Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help

Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

LinkBack Thread Tools Display Modes
Old 05-23-2006, 02:18 AM
Registered User
Join Date: Oct 2004
Location: Germany
Posts: 348
Originally Posted by barry123400
Also for everyones thought I have an ideal that we can make a comparator with four,five and even six piezo connectors so we will eventually just clip them all to all of the injection lines and will be able to read out the exact spacing in degrees of each element while engine is running.
Barry and others:

So you think it's individual timing and not amount of fuel?
I will ask an electronic to use an oscilloscope with 5 piezo inputs but just to verify how accurate the mV-method is. Further he is overthinking an assembly of 5 (analog=slow) mV-displays probably with signal amplifier to deal with all values at the same time for better adjusting the elements.

Reply With Quote
Old 05-23-2006, 02:41 AM
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
Welcome back Barry, honest I was only borrowing YOUR THREAD...

for a while. Your idea of using piezo-electric pulse technology to concurrently monitor all of the elements of these mechanical Bosch IPs in our vintage M-B is brilliant... but as I see it, a next best step forward is for us to get more people who read this THREAD to at least progress to where they fine-tune their IP-to-Engine timing using this mv technique.

If only we [ me and my M-B mechanic friend ] can get a piezo-electric timing light accessory to work reliably for us, then this would let us more easily check what the existing timing is. We don't have a
M-B "R.I.V" instrument. The Ferret brand sensor accessory has not worked out for us, so we are now looking at a Snap-On model that I think sells for ~$350.00. We will hopefully learn something from our local Snap-On route man who makes his regular call on us tomorrow. The electronic [inductance] timing light we are using is one of the latest that Snap-On has so hopefully that will count for something in trying to get two instruments to work together!

Welcome back Barry!

Yellit - will get back to your post tomorrow!

Reply With Quote
Old 05-23-2006, 03:43 AM
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
let me throw this one at ya... before turning in here on the LEFT coast!

Here is a sketch depicting something I think our timing tool should have...
a protective layer of neoprene to protect the surfaces and s/n plate of
the IP.


Last edited by Samuel M. Ross; 07-11-2006 at 02:24 PM.
Reply With Quote
Old 05-23-2006, 05:56 AM
Registered User
Join Date: May 2004
Location: Flowood Mississippi
Posts: 438
IP tool

Tried the O-scope today to read the 6.9-7.0 millivolts that my 4 digital voltmeters were reading ....4 different brands of digital meters...a cheapie,Beckman,HP,and on each glow plug... $10.00 cheapie read as accurate as the $300.00 HP...glow plugs are new so all readings were close without parallel averaging hookup...The O-scope only went down to a 5 millivolt per vertical division resolition so I could not see the small changes in the dc trace....The meters were more easily read.....I noticed that after the +12 from the relay to the glowplugs shut off which was as soon as the engine started...the glow plug voltages are tracked down from about 15 millivolts to the stable 6.9 millivolts over a period of about 10-15 seconds...this would be the cool down from the glow cycle maybe ......I think the glow plugs are tied together in the relay so external jumpers may not be needed if you leave the relay plugged...I read them both ways...not much difference...did not try to adjust IP yet...still making tool similar to Sams design....kevin
Reply With Quote
Old 05-23-2006, 08:37 AM
Registered User
Join Date: Sep 2004
Location: Canada
Posts: 495
Question- Basics of Diesel Timing

I want to ask a real simple question- does a Diesel engine's timing remain constant in terms of degrees throughout its RPM range, or does it change as RPM's increase and decrease?

I know that on a gas engine, the distributor timing angle advances with RPM as the timing plate is altered by centrifugal force and vacuum assist. Does the same principle hold true for Diesels?
Reply With Quote
Old 05-23-2006, 08:46 AM
Registered User
Join Date: Sep 2004
Location: Canada
Posts: 495
Another Question- VW vs. Benz

With the early (pre-TDI) VW Diesels, the pull knob on the dash had two functions- increase the idle speed for cold idling, and it also advanced the injection timing to assist starting. However, the MB "turn-key" knob on the dash only serves to increase the idle. I wonder why MB didn't include the timing advance also?

The VW system was kind of neat. As instructed in the owner's manual, it should be pulled out all the way for maximum advance when cranking a cold engine, but ONLY if the temperature was above -10C. If it was colder than that, you're instructed to leave the knob all the way in, until the engine started to chug- then you would pull it out, and with the sudden advance, it would usually start right up.

Barry- with the work you've done on VW's so far, have you investigated the effect of the timing advance pull knob on your milli-volt readings?

Reply With Quote
Old 05-23-2006, 09:01 AM
Registered User
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
Thanks for indications that everyone is thinking.

Sam if you say where low on amount of fuel coming from an individual element then when you adjusted your sequential timing you would just not reach the same value.

Just too much less heat available.
You would instead reach a lower peak.
Actually that is a standard volumetric test in itself.
Just collecting injector output into a calibrated container over a specified time.
Recommended pump test if suspicious of this problem at dealer level on rabbit/Jetta diesels years ago.

All we have to do is look up information to access this.
In fact will dig up my Bentley Volkswagen manual later today and post the information if it's there.
My feeling probably wrong is that this problem may not be all that common originating in the pump but possibly far more common with a really dirty injector.

Again I might be wrong.
Above are just again just my opinions and anyone should challenge them if indicated.
You cannot hurt my feelings as the women over the years have made me almost immune.
Come to think of it us guys pale in comparison to their abilities in that area.

Also we can add an amplifier on to the piezo crystal output of the first injector and use it to fire a normal timing light or one we design as just an add on.

But this again is just too early to really pay any attention to.
Yes I think concentration should be given to the pump timing aspect first overall and to stay focused as you suggest Sam.

The gentleman who used the scope indication is a real asset to this going forward as well.
I hope the piezo output devices have no ringing effect and probably not as others would not have them for sensors.
Or that the injector opening is nice and clean vibration wise.
It probably is.

Anyone is welcome to dig in and post from my perspective as I still see it all for the common good eventually I hope.
I think it is starting to really happen anyways.
We should break this into two separate areas and threads pretty soon as the only operation manual initially might be some of us printing off the individual threads for reference.
Just my opinion.

Sam, I also do not consider it my thread.
Instead just a venue to see if this can hopefully amount to anything really with everyone involved.
I realized I did not have the time to give this my best if limited shot quite awhile ago as just too many alligators right now.
With their population increasing unfortunately.

I would like nothing better than to go out in the garage and work this out or attempt to on at least one aspect of it.
Also yes there has to be an advance curve built into the pump.


Last edited by whunter; 03-19-2013 at 02:21 AM. Reason: spelling and readability
Reply With Quote
Old 05-23-2006, 09:24 AM
Registered User
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
Coldwar, the answer to if I have dealt with the cold pre-start manual timing advance on Volkswagen is yes from a consideration point of view.

I first tried to utilize it as an indication the car was too far advanced.
It kind of, but again only an impression indicated on my own car that I was at the top position of usability when pulled out.
More pronounced effect it appeared but also since could not get car into obvious pre-ignition cold or warm with it out thought it was just a good indication in general.

That is compounded by the car starting easier in general to get a truer clear picture.
Still trying to get an accurate mileage reading as well but is harder than I visualized.
I just know it is higher than before the pump re-timing so far.
Plus of course the engine is not in perfect condition as compression is a little down and uneven perhaps, Injectors have never been checked either to my knowledge and overall mileage is getting up there.

I also have no data from the other two done other than the more apparent power form time of initial adjustment.
At least no apparent problems so far.
Or my phone would be ringing.
The only thing faster than bad news is lightning I suspect.

As for why Mercedes did not make some provision to increase timing to make cold starts easier and at a lower temperature?
Anyone that has owned both brands of cars has thought about it I think.
It just beats me and would have made a world of difference I believe.

Also forgot to include there has to be a mechanical advance curve engineered into the pump.
It does not appear to be linear either as some owners of Mercedes diesel engines with timing too far ahead have reported with quiet idle ( or should I say normal) engine runs poorly at elevated rpms.


Last edited by whunter; 03-19-2013 at 02:24 AM. Reason: spelling and readability
Reply With Quote
Old 05-23-2006, 10:30 AM
Registered User
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
Someone posted just hooking up four meters and tuning the elements.
This is not a good ideal.

First you have to prove they are out before anything and all you might accomplish at best is questionable.
But at least the idea has been mentioned.
I am not shooting it down either just stating to try to wait until a little more progress has been made.

There are far too many reasons why one glow plug will read differently than another.
Perhaps that might be good for peaking each element but we have no indication yet of actual accuracy of the Milli volt approach.

At a absolute minimum you would have to have all your injectors pop testing at same pressure plus spray pattern checked or an old engine you were just trying to get the last miles from perhaps as it might just compensate for general wear and parts out of normal tolerance.

Try to wait for the emergence of the piezo device.
Then it does not matter about any underlying problems.
You should get accuracy based on the items design.

It truly will be a good item to just do a general check with alone.
And if made available through a loaner program will accumulate millions of miles in postage over the years.
In fact if the post office funded it's development they would make a fortune.

It will have to be user friendly and rugged and accurate.
Plus needless to say reasonably cheap to build.
There is some design work ahead on the collection, processing and readout of that assembly.
May even require a master clock running in the electronic design.
Should readout in actual degrees difference in each element in relation to the others.
Not that complex to design but does require electronic types.

Again you might be courting disaster to try the multi meter approach.
We have no information about sensitivity of reading related to degrees at all for starters that I am aware of.
The only approach presently even thinkable is basically if you know you have one element off through tampering you should be able to approach it's original position to restore what existed before but again with unknown accuracy.

Or you have established pretty good proof a pump element is off through wear and tear for example.
Just better than being way out perhaps.

A gentleman is trying a comparison of two methods to establish some semblance of equality if any between the two.
This is very important.
Now timing the engine to the pump is a much easier and a lot lower on the learning curve.

In my opinion there is no downside as long as the pump is marked before adjustment.
We will learn really fast if it is the pumps peak voltage setting that is really desirable plus if not what is and will set pump by that method.

Also will give some indication of the plateaus dimension at peak voltage.
That is probably okay as other manufactures use this method.

Now where it shines is for the gentleman who reported his voltages all over the place is to find out why they are.
It even helps verify that you have found it.
Our previous method was basically to spend money and guess.
I really want to remove getting an old diesel being like marriage.
Sometimes cheap to get into but can really cost you over the long haul.
Others I hope feel the same.

I am just an amateur and what is developed here should be usable by all without fear or you landing up worst than your beginning.
Actually my original thoughts.
Well better get off the soapbox and get something done today.
Keep it coming.


Last edited by whunter; 03-19-2013 at 02:31 AM. Reason: spelling and readability
Reply With Quote
Old 05-23-2006, 12:26 PM
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
I have a " high-res " photo of the space around the IP...

that really brings home the reality of just how cramped it is around the front-end of the IP. It's going to be a real challenge to come up with a design that's easy to fabricate and assemble onto the IP. I like the notion that the tool be useable in stages... e.g. use the clamp/lever bar without the hold-fast feature connected to the engine. Why you ask... well once a piezo-electric accessory is found that will reliably work to drive a timing light for these vintage cars, I can see a shop with 2 mechanics working together to first quickly check and then if needed quickly set up to adjust the timing without ever using the hold-fast. Once all but one one of the three hold-down bolts on the front of the IP are loosened, you should be able to adjust as necessary, tighten one bolt to hold that new adjustment, shut down the engine, tighten all bolts on the IP, and then close the hood... all of this as a final part of a general maintenance check on these vintage diesels!

Once we have such tools as a reliable piezo-electric timing light, and our developing IP timing clamp/lever, all we need then is a more complete understanding of the mv readings off of the glow plugs and how best to fine-tune the IP-to-Engine timing accordingly.

Yes, I see great potential for using piezo-electric technology to further refine and fine-tune our aging diesels, but I think right now this is a bit "cart-before-the-horse". Let's get the more practical application on line first. I must defer to the expertise of those like Kevin [aka " yellit " ] and others to think through and/or tinker with the notion of hooking up multiple piezo sensors to check the inter-relationship of timing between the IP's elements. On that note, I guess for a 4-banger like our 240Ds, that relationship can be calculated by dividing 360 by 4... so it would be 90 Deg. of CAM and IP rotation and double that for crank rotation (180 Deg)... and for the 5-cyl engine it would be 72 & 144 Deg. and so on. Is my thinking correct guys or is dementia setting in?|

Reply With Quote
Old 05-23-2006, 02:11 PM
Registered User
Join Date: May 2004
Location: Flowood Mississippi
Posts: 438
IP Tool

Hello all...
My hooking up the 4 DVMs to the glow plugs on my 240D was not to adjust individual elements as I do not think these should be adjustable on the Bosch pump without putting on a test bench....

Lucky I have an IP shop friend that is following this thread and he says leave element settings the stuff is very touchy...

The meters on each glow plug were just to see how all the millivolt readings tracked each other when I had the averaging parallel hookup disabled....

The O-scope could see the -6.9 dc millivolt-age average but the trace was like a fuzzy caterpillar...

what was interesting was a square wave riding on the trace about every minute or so...
I think this may be the Alternator output ....
I will check that again because it was too clean to be spurious pickup....
And I cannot remember if I had the relay plugged in.....

I think a vacuum tube voltmeter would be best to use as a peak indicator for its small voltage reading ability and needle sweep to set the peaks...
Also a very low loading effect on the circuit under test...
I need to get one to test with.....
As for the tool...I have brought my spare injector pump to the office today to measure and fit some of my scrap steel following Sams drawings...

I am thinking of putting extra supports around or in the heads of the 2 head bolts to provide support for the threaded rod assembly that will attach to the rocker cover, they can just rest on or in the head bolts, as the force will be applied in a sideways direction....

This forum stuff is the most fun I have had since I was a little kid..

So happy to meet folks with similar interest...
I just cannot seem to get my girlfriend interested in Diesel injection pump millivolt measuring theory conversation......
My tiny feeble brain is starting to liquefy from all this thinking!...


Last edited by whunter; 03-19-2013 at 02:36 AM. Reason: spelling and readability
Reply With Quote
Old 05-23-2006, 02:27 PM
Registered User
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
No dementia there Sam.

The possible future existence of the multiple piezo device could not be totally left behind.
Just makes things much easier and more accurate or sure for those interested in the sequential timing.

Also did not want people hung up on only the Milli volt application for sequential timing as there is so much work before you are ready and sure to apply it if workable.

But possibly still the best approach for general trouble shooting.
The piezo device on the other hand is totally isolated from everything I believe other than opening pressure of the injectors.
Application skill levels will vary.
It's gotta be nearly foolproof.
If not the working mechanics will hate us.

Believe it or not just trying to make it all easier in the long haul.

Failures will hurt and set back progress.

I believe we should divide threads a little later this week so everyone will realize that we are dealing on two items.

Of course we will as a group keep working on the engine to pump timing.

That builds faith in the future and might even get me off the nut list.
I believe someone is popping over with his pump holder this week.
I looked under the hood on one of my 240s and felt there were better minds out there for this than mine.

I am a slow learner but instinctively knew enough not to open the hood on one of the five cylinder cars.
Only contribution I might make is the ideal of squeezing the pump in a clamp must be moderate towards the front I believe unless someone can post knowledge of the internal construction.

Or load is perhaps carried towards either the upper or lower flanges.
Or measure the deflection if any under clamp pressure.
May be none present.

Also for a project perhaps one of the younger members could interest professors in having a go at writing software to deal with the incoming pulses and produce a rational screen output.

Remember master resettable clock in sync with one of the pulses allowing display of the degrees to the other elements.
It is likely to be a time equation conversion.
Then we just ship the wire harness around from a loan program.
We get the software and we are in business.

I have no doubt that you are on your way Sam.
Your constant ideas are very refreshing.
Your grasp is getting better and better as well.

Anyone can private mail me with better approaches to the multiple piezo problem or post their views when the new thread is launched.
What I do not know I will try to find out.
I will only comment on things to do with pump to engine timing until that time.
Only fair.
We want to get that working out first.
That means I better get that hood open again and have a look at all the present bracket ideas I guess.

Cannot avoid it as it will soon be show time.


Last edited by whunter; 03-19-2013 at 02:40 AM. Reason: spelling and readability
Reply With Quote
Old 05-23-2006, 03:00 PM
Registered User
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
Yellit my appologys. Good work and thoughts. Glad you did not want to disturb elements. My misteak. I make lots of them unfortunatly
Reply With Quote
Old 05-23-2006, 09:52 PM
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
A 2005 post... somewhat a sidebar but still related to Barry's THREAD...

Today while housekeeping my computer I ran upon this 2005 post I had saved:

and wanted to make sure those reading this THREAD have an opportunity to read this. It talks about how cam time is adjustible using a "Woodruff Key" and what the latest author "Doktor Bert" recommends as far as varying timing from the official MBZ specs!

Reply With Quote
Old 05-26-2006, 02:37 AM
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
this is to report that Yellit is working feavorishly...

on his IP timing lever/tool and I have been following along kibitzing from CyberSpace! Here is my latest stick sketch idea that he is considering!
We will show you pictures when he is far enough along that you can recognize what it is.
P.S. - I grew up right near where he lives there in central Mississippi !

Last edited by Samuel M. Ross; 07-11-2006 at 02:27 PM.
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 09:54 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page