Heat and the 4t65E

[MontyJ]

OK, so if you have been following my other thread on the rebuild, you know there are problems. Here is a rundown:

Cold engine and tranny: Everything is fine, runs like a top.

Engine and tranny at operating temp: Engine runs fine. Tranny slips, mis-shifts (both under load) and sometimes sets 0742. Also occasionally bangs into gear if gas pedal is tramped while struggling under load (ie...going uphill). Sometimes downshifts, only to upshift then drop out of gear then downshift again. At highway speed (65mph) will seem to run fine until a hill or dropping out of the gas at which time the engine will rev with no forward power. If allowed to slow to 45mph it will go into gear and proceed just fine.

I am now noticing a browning of the fluid and a slight burned smell (obviously from the slipping/mis-shifting). Something is very wrong here.

Vital info:
Fluid: Dexron/Mercon
Brand New: MAF, TPS, MAP sensors

What, in the tranny, is affected by heat that could cause this type of activity?

[Rico]

You said the TCC apply valve looked good and you replaced the TCC solenoid, right?
I think it's definitely something in the VB.

[MontyJ]

Yeah, TCC apply valve looked fine, no scoring at all. All solenoids as well as the TC are new.

[Rico]

Please refresh everyone's memory.
What were the symptoms that lead you to rebuilding the transmission in the first place?

[MontyJ]

The original problem was bang shifting. Then it started hesitating between 1-2 really bad. There at the end, it wouldn't go into second at all.

[Rico]

Did you replace the channel plate or reuse the original?

[MontyJ]

I reused the original channel plate, but did replace the gaskets. Umm, I'm probably grasping at straws here, but the parking brake wouldn't have any affect on tranny operation would it? I only ask because on day one of the tranny removal, I went to set the parking brake and the damn bracket that holds the cables across the back frame member broke in half. The parking brake pedal went to the floor, but I got it back up. The brake is not dragging and the brake light is out.

[Rico]

The channel plates are prone to widening/wear of the check ball holes. A ball can get lodged in a hole and cause all kinds of problems. Did you make sure the holes were much smaller than the check balls?

[MontyJ]

I had never heard or read about that. I did not check the size of the check-ball holes. However, thinking back on it, I didn't notice anything that appeared out of the ordinary when I checked the channel plate and I didn't notice any of the check-balls seating "too deep".

[Rico]

I not being an expert can only guess it's something with the valve body after getting up to temperature.

Maybe trannyman could help. I would try posting this in the TEP forum.