I have a 2004 Dodge Neon with 130k on it. One day I was driving and it started smoking and the temp gauge went to H and the bell was dinging. I pulled over and looked under the hood and all the hoses were ok, the cap was still on and the radiator was not leaking. But, the firewall was soaked. At first thought it looked like the heater core had failed, but I did not find any evidence inside the car of such. After looking at the repair manual on www.alldatadiy.com, I realized that the core sits in a tray that is supposed to catch the fluid and drain it back outside. So, I rented a car trailer and towed it back home to begin work. I did a pressure test and the pressure held for 20 minutes. Then I started thinking that it just boiled over into the recovery container and that would explain why the fluid was all over the firewall. So I flushed and refilled the radiator, started her up and all seemed fine, no leaks. Temp held right in the mid to low range of the gauge. I thought the problem was solved.

Then I took her down off the stands, then when I put her in reverse, she paused for about 5 secs and then shifted into reverse. I thought, hmm, then put her in D and the same thing happened. I shut her down, pulled out the tranny dipstick, low and behold, there was pink bubbles in the fluid.

Aha, that explains why the pressure test was fine, the cooler in the radiator failed , but not leaking to the outside, but in the tranny.

So, my question is....When I replace the radiator, cooler supply lines and clamps; would a simple flush of the tranny fix the issue or is a rebuild in her future? Also, what is the best recommendation for replacing the fluid in the tranny, power flush or shade tree mechanic fluid exchange?

 

Replace all of that and i would just flush the tranny. Fill it back up and see if it works. I bought this car with 36,000 miles and didn't change the tranny fluid till 110,000. With no metal shavings. It's a good tranny so i'm guessing just flush it.

 

Yeah, don't shade-tree anything with it. Take it somewhere that will geniuinely power-flush it out. But keep in mind, with 130k on it, your clutch packs aren't exactly new anymore... and since you overheated the bejesus out of it and foamed the fluid up, I would suspect your clutches took one hell of a beating out of it.

The flush-and-fill may seem fine for now, but I would prepare yourself for a new tranny or rebuild in the near future...