I found how the water was getting into the Trans. I believe. The Trans dipstick tube had a good size gouge in the side on the tube, about 1.5 inch long. When hosing off the engine or driving in the rain, water would have entered. Bad thing is it was most likely letting in more than just water. Road debris ect. Soldered it closed and took it to a shop to flush the trans. I haven't lost any radiator fluid from the now open trans tank on the radiator so I think it was ok, but I will still leave the aux trans cooler on since it's mounted already.

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1982 240D 370,000 daily driver, great car!
1983 300SD
1995 350SD gone to rod bending heaven.
1986 300SDL should have never sold it.
1995 2Dr 4x4 Tahoe with a highly modified 6.5 turbo diesel, 6in lift.