Tranny Problem

[01montana]

Sorry another post about a transmission problem, but here goes.

Our 01 Montana has about 48,000 miles and just lost 4th gear. The check engine light is not on and the code scanner did not picked up any stored codes. In fact according to the scanner everything with the transmission is fine, but it is definatley not shifting into 4th. At 60MPH the tach is reading about 3K RPM, that's a lot higher than normal.

Has anyone else had this problem and what did it turn out to be?

Thanks in advance.

Mario

[GTP Dad]

Are you certain that the car isn't shifting. It may be that the torque converter isn't locking up. Sometimes the torque converter solenoid goes bad and it will not engage resulting in more slipping and higher rpm's. You may want to take it to a tranny shop for diagnosis only.

[01montana]

Yes I'm sure it's not shifting. When it's at highway speed in D and I shift it to 3 there is no change in engine speed and I do not feel a shift from 4 to 3. Also wouldn't a bad torque converter solinoid throw a code? I'm saving the tranny shop as the last resort I've heard so many horror stories about those places. I had a GM tech scan it and test drive it after hours last night and he was puzzled by the scanner results and the test drive. He is supposed to be asking the dealerships' tranny expert about his findings today. So maybe I'll have their answer tonight.

[GTP Dad]

Not necessarily depends on if the solenoid is bad or the torque convertor. This tranny is electronically controlled and it may just be a solenoid that changes the gears between 3rd and 4th. But that should throw a code. Can't really say what is going on based on what you have said. I hope you get it figured out. Please post when you get a final diagnosis.

[01montana]

Ok, just got the car back last night. It turns out it was the 4th gear shaft and not the whole transmission. Initially it looked really bad as the pan was full of metal shavings. Appearently this is a new common problem with GM trannies. The dealership had a GP they were working on with the exact same problem, and they had done a Montana a week earlier. I have the shaft in front of me as a souvenier of this adventure. It's about 10 inches long with a big gear type thing on one end and small splines on the other. The splines are what wore off and they are mostly gone.

So if this happens to anyone else check the 4th gear shaft it cost way less than a new transmission.

Later,

Mario