There's no thermostat in a 4R100 trans. There is a temp sensor that reports temp to the PCM, but there is no flow control from that. There is also a sensor somewhere that is reporting temps to your gauge.

 

Where is the trany sensor located? Flow ! Did you check flow? Good to see your using the i/r gun its a good trouble shooter. You talked about you had your trany rebuilt! Can you have them look at it might save you some money.Comparing the trany temp guage to I/R gun was it close? One thing to remember when using I/R gun is it wont read correct on shining reflecting surface.I spray black paint on the shining surface should be good to go then.

 

Thank you!

Yes I checked flow, I did the diesel site test and my results equalled the dieselsite results in replacing the bypass tube. The IR gun wasnt exact to what my guage said but it was close. The trans temp sensor is in the test port. Im giving up, looks like monday and tuesday it will not snow, im going to try to get a trans place look at thats right by my house.

The trans was rebuilt summer of 07, then in spring of 08 it went bad again and they rebuilt it under warranty, it took them 2 weeks to finally figure out the problem, and here we are another 8 months later with more problems. As of this past monday they claim to have 19 other cars that need to be worked on, there is just 2 tranny guys there to do the rebuilding work. They made me a pretty good trans but there are problems left and right and the trans is not something i want to be hiccupping randomly. Im pretty frustrated that I spent about $2800 and now ill have to spend another chunk to get it right. My Dad has had transmissions rebuilt there for years and years without any issues, guess i was the lucky duck.

So last night while plowing, the frigid cold returned, it was 1 degree out and my trans kept overheating. I did my best to keep it below 200 and did well. it would slowly go bown while driving but it would only drop about 3* in 2 miles.

I will keep you all posted as to what the trans shop finds, hopefully they wont have to pull it out saving me more money.

The Ford Part # for the Bypass Valve is: 2C3Z-7H322-BA

I really appreciate all of your help, I was at least able to plow and thats all I wanted. I was able to bring in a couple thousand which looks like it will head right back into the truck. If I werent able to earn what I did I would never have been able to afford reparing the trans.

Thanks again!

 

Doug If you do go to ford for repairs have them take an oil sample then have them show you the trany filter. You will be looking for metal or paper take your magnet Look closely for metal shavings in the filter THEN KEEP THE OLD FILTER. Oil sample will help you in court if it goes this far! When you did the flow test did you flow fluild past the cooler? Make sure its going thru the cooler AND BACK TO THE TRANY. Im correct your truck engine is not overheating? JUST trying to cover all bases for you.

 

Thanks, will do.

I just got the plow off and I touched the in-side of the stock cooler and its nice and warm. I cant get my hand on the other side but tomorrow im going to get at it and see what going on. It might be a clog on the return side line or the aux cooler. The trans pump should have enough pressure to pump through a stock cooler and an aux cooler right?

If I have to perm remove the aux cooler, i am fine with that, just want it back to normal operating temps. would I be better off using the aux cooler or the stock cooler? They are both brand new.

 

Yes, it does, if there is no additional restriction. If there is the bypass is going to open and there will be no flow to the coolers, which will overheat your trans.

You have a restriction in the cooling circuit which is causing the bypass to open.