Weak Component in 240D

[Addicted]

So I have to ask this question. I bought a 240D way back (my first project) and everywhere I looked there was 240D's with Rod Knock. As to when it came to looking for a crank it was even harder to find. Again finding many many engines that were good but with cranks that had been turned once or multiple times. (as mine had been done a full 1.00mm over) As for 300Ds, have yet to find one with rod knock.

After months of looking I finally found a crankshaft that was standard (I already had the bearings and didn't want a turned one).

Anyway was rebuilding it last week and after getting them all on realized (my crankshaft NOT standard). It had been turned once over.

It was thought to be a standard crankshaft and I never checked it as I just assumed it was as I was told it was.

So I have a couple hypothesises

#1: Something seriously wrong with the metal/alloy they used in making the crankshafts for the 240D. Made millions of them and just didn't know until later down the road.

#2: The type of people who chose the 240D are nimrods and chose to run their oil forever/or completely out.

#3: Is it possible for the 240D firing pattern to put out more pressure on the journals. I know that they should have about the same compression rating as the 300D and shouldn't make a difference but just a thought.

#4: I've also noticed that the #1 and esp the #2 take the beating most of the time. This is what leads me to beleive it is more of an operator error problem in the 240's then then anything else (possibly to do with the location of the sump thus pulling dirty oil in that direction past those journals)


So am I just dreaming this up or is there something wrong here?

I don't know about rod knock (since I never got it to start) but my 240D had a little more than 250psi compression across the board with only 196k miles.

[Gurkha]

OM616 and 617 are bullet proof,bottom end more so,have seen them last up to 500,000 with just top end job,the engines IMHO have no weakness except for horse power issue.

[Ara T.]

I'd think there are less turbocharged 5 cylinder engines with bad cranks or rods out there 'cause they're built stronger to withstand the increased pressure from the turbo.

[MBeige]

And considering today's increasingly fast-paced lifestyles and driving habits, these 240D's are pushed to its limits more than they were 20 years ago. Combine that with the above post and you'll see more wear on these cranks/engine parts.

In addition when people bring them to mechanics, these indies tell them the cars will run forever and so the owners won't maintain them as much (owner/driver error) because they're said to last so long.

Frankly I'm surprised that you're complaining of seeing these cranks worn on those cars. I would think another car's crankshaft would par much less than this one. The engine may have been dead on those cars before these 240D's ever needed a new timing chain.

[P.E.Haiges]

Addicted,

The turbo engines have the crankshaft journals nitrided to make them withstand the extra force the turbo provides and makes the journals less prone to wear.

P E H

[Addicted]

Great input and I'm not complaining. Just something I noticed and thought it would be interesting to find the culprit if there was one. I mean crap. This car I have has 300K on it. But then again nobody took care of this car according to the records after the late 80's. But my wagon on the other hand 290K never rebuilt, and maintained well, runs like it is brandnew. So I agree they are bullet proof but not nimrod proof . And it just seemed there are way more 240d's with the problem.