Recently, an old friend had a OM603.971 engine failure. I am trying to understand it so I can help him decide what to do. I have read everything I can find on the Diesel Forum. If you, like Jack, have also experienced a 3.5 liter OM603 failure and repair or know about them, please tell us how it happens.

Jack's car is actually a 1992 300SD with 82K miles. It is from Oregon but Jack moved it to California. It as an excellent all original garaged car. Suddenly it started smoking huge amounts of blue smoke and clattering. He took it to Mercedes-Benz dealer. They compression checked each cylinder via the combustion chambers - all good. They suspected a turbo oil leak. They took off the turbo and saw wet oil in the exhaust side and ordered a remanufactured turbo from Germany. When they installed it - no change. Their conclusion is that the car has a defect inside the engine, so it needs a remanufactured engine for $13,000. Jack is has plenty of money which he has not accumulated by letting the MB dealer's service department have their way with him every time he comes to the shop.

I am not a mechanic, but if one wanted to see if the engine was drinking oil from the turbo, would you not simply remove the air pipe between the intake manifold and the compressor and let the turbo run while the intake aspirates normally ? If oil is only leaking out the drive side, the cold engine wont make blue smoke. I have not seen any threads on exploding turbos, so I dont think it would over rev.

When I asked the service advisor(who is paid by commision rather than salary) if they ever removed heads from any engines at their shop, he said no. I suppose that labor charges being equal that the profit margin on an engine is probably a bit more than on a head gasket.

What actually happens with these engines?
Is the bending always caused by hydraulic lock from fluid in the top of the cyclinder?
Which is the offending fluid - fuel, oil, water?
Where does it come from?

There is actually what appears to be a known defect in the head through 3-31-94 shown in the offical MB repair manual, I will try to attach the pdf article. It shows a "known to happen" oil leak into the #1 cyclinder. In fact, in the repair manual it says if the engine is smoking blue and clattering, that is the likely cause.

Has anyone actually ever heard of a 3.5 liter OM603 with only a bad head gasket?

With only a bent rod, can the engine get enough oil up from the bottom to burn blue smoke?

Does this sound like a "typical" 3.5 liter OM603 failure?

I will appreciate your input and I will also try to get someone to open the engine to see what we can see and get back with the results.

Thanks

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JMF