Jim Grant's Tech Tips
‘94 Pontiac Grand Prix, Flustered
After rebuilding the motor in my ’94 Pontiac Grand Prix 3.1 v6 we were able to turn the motor by hand while the motor was out of car. Now the motor is back in car and we can’t turn it by key or by hand. What can be the problem? We tried everything we could think of.
Your Pontiac most likely has an automatic transmission. When you removed the engine the torque converter for the transmission slid forward about ˝ “ and then turned just a smidgeon. That ˝” and smidgeon is just enough to cause the drive notches on the torque converter to come out of the front pump of the transmission. When you reinstalled the engine you would still be able to align the bolts to bolt the torque converter to the flex plate but when you tightened the bolts to the bell housing the drive notches on the torque converter are now pressed tight against the front of the inner gear of the front pump of the transmission. The gear is pressed tight against its housing. The end result is an engine that will not turn over. If you’re lucky you can remove the engine and reposition the torque converter’s drive notches correctly into the front pump’s gear. If you are unlucky, you’ll need to replace the front pump of the automatic transmission. Isn’t learning about cars great fun?