I recently made about a 600 mile trip in my car (700r4 trans). I had no problems during the first 600 miles other than the engine running hot. The 600 miles back were rough. The engine was constantly running hot, it wouldn't stay below about 235 or 240 the entire trip other than when I stopped to run water over the radiator and trans cooler. This was during 100+ degree weather which probably contributed to the problem. After driving about 300 miles or so, I stopped at a gas station. As I was going through the lower gears, I noticed a very bad slip. 1st wouldn't put much torque on the ground, and the shift into 2nd was so bad that I could not tell when it actually shifted. 2nd gear was the worst, the tranny slipped all the way through 2nd. The 2-3 shift wasn't bad, but it did feel more mushy than usual. 3rd gear seemed to slightly lack power. The 3-4 shift felt normal as did 4th gear.

I assumed that this only because the tranny was hot. I got home yesterday and drove my car to work today. I figured the tranny would be back to normal after cooling off, but it wasn't. It still has the same problems I described above. I checked the fluid and it is red and at the correct level. I know next to nothing about transmissions, so can anyone tell me what might have happened?

 

Fluid overheated, clutches deterioriated. Needs a rebuild. Check the TCC operation when you put it back in.

 

My first thought is the torque converter, because 4th feeling normal could be the lockup still working correctly. Got a working, semi-accurate tachometer in the car? What's the flash stall? Does it behave any better with manual shifting?

 

Yup; most likely the "running hot" problem was caused by the failed transmission, not the other way around.

Doesn't too much matter what the details of the trans failure are now, though. Needs a rebuild no matter what. Replace the TC as well of course.

 

I figured that it needs a rebuild now. The sad thing is that I just put this transmission in not even a year ago. It was a Goodwrench rebuilt and advertised on craigslist having fewer than 5,000 miles on it.

I still have my old 700r4, so I think I'll rebuild that one since it's already out of the vehicle. One important thing about it: I was told that when it was rebuilt the first time, one or some of the parts came out of a different model 700r4. After being rebuilt, that tranny would always slip between 3rd and 4th in the 40-50mph range. It would only hold 4th if the rpms were high enough. With this in mind, should I even bother to rebuild that tranny? I would hate to rebuild it and then have problems because one part was incompatible. The current is still driveable, so I plan to keep driving with it until I rebuild the old 700r4.

 

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