I have a 1996 F350 460 V-8 4x4 Crew Cab. Bought her brand new. Only 99,000 miles. I have auto transmission fluid in the radiator. I am confident there is coolant in the tranny too. 4 months ago I changed coolant before going hunting and there was no problem. I have driven about 500 miles since then but I have no idea when the fluids started mixing. 1) what is the best way to flush or servie the tranny with this mix of fluids? 2) should the tranny be ok after I change fluids? This was a brand new tranny install 50k miles ago. Original snapped a shaft about 3 weeks outside of my extended warranty period! Your thoughts? Thanks

Ted DeShong

 

I would say that somehow the cooler that is inside the radiator cracked, and is exchangine the fluids.
You will either need to replace the radiator to prevent mixing again, or you can unhook the radiator from the trans lines and add an aftermarket stacked plate or setrab type trans cooler to the front (i tend to stay away from the single pass coolers)
Both fluids will need to be replaced in the ideal world, but really its the trans the is the critical one. you can get away with pulling the pan off (clean out the sediment from the 50k miles) and then put back together, then add 12 quarts of fluid. Unhook the trans cooler lines and add hoses to them that go down to a bucket. Start up the truck and let the trans pump the fluid into the bucket until you have about 6 quarts in there. Shut off truck and topp off the transmission, and rehook the trans cooler lines. the rest of the water/coolant will evaporate usually once the transmission gets worked and gets up to temperature.
Trans Flush Complete

 

You could also go to a place that has the vacuum to suck out the corrupted tranny fluid. I would definitely get that coolant out of the transmission. Like the poster above a new rad or tranny cooler is in order

 

Thanks guys. Yes I am replacing the radiator, flushing the cooling system and installing new coolant. My biggest concern is the tranny. I will be exchanging fluid in the tranny tomorrow, I just hope there isn't any major damage in the tranny. I am not sure if I should drain the torque converter, or how long I should wait to exchange the fluid again. I like the idea of sucking the fluid all out but I agree that the pan should be cleaned, especially at this point. So I'll pull the pan first, but maybe have the fluid sucked out for the second fluid exchange. Just trying to do it in the proper sequence for the best repair.

Ted DeShong

 

If your biggest concern is for your tranny then the best thing you can do for any automatic with an in rad type cooler is put and external on it. The trans fluid should be changed twice in the first week after this. Then it should be fine.

 

Thanks guys. You are givin me some confidence of the tranny being ok. I read some really nasty things online about coolant in tranny's but I suspect that those situations went on for a long time. When I drained the coolant there was a little tranny fluid floating but not much. Maybe 1/2 cup or so...... But the trans fluid is a creamy strawberry. I hear that it doesn't take much water/coolant to make that happen. I replaced the radiator and all hoses (turned soft) and replaced 6 qtz of trans fluid. Will drive tomorrow then replace 8 qts of fluid. Will drive it for a week and then look for a place that can do a full fluid replacement or I will drop the pan and drain the converter to do a final 100% fluid change. I understand this will be more reliable once the contaminated fluid has been diluted with new fluid a few times. I will let you know in a couple of months how it is doing. Hopefully all will be well. $250 in fluid is cheaper than $2000+ for a rebuild.....