My Pontiac Grand AM GT tends to run hot in stop and go traffic, when that happens the tranny shifts hard. This is an automatic. Any other time she runs fine. Any ideas??
Well hello there Heather,
I would look harder at the overheating issue first, the transmission fluid is also overheating and causing the hard shift. Fix the overheating and hopefully the transmission will return to normal.
1. Check the coolant level inside the radiator…when the engine is completely cool. if you have to add a lot of coolant/water to the radiator, you most likely have a leak somewhere and a cooling system pressure test should be done by your mechanic or a fast lube place to find the leak.
2. Check the electric cooling fan motor up near the radiator. There should be an electric fan up near the radiator (your car might have two fans, one for the A/C and one for the radiator) When the car is overheating, you should be able to see and hear the electric fan motor running. A common complaint with a bad cooling fan motor is engine overheating at idle or slow speeds when there is very little air flow across the radiator.
You could have a bad electric fan motor or a bad relay for that motor. In most cases, its a bad cooling fan motor.
Hope that helps