I drive a 1991 model 740 wagon with the BF230 engine and 230k miles - 50k miles into my 3rd fuel pump.

Yesterday I found that coolant had leaked into my transmission fluid through the transmission oil cooler in the radiator (I think this resulted from putting in a used radiator that was damaged).

I think it was approximately a half liter of coolant, and I noticed the problem within a day (the transmission fluid took on the hue of a strawberry milkshake).

Before going to bed, I replaced all of the transmission fluid - first draining the pan, and then pouring a couple of gallons of new fluid in as I ran the motor, draining fluid from the oil line that goes to the radiator until it ran dark red.

This morning I drained the coolant (which had approximately a half liter of transmission oil in it), and replaced it with water mixed with 1/3 of a cup of powdered laundry detergent. I connected the two oil lines together and drove it today for 12 miles to work and back. The transmission works normally. It ran at about 80 deg F without the cooler (it was a cold day).

Soon, I will replace more transmission fluid (draining at least another liter
from the pan).

I will also flush the cooling system with water, and then standard radiator flush solution, and then again with water before replacing the radiator (with a new Nissens radiator this time).

I'm wondering if this brief exposure to water will lead to an eventual failure of the friction surfaces in my transmission? Any thoughts? I will have this transmission rebuilt if this happens - I love this car - even though it needs a new catalytic converter (its 3rd).

Perhaps you are wondering how I came to need to replace my radiator.
The original transmission in this car failed on 1/1/10. I found one from a 92 car in a bone yard with 117 k miles and clean fluid. Put it in without a transmission jack (with my athletic son's help). Drove a mile before the torque converter that came with it failed. Bought a refurbished torque converter from Transtar and a transmission jack from Harbor Freight Tools (my son was back at the University).

I read all the material on this site about changing a transmission. Unfortunately, I didn't support the motor as I unfastened the transmission support the second time (before engaging the transmission jack) but I had my wife observe to insure that I didn't thus mash the distributor against the firewall - but I did thus strain the upper radiator hose, and cause a hairline fracture in the plastic end-piece of the radiator.

My attempt to glue it did not succeed. The replacement radiator came from the same car as the transmission. It was partially full of an oil/water emulsion - I should have pressure tested the oil cooler before installing it - but I thought it might have been oil from the crankcase of the old car.

Surprised to find that the 92 radiator was 4 inches wider than the 91 radiator it replaced! It fits (but required removing the thermostatically controlled intake air switch (which hasn't been plumbed to the exhaust manifold for a decade). I've ordered this bigger radiator which has a bigger transmission oil cooler (I pull a pop-up camper).

I also put the steering rack from the 92 car into mine. Now I'm enjoying power steering again for the first time in two years!

I really appreciate the wonderful Volvo information that this site provides (especially the 7xx/9xx FAQs).

Thanks,
John