Transmission Temperature

[69sonnet]

I have a 92 xlt with factory tow package. The automatic transmission was rebuilt and all the new heavy duty parts put in last year. I had a temperature gauge added which the sensor is on the line just before it goes to the radiator and trans cooler. The temperature will reach 220 going up the mountians not towing anything. It went up to 260 towing a 400lb trailer on a cool day. I have a 4000lb travel trailer but I am concerned about towing it due to the temps I am seeing. Any advice or is what I am seeing normal?

 

[Jason_25]

Wow that's way too high of a temperature. Ford says normal operating temperature is 150-170 degrees. I have never seen mine go above 165 although I have an RV tranny cooler.

I recommend you check the fluid level and add the largest auxiliary cooler you can fit.

Edit: What is the normal engine temp? If your engine is running hot, your tranny will get hot too through conduction where the tranny meets the block and also where the tranny cooler lines run into the radiator.

 

[69sonnet]

I did have the sensor on the return side for awhile and the temps were in the 140-170 range and in the 190-230 range when towing the 4000lb trailer.

 

[410Fortune]

the sensor should be on the return line, right before it enters the tranny, since this is the fluid the tranny starts with this is where you monitor it.

I am not wsurprised the temo was that high since you have the sensor on the fluid before it gets cooled....

A good trans cooler should drop that sucker 80-90 degrees..............

 

[Raceit]

Wouldn't you want to measure the temp soon as it comes out of the tranny to get an accurate reading? Coolent temp is measured in the engine as opposed to a return line from the raditor.

I dunno... that's just my uneducated thoughts on it.

 

[dogfriend]

Ideally you want to know what the temp is inside the transmission (highest temp).

On the 5R55E, there is a thermistor mounted in the valve body that transmits the temp to the PCM. The PID is TFT (transmission fluid temp) and the values in the PID reference chart are 110-210 Deg (I am assuming Deg F, they don't say). I have read before in various places that you should keep ATF temps below about 170 F - the fluid breaks down rapidly at temps higher than this. Syn ATF is supposed to be more resistent to heat degradation.