with that hunting meter.

As soon as you get the components to build a voltage stabilizing device it will change everything.
The best pump timing is going to depend on that stability as well.

Your first statement about making sure they are all pretty well exactly the same still carries a lot of weight.
Of course any slight variance on 3,4,and five as individuals will have to be left alone if it exists.

There will have to be a set of protocols worked out at some point.
When you get your meter stabilized I would like to know the reading of voltage on each one of them individually.

At present it is starting to look like you advance your pump to the leading edge of the highest value obtained when reading the voltage.
As I have stated there is no risk if you pin punch mark the pump prior to adjusting as you can always then go back to your mark.

Also am waiting to see who can make or design a pump holder/ adjuster jig to simplify adjustment of the pump with engine running.
Am also starting to concentrate on how much advance is too much.
The last thing I want is pumps over advanced.
This is going to take some thought.

A gentleman set his by piezo electric pulse sensor a full eight degrees over factory setting the other day.
My suspicion is he may be too far advanced.
I am looking for a positive system to indicate that simply.
The old standards of less pre detonation may be flawed.
I now suspect top possible mpg for the type might be the test standard.

If you are too advanced mileage will be less than optimum.
There is a lot of work to do here.
It will take time.

.

I think for now what I have done will suffice in the operation of my car for a while. At some point though I would like to put new injector nozzles and at that point these mV adjustments might be even more relevant. But, I got a long list of things to do before then. I will provide fuel efficiency info as soon as I can.

Jman300d, good ideal as it also provides a chance to reflect on things.
You are right as a term of driving plus indicated mileage etc will give you some indication if all is well.

A little time will add refinements to procedures and that may help as well. Just keep following this thread.
Pretty soon I am going to start doing Mercedes diesel pump to engine timing.
System worked out well so far on Volkswagens. :)

.

OK I'm a late comer, but...
 

OK guys I'm a late comer to this intriguing little project Barry has hooked us on... but what can I do to help this experiment along some?

I do have access to my 1980 model 240D[na], my son’s 1980 300D[na], and my father-n-law’s 1985 300SD [turbo]… and propose that I get my “banana plug” connector test rig put together and initially collect precise readings for each of the glow plugs on these vintage M-B(s).

From that point on I will be need to know what additional steps I might take to help this project along.

I have recently talked my local independent M-B shop owner into investing in a new diesel pulse sensor [piezo technology] accessory that enables him to more readily check the timing on these cars using his timing light… so I guess I could get some data on what the present timing shows up as using this electronic equipment... what do ya think??

The thought just occurred to me that after a car has been peek tuned using this simplified "thermocouple" method... wouldn't it be interesting to have a local diesel injection shop [one with the top-of-the-line "dynamic" bench test equipment]... wouldn't be interesting to see what they might conclude from examining the CAR and/or the IP?

Regards,
Sam Ross

Sam, sounds like an excellent ideal.
Your car with the poorest overall mileage and performance might be selected for the test.

I would set the timing by the piezo method.
Mark the pump and see if it coincides with the highest leading edge of the Milli volt method.
I would not be shocked if it was not a few degrees advanced over the piezo method either with the Milli volt method.

Allowing for aging characteristics or modern fuel perhaps.
This is exactly the kind of information we need.
Can see no reason the two methods cannot be used simultaneously when doing the timing to compare.
As there is no interference between the two systems during application.

.

Barry... see Brian's post at
 

Barry - Thanks for getting back to me so promptly.
See Brian Carlton's post at:
http://www.peachparts.com/shopforum/diesel-discussion/150134-need-help-low-power-80-300d-%5Bna%5D-post1137442.html#poststop
and you will see that the pulse timing light method has to have a fudge factor that luckily Brian has already worked on. He wrote: "With the SD [his 1985 300SD] set perfectly at 15ATDC via the M/B RIV timing, the pulse timer registered 13.5° BTDC. So, I would presume that the n/a 300D [my 1980 300D(na)] should be close to this value."
Which I interpret to mean:
(1) The basic primary timing spec is 24 DegBTDC
(2) which=(s) ~15 DegATDC on the IP using M-B's "RIV" method
(3) which=(s) ~13.5 DegBTDC by timing light equipped with piezo pulse accessory.

Personally I get befuddeled [<-sp?] when I think about the several factors here that have potential to keep these three from being more absolute relative to one another, at least in my muddled brain.

Doesn't:"
(a) age of vehicle [ e.g. stretched timing chain],
(b) condition of glow plugs,
(c) condition of the injector nozzles,
(d) condition of the heat shields protecting the nozzles,
(e) how well the valves are adjusted, and
(f) how well the individual IP "elements" are set-up/timed relative to one another...

doesn't one or more of these [if any] keep us from establishing a precise comparison between the three numbered timing methods above?

If you guys can get my mind straight about these factors and timing methods I think I would be of some help going forward... what affects or changes what aspect of IP timing?

Regards,
Sam

Sam, you have just hit the highlight of the Milli volt timing function on the head.

It does automatically compensate for many factors present as you list them.
All other methods but the ear just basically refer to the factory recommendations from years ago.

Basically #1 injection point in reference to crank marking.
That I expect may be crude in comparison to reading the flame front.
Todays fuels alone are of less quality as well.

It may turn out perhaps on Mercedes that the peak Milli volt reading is perhaps a little too far advanced.
Even if so we will learn to set them a little before the peak.
What gives me hope that the factory recommendations are wrong for a large percentage of cars is the few cars that give substantially better fuel mileage than the majority.

I have suspected that knowledgeable mechanics may have set the pumps a little ahead by experience.
The 240d is a classic example of a possibility as some seem to deliver 15% better mileage than other examples in generally good condition as well.
Plus some of the same owners report much better power than average.
Also we can stand the additional power as well if it is available to us without over stressing the engine.

I am almost certain if the mpg are higher after the adjustment the car is not too far advanced.
If mpg are the same or less than it is probably over advanced.
That is the flaw in setting the pump by ear to some extent.
Too much trial and error.
You might luck into the right spot but chances are you will not.
We will see.

I also would do a fast preliminary check to see that the engine is in pretty good general condition.
Timing adjustments will not mask serious flaws.
But will help compensate for minor ones.
That is okay as these engines are not babies.

A good quick check of your engine is to just read each glow plug voltage separately.
If one has noticeably higher or lower glow plug voltage find out why. Swap the glow plug with it's neighbor first.
If no improvement perhaps swap the injector next.
I assume the valves have been checked at reasonable intervals before this.
Next might be a compression check of that cylinder if fault has not been isolated.
If that is good then you might want to start evaluation of the pump.

I did say evaluation not moving things until you are really sure.
Always remember two glow plugs beside each other that are reading low indicate a possible head gasket problem.
Great verification process of a suspicion.
This method has great potential if we can get past the preliminaries.
Remember it is also the method of choice already for some diesel engine builders to set their pumps to engines during the manufacturing process.

.

Some basic data... mv glow plug readings:
 

1980 240D: [ has 3 relatively new Bosch GPs and 1 Monarch GP ]
1980 300D: [GP's are a Non-Bosch mix ]
mv Readings:
"Composite" readings taken with all GP's connected in parallel !
240D... #1=9.9,..#2=10.3,. #3=9.9,. #4=8.6.................Composite=9.5
300D... #1=10.8, #2=11.6, #3=10.3, #4=7.9, #5=6.6... Composite=9.0
*As I understand it, the absolute accuracy of these mv readings is not really important so my cheap digital meter should suffice.... what's important here will be to eventually dynamically adjust these to peak/balanced mv readings, right?

The 1985 300SD data will have to come later.

Again the 240D and 300D are both geting about the same 22-24 mpg. I expect the 300SD is getting the best highway mileage. Things might improve for the 300D soon by virtue of infusion of a new/rebuilt tranny from Peter Schmid [Redwood City, CA] next week.

The 300D is currently the smoothest/quietest running engine and the 240D is the noisyest and roughest running. If nothing else I hope to get the 240D to settle down by fine-tuning the IP elements and IP-to-Engine timing.

Now I need information on how to proceed from this point. The IP-to-Engine timing I understand and I think my independent M-B shop owner is "on-board" with me on the notion of building a heavy, long-bar, tool that will clamp onto the front of the IP to facilitate this dynamic adjustment. So now I need input and/or will have to educate myself on the fine-tuning of element-to-element timing... something I do not want to jump into helter-skelter!!

Note- I picked up sone "Banana" type plugs at Radio Shack that make it a breez to connect to the GP Relay's connector to take the mv readings... individual one as well and the composite. I can supply further info on this if anyone wants.

I'm still working closely with my local M-B shopowner to try and come up with a workable piezo-electric pulse sensor timing light to quickly, dynamically check the engine/IP timing on the many diesels he sees.

Regards,
Sam Ross