Transmission question

[sorny]

My wife has a 2004 Pontiac Montana with 108,00 miles. Recently the transmission started to act up. A few days ago it began to shift very hard during upshifting. It was more of a soft slam than a slip. The next day it shifted fine and we drove it for another 300 miles until today it started to do the same thing. The van has the 3.4 motor with a 4 speed auto tranny. The tranny was serviced at 75,000 and the fluid looks good and level is fine. Does anyone have a clue what might be going on? Thanks, Sorny.

[GMC Jon]

Best to get it scanned and checked for any trouble codes. There could be a shift solenoid acting up. It could also be a problem in one of the clutches or valve body. A road test while checking the transmission data on the scanner, should point you in the right direction.

[sorny]

GMC John,

Thanks for the suggestions! I will be taking the van in to have it scanned on tuesday. (Still no message on the dash) The tranny has continued to act up, but only happens approx. every fifth or sixth time it is driven. Seems to be no real pattern. The interesting thing is that I have pulled over when it acts up, turned the vehicle off for a couple of minutes, and when I restart the vehicle the tranny works fine. Does this point me towards a potnetial diagnosis? Thanks, John.

BAD NEWS Time.


You have a known GM transmission defect in your Montana's tranny. I had a 2002 Chevy Venture Van and my Dad had a 2004 Montana just like yours and the exact same thing happened. It will not show a tranny de either. There is slippage in your tranny due to a hard part failure of which I can't remember the details.

Sorry to inform you but this problem will get worse until it won't shift or will shift goofy and jerky almost like a kid learning how to shift a manual tranny. It then just stops shifting altogether. You might want to prepare yourself for a 2000.00+ tranny rebuild job. GM transmissions, even with extra coolers and 25,000 fluid replacments, never seem to last much past 100,000 miles.


I fixed my problem. I got rid of the van and bought a Honda. My Dad traded his in and made the mistake of buying yet another GM expensive junkster called a Buick Enclave.

[Lusox]

I had tranny problems on a '91 Buick and was advised that it was shot. I was also advised that MAYBE an application of SEAFOAM transmision additive could help. I put in $5 worth of the Seafoam and the car ran fine for another 3 years. Darned if I know why, but it's worth a try for $5.
I also had tranny problems with a '99 Explorer and had it checked out by the dealer who said it was fine - it went completely out the next day so what do I know?

Lusox