Think he might be a Bimmerfest refugee messing with our MB diesel nerd minds?

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[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.

The earlier thread was based on limited information without the tools being present to pull the precombustion chamber and use a scope to look inside. The scope I'm using has a head that prevents going beyond the precombustion chamber hole. The engine absolutely did not kick off the oil filler cap when running, and there was no white or blue smoke out the tailpipe. On the highway, it was a dense black cloud, clearly due to the fuel not burning and any injector issues. This is why I posted because nothing really made sense here. I won't know the amount of damage until I get the head off, and I'll post all the pics here once I do. I need to see the piston better to make the final determination, and looking at the valves and any debris in the chamber will answer all questions once and for all. With what I've read and heard about so many cars out there with original injectors (and seeing some of the Kent Bergsma and other youtube videos), it would be a surprise that a streaming or intermittent injector could cause all this damage. It is precisely because this failure is so weird, the sharing of ideas and experiences is helpful...I don't have my car to drive, and I'm now facing insanely expensive options to get it back on the road. I absolutely don't want anyone else to go through this.

Dang, that all looks really nasty. Low blow-by or not, how was this engine actually running before it happened? What kind of fuel mileage? Any loping or shaking at idle?

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'82 300CD
"Pearl", the very first turbo diesel 123 coupe
Totaled 11/23/18, rebuild in progress.
'85 300TD, "Artemis".
'78 300D euro, "Ol' Red", mostly retired.
'85 300D, "Gandalf".

There is no way that this engine wasn't shaking at idle with a completely dead cylinder.

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Milan Brown 1979 240D, rebuilt OM617.952 turbo diesel, rebuilt 722.315 transmission (my only daily driver)

Instagram: @maximed93

Yes,the engine ran great. I had just put in a new transmission, sorted out all vacuum issues, and it ran great. Idle was good, but varied. In other words, sometimes it settled down perfectly, other times a slight bounce after a high speed run. Mileage was good. Reason I did not consider it urgent to start pulling chamber and injectors...that work was on the list, just hadn't gotten there yet. So yes, a nasty result. I think it was 'Dieseasel 300' who speculated that the pre-combustion chamber holes got plugged and resulted in the tip being literally blown off. I agree completely, and I'm going to use a University metallurgy lab to confirm and I'll post here the results. As the evolving theory goes, let's assume the glow plugs, pre-combustion chambers, and injectors are all original on the 1982 vehicle. It would not be a surprise that constant cyclic heating and quenching of the glow plug by fuel spraying on it over 37 years, could lead to metal fatigue, and at the least, scale that breaks off the tip. Doing the math, if the car were used daily, and started 4 times a day, every day for 37 years, that would be 54,020 glow plug heating cycles.That's a lot of cycling. So if debris started to accumulate in the precombustion chamber tip, held in place by an accumulation of partially combusted fuel and ash due to injectors that spray less than prime, the possibilitythat the few holes in the tip could be obstructed becomes very real. All it takes is one pressure rise faster than intended, that the peak tensile strength of the chamber is exceeded, and it has only one place to go...back through the injector, glow, plug, or tip of pre-combustion chamber. In this case, it looks like the tip was blown off. Metal flying around in the cylinder would not seem the cause of the tip breaking off, since the tip is not cylindrical but convex, so a glancing impact would likely be deflected.

To clarify, before the failure on the highway, the car idled well with an occasional slight imbalance at idle after a high speed run. When the 'event' occurred, as 'Maximan' posted, there was a shake...a hell of shake in fact...I thought the motor mounts were going to come loose!

I see. I was going to say, if it was loping at idle it could have been a bad injector dumping fuel that eventually eroded the prechamber parts. But the nature of the failure and the lack of warning seem to indicate it couldn't have been foreseen. This kind of failure isn't at all typical, even on seriously neglected cars.

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'82 300CD
"Pearl", the very first turbo diesel 123 coupe
Totaled 11/23/18, rebuild in progress.
'85 300TD, "Artemis".
'78 300D euro, "Ol' Red", mostly retired.
'85 300D, "Gandalf".

I want to know what caused this. My guesses are

a) injectors squirting instead of misting
b) over boost by turbo

Thoughts?

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1976 Mercedes 240D (Sold)
1985 Mercedes 300D Turbo Diesel: 500,000KM
1986 Mercedes 300E (Sold)
1988 Mercedes 300E (Sold)
2002 Mercedes C240 (Sold)
2008 Mercedes C350 4matic

A great site for purchasing industrial rubber products!

Industrial Rubber

How dare you say a diesel needs maintenance. The internet says these are million mile engines.

As for the OP's engine , blame last person that changed the oil. At least what the person in the thread below believes even in the face of facts. See post 43 for pics of an alleged oil change gone bad. Ignore the pics of undamaged connecting rod bearings.

https://www.peachparts.com/shopforum/diesel-discussion/313655-how-could-my-om617-compromised-so-quickly.html

A while back I bought a couple of Deutz 4F1011 / 4M1013 type oil cooled turbo charged engines. One had a hole burned through the piston due to a bad injector. However, these were direct injection engines. As a side note, as an option they have a glow plug that protrudes into the combustion chamber.

I'm still waiting for someone to provide evidence that they can even make it to 1M KM's on the original engine/drivetrain. There's a thread running, and so far nobody's been able to provide a documented example:
How many million mile Mercedes have there been?

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I'm looking at used cars to snag an engine for my 300D....is the OM617 in the 300SD a drop in for my 300D OM617?

There are a few things that are not the same. IIRC you would have to swap the motor mount arms and the oil filter housing, as the 300SD has a electronic oil pressure gauge, and the 300D has a line going to the dash from the oil filter housing to the oil pressure gauge on the dash.

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Milan Brown 1979 240D, rebuilt OM617.952 turbo diesel, rebuilt 722.315 transmission (my only daily driver)

Instagram: @maximed93

Why not repair the engine you already have?

A piston and injector refurb would get it going again.

A step further would be what I call a " junkyard rebuild". Fresh rod and main bearings, if the crank is slightly small that is OK. Resized connecting rods ( both ends ) used pistons, new rings, resurface the head , grind the valves and only replace guides that are excessively worn. Replace the timing chain. Resurface the oil pump cover , housing to get end clearance down. < this is where oil pumps lose volume / pressure when worn.

What you end up is that mythical " good used engine ". The above results in a crank bearings that will have reasonable life and not explode. Good ring seal however , due to worn pistons, the rings won't last 1 million miles. Valves with good sealing but , due to guide wobble , they won't last 1 million miles.

The risks are: A cracked piston due to metal fatigue, a body that won't outlast the engine. This last bit is why I do junk yard rebuilds for a car that isn't going to last forever.

What brand glow plugs are they? Champions, AC Delcos are junk, known to fail with swollen/ dropped tips with use. Streaming poor spray pattern injectors probably did your engine in by squirting 1800 psi fuel onto the hot glow plug tip/ pre-chamber ball and knocked them off. Unlike VW IDI diesels which do not have a pre- chamber like the 617, dropped glow plug tips immediately go into the combustion chamber and wreck the engine.

The 617 prechamber with the small holes should have given you plenty of warning noises from those loose metal bits bouncing around in the pre-chamber before it broke up and wrecked the piston. The failed glow plug should also have given you early warning with poor cold starts.

How many miles have you driven this car before this happened?

You may consider buying my no rust 85 300D which I'll be putting up for sale next week in NYC. 163k original miles, exc running, no smoke, new Monark nozzles, does not burn oil, new rear shocks, no oil leaks, cold AC, perfect interior, everything works, spare set of Bundts, remote key entry plus other non factory features added. I am second owner. PO was old couple in CT who never drove it in snow, they flew down to their second home in Florida every winter and have another car there. I never drove it in the snow in my few years of ownership. I've put very few miles on it since I have other daily drivers.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

What year is your car?

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[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.