I am a new Mercedes owner. Majorly enjoyed car for 2 weeks before the head gasket blew. This 86 Mercedes 300sdl is in great condition. Has 169,000 miles. Never overheaded. Records show amazing service and care has always been taken. Paid $5,500. I am a DIY'er so working on the car myself...a learn as you go endeavor! I finally found a manual and got down to the head...done a lot of reading from forums to hopefully not miss anything along the way. Carried head several miles to get head resurfaced...guy was clueless about aluminum heads so rescued it before he touched it...Trying another guy now that seems much more knowledgeable. The car was in 'storage' for a couple of years, just taken for a drive around the block and polished on occasionally. Could this 'time out' have cause the head problem? Also, is it worth keeping or will this thing be a money pit? I did a lot of research and the word was so great on these cars that I felt good about it...now I'm having serious doubts...any advice?:

 

Head gasket failures are not common on that OM603 engine, but the early cylinder head castings are known to be crack-prone if overheated. The replacement head castings (which went into production in approx 1988-89) do not have this problem. If the head is crack-free and straight, I'd bolt it back on with a new gasket. If there are any cracks, it's risky to have it welded, as it may crack again... better to located a used late-style head and install that. If the head surface is flat, it DOES NOT need to be resurfaced. If you do get it resurfaced, you will need to measure prechamber protrusion before installing, as described in FSM job # 01-410.

Make SURE you follow the procedure in the factory manual to the letter for the head R&R!! And before starting the engine afterwards, rotate the engine 2 revolutions by hand to verify the camshaft timing is correct (lining up the marks on the balancer, and on the cam tower). If you haven't already done so... post over on the PeachParts diesel forum, your question will get a LOT more visibility over there.

Diesel Discussion - PeachParts Mercedes ShopForum

Also read this buying guide, it's primarily for the 1987 300D/TD, but all the information about the engine applies to your 300SDL as well.

 

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