OM61x crankshaft questions
 

I got into a bit of a debate with a Youtuber on the reliability of MB in general and it eventually turned into this guy taking a dump on the OM61x family of engines for reliability. Long story short, he basically said these cast iron diesels were "notorious" for breaking crankshafts. I've personally never, ever, heard of this, but I'm looking to fellow owners who I'm certain know what they're talking about to either substantiate or quell what he said.

1. ARE these engines prone to breaking crankshafts?

2. If so, why?

he must be confused

I cannot imagine any scenario in which any mercedes would break a crank. Now if a person of little skill tries to replace the harmonic balancer the nose is easy to ruin.

Never heard of crankshafts going...

...but chilled cast iron CAMshafts are a different story.

But that's more of a vacuum pump blowing up and jamming the timing chain and then the camshaft gets broken.

Alternatively majorette mechanics who like twirling camshafts prior to assembly might have had the odd mishap when they dropped them.

Small print => please note not all OM61X camshafts are chilled iron check your FSM for details!

we used that method of freezing bearing races after heat treat.Made the metal more stable at different temps.
There was a french diesel sold in the US that broke crankshafts like crazy Peugot can't spell it right.

This is what the guy said:

"Peugeot Indenor engines are way more robust.Ever seen bad Benz casting and forgings?I have. 240D and 300D Turbo Diesels used to break crankshafts all the time. We had one customer that *****ed about her car being un-repairable,she's lucky the flywheel that came through the firewall did not kill her,yet she was more worried why the car could not be repaired.Benz built too many turds to spoil the reputation of a few good ones,but after all it was a gas-based "fake" diesel unlike an Indenor"

I really don't know if he's just trolling to get a rise out of the Benz owners, but man, even before I had all the maintenance done on my car, I never once had a shadow of a doubt that something would just spontaneously fall apart on these cars. But the questions still nagged at me, so I felt I'd ask.

EDIT: Okay, I know the cars are old and stuff can break. But I just feel so confident while driving mine.

There are a number of diesel engines out there that are based on the short blocks of gassers. The older mercedes diesels shared some lower end parts with gassers but I am not aware of any of the 616 or 617 engines doing so. I have never heard of any mercedes breaking a crank ever.

The only diesel I ever heard of breaking cranks was the gm 5.7 which was based on an olds gas engine.

They broke other things, too. I don't know if you ever saw the inside of one, but the machining was so sloppy you'ld have to wear gloves when woriking on it or risk a trip to the ER. I don't buy the MB crank story either.

Now THAT engine I have heard was abysmal.

Lack of maintenance, infrequent oil changes, and overheating are all factors that kill any engine. I have never seen a broken 617 crankshaft, but I have seen rods fail from bearing failure that was related to excessive wear and people kept driving it after it started knocking.

My first engine went over a million miles. The crank still mic'd out within acceptable tolerances and was re-used. I am gathering up the documentation to submit to MBZ for my 1,000,000 mile badge.

Yup Dad had a 1979 Delta 88 Royale (not the kind with cheese)...

Most epic fail of an engine ever, engine self destructed with less than 30 k miles.

I think that single handedly ruined the American market for Diesel engines.

Two more questions:

1. Do some people put too much stock in what other people say on the internet?

2. If so, why?

Mine only lasted 4300 miles, it pulled the wrist pin out of a piston while it was idling. The dealer short blocked it but I think all it needed was a new rod and piston. I sold it, and the next owner ran it over 100K miles with no problems. It actually wasn't a bad running engine, but emissions wise, it made the 617 look clean.

Again, I stress that my initial reaction was this guy was either trolling or clearly didn't know what he was talking about. But that's why I put his most unsettling comment on here to be dissected by people who DO know what they're talking about. When it comes to my cars, I'm cautious to the point of it becoming a fault, and will have things fixed even if they make one stray squeak one day.

And when it comes to Benz knowledge, I trust you guys way more! :D

Broken cranks on OM 61X engines are fairly common, if the crank wasn't reground correctly.
The fillet radius on the sides of the bearing surface is critical.
If it isn't done to specs the crank can brake after a short time of operation.