Hi Everyone, I have a 4WD 2001 S10 with a 4.3 and a 4L60E. A while back the original transmission started slipping because of overheating issues thanks to Dexcool sludge buildup. I continued to drive the truck without using Drive so it couldn't get into O.D. Awhile this helped the slipping issue it put more strain on the engine and the intake gasket eventually went bad. It was replaced and the TPS, MAF, ICM, all 3 O2 sensors, plugs, wires and cap. Once the new Trans was put it I noticed the transmission will still slip in Overdrive even though it's new and then the computer makes the line pressure so high it slams into gears once I slow down to lower gears. Once I shut the truck off for a few minutes all is well again. Does the EGR system have anything to do with shifting procedure? What about the shifter position location sensor? Any help is greatly appreciated as I don't want to drive the truck anymore than I absolutely have to.

 

one thing ive actually seen happen before was on a chevy van. place i worked for miss-diagnosed it as a bad transmission. sent trans out to get rebuilt and still the same issue. what was happening was after like 10-20 minutes of driving the van just quit moving, like it went into neutral.

what was causing it was the trans cooler in the radiator was bad, became clogged somehow and was restricting pressure. anyways threw a new radiator in it and it fixed the issue.

not sure thats your issue but just throwing that out there. maybe put a aftermarket cooler in there to see if that fixes the problem

 

I installed a trans temp gauge on my truck. Heat kills trannies

 

Thank you for the responses guys! I have actually changed out the radiator and water pump since having transmission issues. Because the dexcool buildup was so bad the truck was overheating and caused too much pressure to build up causing the plastic radiator end cap to crack and the bearing in the water pump to start to leak. I've been reading in other threads that a vacuum leak of some sort could cause this. My original thought was that it may be the computer itself too. This is actually the 3rd transmission to have slipping issues. The 2nd was from a junkyard and after installing it and seeing that it was also slipping just figured the trans was bad from the get go... Thank you for any other suggestions!
Happy Thanksgiving!

 

I'm at a loss here...

Dexcool caused your tranny slip? Unless the cooler in the radiator leaked I don't see how this could even happen.

When you changed out/rebuilt the tranny, was anything done to the torque converter?

 

In a roundabout way yes. The dexcool sludge built up in the cooling system and caused the coolant temperature to become erratic and often overheated. The cooling system has since been flushed a couple times and temps are rock steady. As we know transmissions don't like heat and because the trans fluid got too hot it caused the transmission to work too hard and slip. The torque converter was swapped out for a brand new unit when the transmission was swapped for the remanufactured one.