Good Day.

I am wondering how normal it is to get a little constant puff of smoke coming out of that valve cover weep hole on the right rear side of the valve cover?

As my profile indicates I have a 1985 280GE that was converted to a diesel using a (1992 I think) OM602.961 turbo diesel 2.5 litre engine out of a European W124 series car. I have retained the stock 280GE air filter housing and element and made an adaptor U-pipe to connect this up to the input of the factory OM602.961 turbo.

I do have a PCV arrangement feeding the overpressure in the valve cover back into the intake at the air filter housing.

Any ideas? How much blowby is normal? My engine seems to run well. My cooling issues under load have been fixed with the use of a correct 250GD radiator shroud as my old one was modified poorly.

Thanks, Roman

Good Day. Unfortunately I do know the problem now. It is a craqcked aluminum head and bad head gasket.

Looks like it is very common on these engines (OM602 and OM603) 5 and 6 cylinder engines with aluminum heads. I didn't know this before.

I will have to replace the head or engine. I don't know which way I am going yet.

I hope your problem isn't as bad but in my case the blowby from the weep hole got a bit worse over time and now my G Wagen is not drivable. I have large clouds of white and smelly smoke coming out of my exhaust now under any throttle application.

At least this explains the slight engine temperature variations that I have had for about a year now. It happened that every time I went up a long hill the temperature climbed up right away and I could never figure it our. Lately even at highway speeds on the flat roads I would get a temperature spike and then when I stopped at a light it would cool down again. Are you experiencing any of the same issues?

Regards, Roman

Good Day Angelos.

When you remove your oil filler cap on your valve cover with your engine running, do you get some positive pressure and maybe a louder sound and a steady puff of smoke out of there? If so I would suspect blowby either from your rings or perhaps one or more of your valves. In my case I also have the plastic tubing going from the valve cover to the intake system (after the air filter but before the turbo). I think this is a normal part of the PCV system (positive crankcase ventilation system)

Good Luck, Roman 

Good Day Angelos.

I am guessing that it is either your head gasket or your head. Your head could be warped or cracked or you could simply have one or more valve or valve seals that are faulty. It sounds like you and I have similar problems. I won't be able to have time to remove my head for another 2 weeks. Then I will know for sure whether my problem is head gasket, head or valves and valve seals. I'll let you know.

I hope your problem isn't the head. That won't be cheap. My head is going to be about $3800 in parts alone as no-one sells used or rebuilt heads for the OM602 or OM603 engines with the aluminum heads. If that's the case I will be looking for a new engine fast. I have a couple of leads. So far a good lead from this forum is the best one.

Cheers, Roman

Quick update on my head / temperature issues...I did finally find the time to work on my diesel.

My wife and kids were on holiday for 4 days and instead of joining them I took the time to finally fix my head issues.

I am not too smart since it was my wedding anniversary but it's hard to find uninterrupted time these days.

I'll trade the fixed diesel for sleeping on the couch a few days anytime.

It turned out to be the very common head gasket issue only! NOt the cracked head that is more common on OM603 engines.

Thank goodness. The original head gasket isn't well reinforced between the water journals and cylinder #1. The replacement gasket kit by ELRING (also German made) is much higher quality. With all new gaskets and new head bolts, coolant, an oil change and a bit more I am now good to go!

The hardest part by far was removing those awful little dowels in the head that hold the timing chain plastic guides in place.

I'm all smiles now.

ROman

Roman

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The conversion was done in Germany before I got the truck so I can't be sure if the W124 sump / oil pan was used or if a proper W460 specification oil pan was used.

I never bottomed out the oil pan on the front differential but then I never really abused the truck. The truck did have the factory heavy duty springs that were 50mm higher which definately would help with oil pan / differential clearance issues though.

Roman