It is not a result of the starter motor. If the engine cannot freely spin at consistent rates (after disengagement of the starter and allowing that engines do not normally spin at consistent velocities within a cycle) then the firing regularity will be disrupted and excessive loads put on components.

That's great. Let's hope that when and if your shutoff valve ever starts to fail that you replace it promptly and not allow chaotic firing patterns as the engine struggles.

This is not directed at you, Jim.

I think that manufacturers have an almost impossible task set before them in trying to anticipate in what possible manner their products will be abused from the infinite available set of abusiveness, wittingly or not.

I note that my 300 sdl does not have an automatic system to stop the engine and chastise me if I ingeniously manage to fill the tank with gasoline rather than diesel. Clearly this consumer error can be anticipated and is instantiated.

I convinced my father-in-law to buy a 1981 240D some years ago. Once upon a time he pulled into a gas station and had the attendant fill the car. The kid put gasoline in it. By the time he got home, the vehicle was barely running. He called, I had him siphon the bulk of the bad stuff out (the manual actually allows you to add up to 35% gasoline for cold starts and cold operation) and add 5 gallons of Diesel to the tank, then start it and drive to the nearby Diesel station and fill it.

The car is now being driven by his grand daughter in the Saratoga, NY. Starts like a champ, has another 75,000 miles on it since the gasoline encounter.

While I agree the car manufacturer has a formidable task ahead of him, it is required that to stay in business he take on the task and stay at it. MB has been at it for over 100 years. An automobile engine introduced right around their hundred year anniversary in business showed a singular susceptibility to rod bending. That is in their court any way you slice it.

Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

Why should I waste my time proving or disproving your theory? Pay me for my time and I'll think about it. I'd say that your response is weak but ooops, you already used that one.



Yes, it is not obvious what you are suggesting as a fix. What components would YOU change, instead of the rods, to prevent the issue from re-occuring?


I think it's also relevant to point out that Mercedes did not change the harmonic balancer nor flywheel on the 3.5L engines. With updated rods, the problem went away - period. I'm at a loss to explain why you think only the .97x engines would fire "chaotically" under certain conditions, or how you propose to bring order to the claimed chaos.

__________________
Dave
Boise, ID
Check out my website photos, documents, and movies!

I believe the point being made is, preventing the rods from bending after the warranty period is up is too difficult and one should not expect all the rods to last very much beyond that time period if you live in a cold climate. I would figure one could expect that kind of "learning" event if you bought a Hyundai or Kia. They are new to the business and might get overwhelmed by the daunting task of addressing all the stuff that can go wrong if you let it. Yet I believe Hyundai or Kia would have stood by their customers and accepted their responsibility to provide practical products for the climates they elect to sell into.

Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

One piece of data I haven't seen is whether all rod benders have failed head gaskets. My prime suspect for #1 bending remains hydrolocking. There are big gaps in my theory (by Anne Elk) because it doesn't explain why #1 bends forward only, never backward, nor why #6 also bends. Maybe it has to do with oblique injection directing the bulk of combustion towards the front of the combustion chamber. But that still doesn't address why #1 is a favorite and #6 is the runner up.

In general, I side with the school of thought that says nothing unique happens in a .97. If something chaotic causes .97 rods to bend, the same chaos afflicts other US 60x engines, but they tolerate it. MB simply went a step too far along the path of weight and cost reduction and the rods crossed the line before any other component. Someone suggested that other 60x rods might bend as well. Has anyone checked .96 or 602 rods after significant oil consumption?

Sixto
87 300D

We appear to have been hoodwinked by this discussion about chaotic combustion. I doubt that any of those posting really know what it is & if it is relevant to this compression ignition engine failure. I would respectfully suggest that if it was a problem, we would have seen cracks in pistons & other components that are a surface in the combustion chamber. Maybe pre chamber failures. We dont.
I am concerned that some may have now tried to blame climate. Given that rod failure occurred in both the north & south, coastal & inland, this lacks any merit.
I cant understand why we have a suggestion that some how weak rods are not the problem when strengthening them cured it.
People can speculate all they like concerning the actual mode of failure, however all they are doing is confirming that the rods were not strong enough for the intended application.
With regard to statistical analysis, maybe some need to go read "how to lie with statistics". There doesnt appear to have been any attempt by those who choose to advance arguments with some sort of statistical justification to have undertaken any sort of proper hypothesis testing of there suggestions.
Next we will be hearing the old story about how men have higher IQ's than women & people with long hair are smarter than those with short hair.

It is starting to sound too much like a Sci Fi discussion about some aspect of chaos theory. Maybe some have been taking Dr Who on the TV too seriously.

__________________
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

I am glad the car survived the punishment. Swap in overfilling the sump oil and creating a runaway. That happens too. They even put a warning on the oil cap. I don't see a system to prevent running the engine if there is too much oil.

You see Mercedes creating replacement rods as tacit admission of guilt. I think Mercedes put every version of them through a durability test. I think they all passed. I think it is very difficult to anticipate or model every way a customer can treat a product. I think many car companies would not have made that effort.

So what are you proposing >60% of 350 owners did to blow up their cars?

I am concerned that some who apparently see themselves as a hooded academic sitting in judgment fail to present the data they now cite anecdotally.


I cannot understand why people are not paying more attention to the physics behind a failure that dogs these engines to this day. Pay better heed and address the tensioner failures in the here and now.



Yawn. When you actually present the data you cite then we can determine an appropriate p-value.

Check inside the TARDIS -- maybe it's stashed in there.

The Cat in Red Dwarf ate it.

Are you saying that >60% of 350 SDL engines had bent rod failures?

Yes. This was not an occasional failure.

Source of your data?

Edit: congrats on 2000 posts.

Edit 2: maybe you guys think I am being soft on Mercedes. I caught hell when I suggested that Porsche started stamping serial numbers on the big and small ends of the sinter forged rods in the 928 because of some screw up.

Data, data, they wanted data. I found pics of rods without serial numbers. I found that both numbers and model specific info was subsequently added to the rods (some versions of 944 and 928 rods are nearly identical). I found pics of the factory floor where rods were stored loose in bins.

Finally a customer of mine had a failed rod bearing. He sent me high-res pics of the build about two years prior. Of course I had saved them. By chance he took a snap shot of the rod in question with its MATCHING serial numbers.

I pointed out that the morphology of the GKN sintered rods was used to index them and this rod pair was obviously mismatched. Still disbelief. No matter, I contacted the general manager of GKN. He could not say much but he did direct me to a company selling bits from the F1 TAG V6. Wonders of wonders the cap and beam of a F1 part were mismatched. Even having serial numbers did not fully prevent the problem.

Q.E.D.

We just disagree. Toyota's Lexus division would never have left its customers holding the bag like this. Neither, in my opinion would Kia or Hyundai.

The issue at hand is rods bending in a Diesel engine designed and produced by Mercedes-Benz, sold by Mercedes-Benz in two separate automobiles series designed a produced by Mercedes-Benz in Europe, for sale in the United States and Canada that I know of, that exhibited this rod bending characteristic that not duplicated in any other Mercedes-Benz for sale to the general public. There was never any suggestion of abuse, and I asked as I was stunned that the engine had internal damage. Your responses are becoming less specific and more general about abuse of kinds that even range to mis-assembling internal engine parts by customers and have no bearing on MB 350SD engine rod bending. Most S Class car buyers don't even change their own oil, much less meddle with internal engine parts so examples of complex errors don't make the case for abuse of these engines resulting in bent rods any more plausible, to me.

If chaotic ignition events in cold weather were really to blame, why do other machines designed before and after the "rod bender" Diesel engine not suffer the same fate? No number of other horror stories of other kinds of abuse to engines makes your theory of chaotic ignition events as customer abuse any more plausible as an excuse for MB to hide behind. This is the manufacturer's problem - it is apparent they know how not to have rods bend in equal or more powerful Diesel engines sold in the same climates as the 350SD series. To pass this off as customer abuse is absurd. The car should have come with a sticker on it that said it was not suitable for normal MB Diesel engine car customers, especially in cold climates.

Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)