Transmission cooler in Radiator Failed

[Jay White]

Had the transmission cooler that's built into the radiator fail and in turn it dumped transmission fluid into the cooling system. I have drained the cooling system and I'm installing a new radiator. Question is, what is the best way to get the oily residue (from the transmission fluid) out of the cooling system within the engine. My transmission guy said to flush the system repeatedly using a radiator flush (basically install new water and flush, drive the car for a day, then drain the system and repeat as many times as required). Is there a better way to do this?



Also, my transmission guy said it appeared that possibly, a little coolant water might have gotten into the transmission (with the transmission being at a much higher pressure that the coolant system, I really don't see how that could happen). He recommended multiple flushings of the transmission too to remove as much of the contaminated transmission fluid. Any one have this problem and can make comments or suggestions?



Thanks for any and all help.

 

[Lloyd Ledford]

is the trans fluid milky?, if not, you're probably ok. just make sure fluid level is correct.

 

[Jay White]

What little bit of tran. fluid is left does not really look that way to me. I will still get it flushed at least once with a new filter.

 

[scott degroot]

T0 get the oil residue out of the cooling system I do 2 flushes. First drain the cooling system and then put about 2 cups of liquid dishwasher detergent in it and fill it with water and let it run for about 1/2 hour. The liquid dishwasher detergent will break down the oil and it is low sudsing. After that drain the system and put in about 1/2 gallon of simple green, fill with water and pun it again for about 1/2 hour. after that I do a clean water flush and then fill with coolant. Check all of the rubber coolant hoses very carefully for swelling as the oil will play hell with them.

 

[John Zuber]

Not sure how the trans fluid being pumped through the radiator could be at a pressure level equal to or greater than the coolant pressure, when everything is hot. Heck, the trans doesn't even have a sealed dipstick cap, whereas the radiator is sealed and pressure is quite high. I would think the trans fluid pumping pressure would be low going to/from the cooler section. Does anyone here know?



By the way, how did you discover the problem? Maybe a simple cleaner/degreaser and distilled water would work just fine on cleaning it out. The key is to allow the temp to reach normal operating temp, then drain and flush with clean distilled water.

 

[Yardsale]

I could be wrong, but it seems that, with a 18 lb radiator cap (or whatever), that would be the maximum pressure, and this doesn't seem high.



When the coolant is at ambient temperature, pressure in the coolant system is from the water pump, and the radiator is bypassed (to aid in warm-up); the transmission pressure is relatively constant.



When the vehicle cools, transmission fluid leaking from the radiator cooler can be sucked in to the radiator, just as coolant in the overflow reservoir is pulled back into the radiator.



This is kind of interesting (goes both ways):

 

[Jay White]

For those that asked, I had some slipping in the transmission from a standing start. I went by my local transmission shop thinking that my torque converter was failing and the mechanic said that was a possibility but there were other potential causes to the slipping. He asked about the level in the transmission and I informed him that I hadn't checked it because there had been no leaks on the ST. After checking the fluid at the shop, the level could not be read on the dipstick. I asked where the fluid had gone and the mechanic said that it had to be in the cooling system. He diagnosed that the transmission cooler had failed and the transmission fluid had been pumped into the radiator. He then recommended I replace the radiator and mentioned I would have to flush the system many times to clean it up. He also said that he thought coolant water had entered the transmission and probably multiple transmission flushes would be needed to clean that up but offered no guarantees that I wouldn't have future transmission problems due to the water getting into the system.



He added a quart of transmission fluid to the transmission to get me home and off I went. At home, after letting the ST cool down a little, I opened the radiator cap, which still had a slight pressure on it, and was sprayed by a warm water mix that looked like Pepto Bismol. Most of that quart he had just put in had been pumped into the radiator!



I have since replace the radiator and flushed the cooling system at least 4 times with plain water, each time getting a large glop of pink sludge but that is slowly decreasing in volume with each flush. Right now I have a Prestone Coolant Flush in the system and will leave it in for 3 days before flushing the system again. I plan on running some simple green through it as a final cleaning.



I had the Transmission flushed today and the color of the fluid improved tremendously but still has some very slight pinkish spots to it. Will most likely flush it again in a day or two, then wait a week or so and remove the pan and replace the filter and the fluid. Hopefully this will solve my problem for the most part.



Any other comments are welcome and appreciated.

 

[scott degroot]

The Pestone flush won't do anything for you as it has nothing in it to break down the oil. The method I describe in my above post is what we use on Ford diesels when an oil cooler decides to let go. Talk about a cooling system mess. Anyway this method works incredibly well. As far as the trans goes that shouldn't be too much of an issue. I had a flood car in last week that had filled the trans with water and the customer had actually driven it. I dropped the pan and changed the filter then flushed the trans, drove the vehicle for about 10 miles and then flushed it again and had no more traces of water in it and it operated fine.

 

[Dreman]

Not sure how the trans fluid being pumped through the radiator could be at a pressure level equal to or greater than the coolant pressure, when everything is hot. Heck, the trans doesn't even have a sealed dipstick cap, whereas the radiator is sealed and pressure is quite high. I would think the trans fluid pumping pressure would be low going to/from the cooler section. Does anyone here know?

The main pump in the transmission picks up trans fluid from the pan, pressurizes it so the transmission can use it, and sends it to the radiator for cooling. There is an isolation chamber in the radiator that the trans fluid passes through that has coolant on the outside and trans fluid on the inside. Not only do they never meet, but the pressure of the trans fluid also never reaches the coolant. The trans fluid heats up the isolation chamber from the inside, dumping it's heat in the process. The coolant cools the chamber down at the same time from the outside. The heat from the transmission has now been transferred to the coolant, which is then cooled with all the rest of the coolant with the air passing over the radiator fins. Just like the outside air never touches the coolant, or it's pressure, the trans. fluid never touches the coolant. It's a separate system inside the radiator. When they meet, things go wrong, and the radiator has to be replaced.



When the transmission fluid has passed through the transmission, it's pressure is released, and done it's job, it is dumped into the trans. pan for filtering and re-use. The trans. pan is vented and is at outside air pressure, which is why the dipstick doesn't spray trans. fluid all over you when you pull it out.