2003 Silverado 4L60e Trans slips upshift 2nd to 3rd

[dhusband]

Truck has 222000 miles on it. With gentle acceleration not noticeable, with maybe half throttle rpms increase for say one second or two and then shifts smoothly into third, However at full throttle with the shift coming at 55 mph or so, it shifts perfectly with no slip. It also acts the same manually. I had asked my mechanic about changing the fluid and if it could fix the problem, he said, "well it could help or hurt it." After thinking about it, we decided to change the fluid. He did a full flush and cleaned out the pan which had lots of sludge in it but no pieces of metal in it that would seem to indicate a major internal problem. It doesn't seem to have made it much worse if at all, but did not fix it. A friend who has some knowledge thinks it could be the torque converter. I am wary of AAMCO, and I would appreciate any insight that could help me make the correct decisions about getting it repaired. Last fluid flush at 125000 Miles

 

[Nasty02Avalanche]

When I was a kid, a gentleman that owned a used car lot once said to my dad, you can see into the engine just as far as I can!

The reason I bring this up is because you are asking for a diagnosis over the internet for a problem that you described, that could be one of a number of things.

My gut feeling tells me to say that you have a cracked Shell, but there is no way of knowing that without taking the transmission apart and looking.

My heart says that it is a worn out plate, between the valve body.
Usually a check ball modulates in the passageway and wears a hole into the plate and then the check ball doesn't do what it is supposed to do.

That is a heck of a lot of miles for that model of transmission. I am very surprised that it has not failed already.

Probably the cheapest cure, if you were not planning on keeping the vehicle would be to just get rid of the vehicle.

If you were going to keep the vehicle, I would suggest that you find a good used transmission and just pay to have it replaced.

Trying to rebuild a transmission with that many miles on it, is going to be very expensive. By the time you buy a new torque converter, you are probably looking at spending $1000 to have it rebuilt and $500 to have it removed and reinstalled.

A friend of mine that was a GM transmission mechanic for many years once said to me, did you think that just replacing the fluid would fix the problem?
Once damage is done to an automatic tranny, it never seems to get any better. There could be worn bearings or other issues, no way of knowing until you pay someone to take it out and take it apart.

Is it a 4x4? Did you also change the fluid in the transfer case?