I know some universities had microfiche printing machines. GVSU did when I was there in 2004. I'm looking for a machine I can use for cheap / free. I bet one exists.

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I am not going to make copies at my own expense but you now have a bibliography....I also suggest the W126 FSM CDs but, again, I don't know if it's there, I don't have a W126 FSM.

Calling it theory is your choice - but call it the FACTORY'S theory, not mine. I do not claim it as my idea. All I'm saying is the .96 turns faster (max 5150 RPM) than the .97. Even the OM606 was lowered, for whatever reason (max 4,800.) With other conditions being similar or the same, lateral rod load increases with longer stroke, sometimes exponentially. This applies to any reciprocating engine, not just Mercedes. I also do not claim it was the one single successful solution. Again, based on the evidence of more than one change, the factory was looking for multiple causes.
Exactly, and the FIRST revision was before the .970 ended. Actually, I think the EPC lists the first redesigned gaskets are N/A now.

I found one shop that can still process them. They know what they have - besides a captive audience.


I'm not an X-ray tech but I am a volunteer EMT. I do know most places now use a detector and not true silver containing film. The detectors feed directly to a computer and are MUCH cheaper per 'picture.'

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

FWIW I've seen multiple different max rpm settings in the service documentation.

See this thread: Need some 603.970 service info

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

That is the correct RPM compu, I remember that thread well.

Some of the confusion comes with the difference between full rated RPM, the RPM at which full power is available, and max. no-load RPM, the max. it will rev to without a load.

With a mechanical governor as these pumps have, you have a throttling zone (discussed in referenced thread) where the governor starts to limit max fuel flow, the engine can rev higher with the fuel limited if the load is decreased, but can't develop max. power.

Anyway, again I have to state what might is still being missed, the 603.97 engines were running at a reduced rpm from launch. If there were some "lesson learned" from the rod bending, it would have happened before the rod-benders were even launched! If this were so, then they would have discovered the problem before launch, tested engines to destruct with the new RPM limits and verified that the problem was solved by the change. Further, this was in the '80s, where we were using plenty of P-method dynamic FEA/FEM, not the '50s where one had to guess and test, the failure if a simple product of the forces multiplying at higher RPM would have been excruciatingly easy to duplicate and model in the FEA software, we had a computer system dedicated to this function as well as a vibration lab, and I personally was on-board with several instrumented tests involving the OM603 powered 124, ... it's not like they used dartboards for decisions in this engine.

It is as likely IMO, that there was a harmonic in the engine's operation that matched the natural frequency of the rod, and caused it to fatigue during idling, which forced the change of idle RPM in these engines from the original 630rpm to 610rpm.

So, if the RPM was the problem, and no 603.970 engines ever were delivered with the higher RPM limit, how did this affect the engines?

As far as the 126 service manual, there is no engine service manual for the 126, engine manuals go by engine family and there is only one 603 service manual (plus revisions as it changed), regardless of which car it went in. The manual covers all 601, 602, and 603 engines including the 603.971.

__________________

Gone to the dark side

- Jeff

I have seen that happen in a oval track car. The thing would run all day at 9250 rpm, but bump it up to 9700 rpm it only took 30sec and bang. If we went from 9250 to 10,000 rpm very quickly, it would run at 10,000 all day long.

So it bent a rod?

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

SERIOUSLY??



I'm sorry, because I enjoy and respect your postings, but this just isn't scientific, nor is it in any way documentation of anything, ... nor a bibliography, it is heresay for the most part.

Without any documented data, there is no evidence whatsoever of your claimed failure cause and effect. Not to pick, I'm happy to discuss theory, but it must be stated as theory and opinions, not as a conclusion derived from existing data.

I would love to be proven wrong with the existance of data, but again the data must be verbatim, as it otherwise is open to interpretation.

__________________

Gone to the dark side

- Jeff

Well I'm tracking down a scanner....

You started to pick a while ago...I posted exact document numbers and date of publication from the factory. Were you able to find or read them?

I DID NOT PROPOSE, THEORIZE, EXTRAPOLATE, etc. exactly WHAT THE CAUSE WAS, by itself. I pointed out what the factory did to remedy the faults. Problem 'A' presents itself - Solution 'B' is implemented - Problem is no longer present - Remedy(s) have corrected the fault(s). Call that theory from a crystal ball if you like but it's still concrete, irrefutable proof the factory found an effective remedy for the problem. If you check with the dealer, and I suspect the EPC, the info on the rods isn't showing a change. The factory's data is there 'verbatim' but I will not spend more money than I have by reproducing it (possibly violating copyrights) or read it to you. I clearly posted where I found it take it or leave it - but don't refuse it until you read it. BTW, there is now a wiki (not leaks) entry about the 3.5L rod benders detailing what the factory and dealers did. A 'scientific rebuttal' without supporting evidence isn't a rebuttal. Now, your theory is harmonic vibration - it's YOUR turn to post supporting evidence, otherwise it's safe to say harmonics is nothing more than reading tea leaves.


Excerpt cut and paste directly from the wiki page:

In 1990 the 350SD/SDL debuted, using a larger-displacement 3496cc OM603 engine that had more torque and a lower top RPM. The engine lived on in the w140 chassis after the w126 production ended, as the 300SD or S350, with a larger yet turbocharger and thus more power and torque. By the time of the 3.5L engine, the cylinder head issues of early 3.0L engine (US 1986-1987) had been corrected. However in the 3.5L there exists a different situation that appeared on some engines; eventual head gasket erosion, and thus passage of oil into the #1 cylinder. As the 3.0L engine uses the same head oil passage design, yet does not appear to exhibit the problem - it might be that the larger bore in the 3.5 engine, the higher pressures, and resulting smaller head gasket surface area could conspire to cause a gasket erosion issue. Elevated oil consumption is an early warning of imminent problems. If enough oil finds its way into the cylinder, at some point a hydraulic lock could result in a bent connecting rod, and possible complete engine failure. Some anecdotal sources suggest that the connecting rods are weak, but it's not so much weak rods as the non-compressibility of a liquid. With a bent rod comes ovaling of the bore as the 3.5L block does not have sufficient bore material to allow for sleeving. If one catches the problem before it has progressed too far (after elevated oil consumption starts, but before the bent rod occurs) the issue can be alleviated with a head gasket replacement. Generally these problems seemed to appear more in engines before they reached 75,000 miles of service then they did in engines after 75,000 miles of service.

It should also be noted that not all 1990/91 350SD/SDL and W140 chassis cars with the OM603 3.5 liter engines have suffered head gasket and/or connecting rod problems. In fact there are many documented cases of these engines accumulating well in excess of 400,000 miles without these problems. There is no conclusive proof and a lot of speculation as to what caused the problems discussed above. There is no definitive record of how many OM603 engines have actually failed. Negative results always tend to be more widely reported than positive results. Many owners of these cars are enjoying them without the problems noted above or below.

A secondary problem with either the 3.5L (though true for any of the OM60x family diesels) is lack of maintenance of the motor mounts, which results in hard engine vibration from the engine resting on the frame members. Especially in the OM603, the vibration helps loosen one of the myriad of small screws in the crankcase which primarily hold on the windage tray. If these small bolts / screws find their way into the oil pump or passages, the resulting oil starvation can cause bearing failure, and subsequent broken / thrown rods - usually cracking the block. Proper maintenance eliminates these issues.

The result of both these issues was that some 603.97x engined cars had engine problems. While never formally recalled, Daimler-Benz replaced some engines under warranty, even somewhat after the original warranty term expired (at least for the original owner).

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

Take a chill pill guys I want to see some good data put forth in this thread, not have it locked.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

True, I read your PM. I think you have some other things going on besides the RPM governor. I saw the 0-60 times posted somewhere yesterday or the day before. Did you measure your times? What all have you checked out as of now, and what were the results?

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

I like the Wiki page. It clearly states the theory that my favorite machinist and I came up with on our own.

I could never get my head around the idea that the rods were failing in a structurally compressive manner because of any combustion event in the cylinder which could have been forseen by the typically thorough MB Engineers.

As a head gasket fails first there is often a seeping into the cylinder. While the engine is running this will be blown out through the exhaust, but when you shut it off it will seep until all residual pressure is bled off. This could be coolant or oil. the combustion chamber in a diesel is about 1.5 teaspoons volumn so it does not take much to occupy a lot of the combustion chamber. It is possible that it would not even have to be full to bend a rod but if it occupied half the volumn it would raise the compression to a value which would possibly exceed the design strength for the rod.

If this happens the rod will bend. It might actually only bend it very slightly but when they bend they twist so the piston is now being rocked in the bore instead of coming up and down as designed. This will soon wallow out the bore and cause oil consumption.

I looked at several 350SDL before buying mine. Each had a small miss at idle so I passed. I now suspect they had bent rods undiagnosed.

Unfortunately I knew nothing about the rod bending syndrome until i was the proud owner.

It was that car which attracted me to this forum. as you can see I have really enjoyed my time here.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

They broke mid beam. The ones that weren’t in two pieces showed witness marks on the sides of the beams where they contacted the counter weight. The thinking was that the beams started bowing back and forth until they failed. The cylinder ware marks were consistent with the piston cocking back and forth.

In that type of application everything is on edge, so it doesn’t take much to upset the system.

"What happened?

Catastrophic engine failure.

What causes that?

A catastrophe."

Again you have ducked the issues. You have posted a Wikki, which is a user-submitted info site, no data nor documentation. You have referenced documents that don't exist, or at least nobody can find them, and have all but dropped your original blame on the RPM, which didn't even exist on the .970!

Have you at least then retracted your theory that max. operating RPM was a factor in the rod bending?

__________________

Gone to the dark side

- Jeff

Photos of bent rods here: http://www.w124performance.com/images/OM603_misc/603.971_bent_rods/
Thanks to Dave / GSXR.

__________________

Gone to the dark side

- Jeff