I recently bought an '87 300SDL with 150000 miles. It ran great for about 10000 miles. But now its gotten rough idling immediately after starting and I'm getting about 1 quart of diesel fuel in my oil after driving about 200 miles after an oil change. The oil level dash light comes on and the oil pressure drops slightly (to a little above 2). I've limped home and changed the oil and filter and it happened a second time. The MB service facility (not a dealer) changed the injectors but that didn't help the rough idle or the fuel in the oil. They now feel it might need a new diesel fuel injector pump (+$1500 rebuilt from MB + labor), but before I do that I want to feel sure it'll fix the problem. Can anyone tell me how the injector pump can release fuel directly into the oil? Is this common on this motor (603.960)? Is there any way to test the pump for this problem? Any other insight as to what else could be causing these problems?
Thanks, Heins

Heins;
You might want to check the supply pump first. That is the small pump on the side of the main IP. It has a line going to and from it. Very rare for an inline pump to dump diesel in the oil. It is very simple and cheap to replace. IP....big bucks.

Heins;

I should have mentioned that it is common for the supply pump to leak into the crankcase. It is driven from the IP and has direct access to crankcase oil the same as the bottom half of the IP. I believe it has a diaphram that can develope a leak.

Heins,

The symptoms you describe seem to be more indicative of a head gasket leak, which is not uncommon for this vehicle. I had a double whammy with mine a few months ago and replaced the head gasket as well as the IP. The new head gaskets are much more durable than the originals. Though I never enjoy spending big $$, the car runs beautifully now. Also had the head inspected, which is a no brainer, as it is prone to cracking in perhaps <5% of vehicles of this vintage. Fortunately, it is in excellent condition. Head gasket replacement will run ~$1000.

Goldenbear,

Correct me if I'm wrong but I have to disagree. The head gasket keeps engine oil and coolant separate for these fluids to pass between the engine block and the cylinder head. No diesel fuel should be passing through the engine oil or coolant galleries. The diesel fuel in the oil problem described in the original post would mostly likely be coming from the injection pump area.....most likely where MREID indicated at the supply pump next to the injection pump.

Herb
'82 240D
111,000

Herb,

You are correct. That's what a get for typing on the fly. :)

My diagnosis of his symptoms as being related to the head gasket stem from his statements re: rough idling/starting and loss of oil - which were the precise symptoms that lead to the replacement of my head gasket. I support mreids theory behind fuel in the oil. I'm afraid we may have two separate issues here. :(