Car Information:
Chevrolet
Year: 1991
Engine Size: 5.0 TBI
Trans: Automatic

Issue/Question: During very hot summer months, the engine coolant temperature is very high (even over heats sometimes), when the air condition is running while the engine is at idle and/or during stop and go traffic. I believe the engine has 180,000+ miles. Also, when the vehicle is at a full stop and the acellerater is fully pressed down (launched as though at a drag strip), there is a loud thud towards the rear of the vehicle (as though something has spacked the under carriage). I noticed this a week after running over a dead animal (possible deer) in the middle of the road on a pitch black highway.

Answer:
I would check for a bad flywheel/flex plate and a bad fan clutch

Issue/Question: Thank you Larry for your response. I meant to include that it my vehicle is a 1991 camaro rs with a 700R4 Transmission and the radiator fan is an electric fan that’s currently wired to turn on/off via a switch, not thermostat. Anyway, the electric fan remains running as long as it is not turned off via the driver. If my flywheel/flexplate is bad, then why does the loud “smack/thud” upon HARD ACCELERATION sound and feel as though it is at the REAR of the vehicle and not towards the front near the engine?

Answer:
Have you checked for a bent drive shaft?

Magic Mechanic
1432 Lee Road OrlandoFL32804 USA 
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