for VW they built good diesels for the 4, 5 but 6 cyl was a lemon.

they sold the 6 to Volvo, I had a 1980 and didnt lasted very long, i went from a dsl land cruiser to that and 1 yrs later i sold her for a loss. then these dsl mech bought the car for 900 from me which i paid 3500 a yrs ago, they did fixed it & sold her for 3k again. several mths later i saw a lady driving her and she seems to be happy, i didnt bother to tell her the history anyways.

The 1 st went down to 170 2nd was 260 rest were ok. i was told there was a crack between 1 and 2 cyl in the head. that was an expensive lesson though.

some say these vw 6cyl has issues with oil supply to cam shaft.
all in all it was a remon, avoid them. they were no made too many there after.


The Bimmer 2.4 td was a not bad engine, they were sold to lincoln contirentals for few yrs, i was told they have power too. is a 6cyl turbo dsl.

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You Layback, Mr. Smith, WHunter, and GSXR have encountered our favorite troll apparently in a very bored state. His comments and arguments will continue to morph so that his mysterious sources, calls, and credentials confirm and prove everything while pulling in many obscure references to other engines and manufacturers over the last 1/3 century.

You will note that the original argument connecting the chaotic running, bent rods, and failed belt tensioners has never really shown any correlation or data at all, while screaming for data and proof from others, ... and I'm wondering why in close to a half-million miles combined OM603 driving I have not yet had a bent rod nor one of the (fairly rare) timing belt tensioner failures. Would seem that that chaotic running would make for even more timing-chain failures, ... but that is limited to a year or two of OM602s.

He'll be back, with lots of time on his hands, that much can be proven in this thread.

__________________

Gone to the dark side

- Jeff

Thanks for your comments Jeff.
I think you did hit the nail on the head.
Even I dont have the disrespect for some of our very experienced members that he has shown in this thread.
Maybe he could go over to a TDI forum for a while. I have heard that they do a good job of flaming ones like that.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Some seem to enjoy arguing somewhat as a hobby. I guess it's not that much different than playing an RPG on the internet where you are a medieval warrior fighting other players.

I used to moderate on a forum, a thankless job, but there was occasionally someone who just liked to run his fingernails down the chalkboard. Easier to ban them, there are plenty of others with the correct information who don't feel the need to antagonize for their own self-fulfillment.

A shame too as the argument eventually eclipses the information in the thread.

__________________

Gone to the dark side

- Jeff

I hope everyone on this thread has observed how little material there is between the cylinders on the 3.5 diesel block. There is no comparison at all to the enourmous amount present in comparison on the 3 litre block.

It almost appears they expected the head to clamp the cylinders into a stiffer state. Or there may have been real problems if the head did not slide as engineered on the cast iron block.

There is no plausable excuse for this as even visually it has the look of inadaquacy. I have never been able to figure out how this particular engine got released. Almost any reasonable person would say it appears weak..

Yawn.

You apparently assume that more than one of the six cylinders is firing during any given 720 degrees of crank rotation. Possibly you assume as well that it will also be the same single cylinder firing during a given 720 degrees.

Hence the importance of the individual and typical waveform.

No charge for that tutorial. I suspect even the Cat could have figured that out.

Meow.

I enjoy thinking about engines and, intellectually, I do not like it when they fail. I have had the tensioner fail multiple times on my engine as part of my introduction to owning a 300 SDL for only four years and I noted the conditions. It occured to me that the evidence in the rod failures correlated to known harmonic vibration problems with straight six engines as did the tensioner failures.

The mysterious source explained that most (all?) people with access to the data are restricted by non-disclosure agreements.

I have designed and made parts for hundreds of different engines, thousands of variations, spanning dozens of manufacturers and decades.

Last week I took an order for an Alfa V6. Years prior, when Samantha and I pulled the engine from a wrecking yard, I noted the (for me) unusual horizontal use of hydraulic lash adjusters. I then had an interesting (for me) discussion of the valve train on the V6. The customer related that the exhaust rocker failed in competition and was redesigned by Alfa. Sitting here now, I am thinking about the small rocker/follower integrated lash adjusters that I learned of and also investigated in extended patent searches.

Sometimes when I am curious about a subject and I want to do a patent search I am faced with the fact that a cut-off is present in the PTO for searching anything other than titles or categories. I then spend hours opening images of hundreds of patents and visually scanning text and images.

I can hardly be upset because I can remember living in times and locations where patent databases were far removed from me and I could only wonder.

Similarly, when I studied philosophy and someone would ask a question interesting to me I would manually scan the relevant texts. I remembered sitting in the aisle of the stacks for hours scanning thousands of pages of Kierkegaard's work for a particular phrase. Oh, when I studied Kierkegaard it was plain to me that he was a multiple. I talked about this with some Kierkegaard scholars and pointed out the cues. Subsequently one of them published something concerning this, I believe.

In the back of my mind I am working out how quantum computing relates to the theories of formal human reasoning I explored whilst in school. I can see the limitations instantiating themselves as technology progresses. It is hard to explain but thinking about some topics can take over your life and destroy it and I had to stop. I am sure that when I am ready to write about it again that I will be deemed a troll by some.

Well, I got kicked off a Mopar slant six board for analyzing that engine design and having the temerity to suggest that engineering principles and cues from other versions of the engine were relevant. Even (horror) that slant six designs from other manufacturers could offer insight. This despite the designer of the slant six stating that he and his team used elements of existing engines to create it. Sigh. Sorry, don't mean to be a troll.

I even suggested and detailed a procedure for electroforming on the aluminum block versions to strengthen the design. Shame on me.

Anyway, back to rod bending.

Kevin,

Your theory reminds me of 'Pedestrian Excitation' (file below). So far, your hypothesis is the only one that incorporates some 'hidden' force that is inexplicable and bends rods by the mere though of it.

There may be some validity to it, who is to say? Regardless, MB's decision to strenghten the rods does not etirely mean that they came to the conclusion that the rods were at fault. They may have just done so because it was the only fix they could offer in response to this strange, untraceable failure.

Its easy to imagine that some harmonic amplification in a certain RPM range went unaccounted for after all their 'testing'. I don't know if a matched-pairs engine is more susceptible to this type of behavior, but the un-matched 5-cyl was much more...... successful.

Attached Files

PEDESTRIAN_EXCITATION.pdf (170.9 KB, 4630 views)

Thanks, just looked through it. I did not see a mention that troops are often instructed to march in broken step when crossing a bridge for the reasons outlined. It might be discussed in the references.

"I have had the tensioner fail multiple times on my engine as part of my introduction to owning a 300 SDL for only four years"

A simple bit of practical advice.

Number of failures in 4 years

First failure = probably needed replacing.

Second failure =did I do something wrong?

Third failure = better read the FSM or a good DIY

Forth failure = I best say away from under the hood & take the car it an indi.
Have him work out what is causing it.

5th failure = the indi was no good, get a recommendation of a good one.

Do I need to go further?


jt,
That is a good report, most know about the harmonic problem with people on bridges, that report explains the how/why !

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

You assume a lot. Go forth and study some more.

Quote from jt20....."Regardless, MB's decision to strenghten the rods does not etirely mean that they came to the conclusion that the rods were at fault. They may have just done so because it was the only fix they could offer in response to this strange, untraceable failure."

This I find to have a lot of reason. My favorite machinist and I spent many an hour discussing the rod bending phenom back when I had my 91 and we feel it was caused by a failed seal between the head and block which led to seepimg of coolant and or oil into the cylinders eventually causing a partial hydrolock. We also feel it coud be due to build up of carbon from the same phenomina of leaking liquids and burning of the excess.

when we tore down my car the intake was so gummed up that some of the openings you could barely put a pencil in the free opening.

Nobody here really buys it but I still believe it is more plausible than the rods simply bending from being designed too weak.

__________________
[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.

Tom,
The rods were shortened in going from the 3.0 to the 3.5 . This occurred for 2 reasons ; 1/ as the same block configuration was used, the stroking caused the rod bearing journals to be higher up when at the top of the stroke. 2/ the wrist pins were further down the piston for clearance reasons when the crank was at 90deg, that is so the rod was not hitting the skirt of the piston. the fact that the rod is at a larger angle when its part way down significantly adds to the lateral (bending) load on the rod. Its no different to a building column thats not exactly vertical. The load on those rods can be several tons when they are between TDC & 90deg around the max torque of the motor. Probably when the design was done, they just shortened the rods & didnt take into account the added lateral load. Had the stronger rods not fixed it then we would have been looking for other causes.
A hydrolocking type failure would have also occurred after the rods were replaced.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Added side thrust on the upper portion of the piston from the dropped wrist pin location? Piston drag too much for the block material as there are no liners. Quality and hardness of their liner far better than the cast block material the pistons ride against on the 3.5? First mercedes explicity to use no liner as there is not enough meat between the siamesed area between cylinders to enable them.

Does the bend initially occur prior or after the ovaling of the cylinder starts? Blocks too green due to production demands before machining.

Cast iron should be aged for a period before machining. That may be an aditional reason some blocks survived. Simply some where aged a lot more than others before machining. Anyways it does not seem to take very much of whatever it is to upset this engine design. It appears there might be no one specific shortcoming in the design and execution. It could just as easily be a combination of weak design items. Certainly in their engineering department someone should have seen this.

Today there might have errupted a class action as a result. This was not a cheap car. For the money handed over the customer should have gotten a much better engine.