Hello all,

I have a 1985 300SD (200K) that I just purchased and decided to do some basic routine maintenance on the transmission, but while I was draining the transmission fluid, I noticed that it looked brown or even green. At closer inspection, my drain pan looked green!

My guess is that the radiator is leaking through the transmission cooler and contaminating the fluid. The car seems to shift fine before. It shifts through all the gears and I didn't notice any flaring between shifts. It is kinda sluggish from a stop like it isn't shifting all the way down into first at a start, but I do count 3 shifts sometimes and other times I will start with the selector in "2" and it will not shift until I push it into "3" as if it didn't start in first. Anyway, I am a little more worried about the coolant contamination at the moment.

Has anyone ever had this happen?

I put a leak tester on the reservoir tank and pumped it up to 10 psi where it slowly leaked out, I would say a 1 psi/min or slightly longer. Not sure if there is a specification on this or what you guys think.

I also tried to plug one side of the transmission cooler inlets and pressurize the other while someone was looking for bubbles in the overflow tank. No bubbles, but I am not confident I got a good enough seal to really test it.

The radiator looks fairly new to me, I am trying to contact the previous owner to see if he knows if it was replaced recently. Maybe it was replaced and the fluid was never flushed?

Currently, I changed the filter and gasket and refiled with fluid. The car still shifts good, but I am not sure what to do?

Does anyone have any input? Any help is greatly appreciated.

Attached is a picture of my drain pan removed from the car.

Thanks,

Keith

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1985 300SD 200K