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.

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

Mike

__________________
Diesel Discussion. Where learning is FUN!

1983 300D 296k work in progress
1985 300D (sandwiched) parts
1980 240D engine issue

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.

.

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.

.

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?

__________________
1983 300SD White with Grey interior

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?

__________________
'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg

Mercedes shows a tool, part #617 589 07 21 00 that fastens onto the IP and the block to get the small IP movement required.
Page 07.1-114 shows the device installed and the adjustment method.

__________________
1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom