To Whom It May Concern...1995 E300 Oil Cooler

[oilslick]

There's not much info here on the forum when it comes to the coolant - cooled oil cooler on the 1995 E300 so I thought I'd share my recent experience with one.

I just recently purchased a very nice, high mileage 1995 E300. It had been run hot AFTER the previous owner had begun noticing black oil in the coolant. I paid $750 for the car and drove it 52 miles to my house without any issues. It did seem to get a little warmer as I found myself in stop and go traffic after exiting the interstate. I had no previous experience with the OM606 and I was unaware of the coolant - cooled oil cooler on this particular model so knowing it had been run hot and there was oil in the coolant I just went ahead and removed the head. I didn't do any extensive testing. I was looking forward to the learning experience on a new engine model and I didn't need the car, I just bought it to play with. After putting a straightedge to the head I determined that the head was actually warped but not beyond repair.

A few days after I got the car torn apart someone from the forum gave me another 1995 E300 that they had stripped of everything except the running engine and transmission. I decided I'd just use the head from this engine and be on my way. That's what I did. There was some pitting around a few water jackets but it wasn't anything that would create a problem so I installed a new head gasket and the donor head. The car went back together beautifully. I replaced the faulty glow plugs while the head was out and the car would start and run flawlessly. I de-oiled the system thoroughly and put in Zerex G-05 coolant. For the next 150 miles it was pure joy.

I bought a new radiator cap from the dealer and also bought all new fuel lines. When I went to put the new cap on I noticed that the system wasn't pressurized. When I looked into the expansion tank I saw black oil. It was NOT residue from a shoddy de-oiling. I disconnected every line possible and also the block drain when I de-oiled it. I backflushed, forward flushed and every kind of flush I could do to remove the oil. I used dawn dish detergent to emulsify the oil and when I was finished flushing you couldn't find one oil droplet or soap bubble coming out of the engine. I was disappointed. Somehow my new head gasket and head just weren't up to par. The car ran perfectly. No smoke. No missing. Perfect Temps.

I drove the car home and began dismantling the engine. I was going to just go ahead and have the head tested. I had thought it COULD be the oil cooler. I knew the oil pressure was greater than the coolant pressure but I thought surely after the engine was shut down then the coolant would work it's way into the oil but it never did so I thought the cooler was fine.

I'll wrap this story up...I removed the head again and had a compete valve job done and the shop cleaned up the mating surface although the head tested very well. While the head was in the shop I rigged up a way to test the cooler for an internal breach and guess what?........the cooler was breached. Live and learn. Trutfully, I have enjoyed every minute of working on this car and my confidence is going to be high for this car now that the head has been worked over. I removed the oil cooler from the donor car and tested it. No breach! If all goes well I will have the car back together by week's end.



Let my learning experience be a source of education for you if you have a 1995 E300 and you find black oil in your coolant but no coolant in your oil. Check your oil cooler.

It could be worse. I could still own a Ford.