I have a 96 f-250 with the 7.3l with 110k miles. I installed a new water pump recently and when the vehicle is Idleing the transmission temp rises slowly and as soon as I start moving the temperate slowly returns back to its normal temps. any suggestions on what would cause this?

 

Air flow through the Radiator cooling the oil down possibly...

If your trans is overheating may want to put another cooler on it. Also, check Line pressure. Check fluid level. Don't overfill it.

I'm not a expert on transmissions.

Mark might chime in here later on once he gets on...

 

Did it do this before the new water pump?

 

No it never did this before the water pump went bad. When it went bad (impeller shaft barrings and seals) is when I first noticed the higher than usual transmission temp as I was driving home so I could work on it. Then after replacing the pump the engine temp stays where it use to be, but the transmission temps still act up. For a basis no load going down the road or sitting before the new water pump the temps always stayed at 140-150. Now Idleing with the new water pump the highest I've seen the temps get to is 195. And cruising it can slowly go back down.

 

You need to run a flow test on the trans.

Warm up the trans to about 150F. Remove the cooler line where it attaches to the rear of the trans. Get two buckets.

With the removed line pointing into one of the buckets have someone start the engine. Leave it idling in park. Once the flow is steady move the line to the second bucket for exactly 15 seconds, then back to the first bucket, and turn the engine off.

If fluid sprayed out of the rear of the trans it fails the test. If there is less than a quart in the second bucket it fails.

If it fails it means the cooler lines or coolers themselves are restricted. You would need to find and fix the problem.

 

I was finally able to do the transmission test and it ran through almost two quarts in 15 seconds. So I believe it passed.

 

i would much rather have 195F trans temps than i would 140F trans temps.*

"According to Ron Sessions, author of the Turbo Hydra-Matic 350 Handbook (HP Books), the ideal operating temperature for transmission fluid is between 175 and 225 degrees Fahrenheit."

your transmission is now running at a more optimal operating temp.

one of the more widely misconceptions about the auto transmissions is; the cooler the better.it's just not true.just like your engine,there is an ideal operating temp.
therefore,your thread title is incorrect.it should read: E4OD running at optimal temperature.


* temp reading @ the test port.