tranny overdrie on 2000 Pontiac Montana

my 2000 montana has 140000 mi. on it
transmission works good just no overdrive, what could be the problem

Asked by for the 2000 Pontiac Montana
1 answer
i work at a tranny shop and fixed this problem a few times. the overdrive drum has a short shaft at the end of it with very fine splines. after a while the splines wear out and strip, causing the drum not to spin. the tranny wont blow up, but i recomend getting it fixed asap because of the fine metal shavings in the tranny.