I have been searching and reading quite a few threads on the coolant and head failure issues on the 87 300 D, but now I have to ask about something that seems not to have been discussed in the past. If some one can direct me to a thread, that would be great.

I was looking in the coolant reservoire on my new 87 300D and noticed an oily sludge on the walls and cap. So I drained everything out of the system, took the res off and cleaned it out and did a cursory inspection of the hoses and the radiator insides (just ran my finger in around the hoses and where ever I could reach) and found no oil residue at all. It seems to be only in the reservoire which is original, I'm sure. Much of the rest of the system is newer including the water pump, radiator, hoses, etc. After cleaning the res I put it back on (wish I'd had a new one handy), filled the system with new coolant, the Zerex 05 as recommended here previously. However, I was in a bit of a panic thinking that the head was cracked which allowed the oil into the coolant. I took it to my very competent indy guy, who did a proper flush, overnight, testing of the coolant for gases, etc. and a pressure test. He came up with nothing. Neither did he find any coolant in the oil. This car has the original #14 head.

My indy says that in diesels, after years and years of blow by the coolant res will have accumulations of oil sometimes. Can this be true? Please confirm or refute. This car runs really well, and doesn't come close to overheating even with the a/c on at idle in 90+ temps. The upper rad hose is soft and pliable and pinchable in the morning when the car is cold.

This site is the best, and has already saved my some hard currency since I bought the car over a month ago. My first MB, and I love it.

Thanks.

DS
87 300 DT