Possible causes for GTOs overheating
I read a few posts about people having overheating problems.
I have a shop in my area that specializes in old pontiacs, specifically GTOs. The owner has been racing GTOs for over 35 years. So I asked him what the most common problems could be and here's his responses:
1. Some aftermarket water pumps have the impeller spaced further away from the plate. Too much space between the impeller and the plate doesn't allow the water to be pumped through the engine properly. The water just cavitates at the water pump and doesn't get sent through the engine.
2. Defective thermostat (very common, just happened to me not long ago) If the thermostat is not opening all the way or not opening at all, the car will definetly overheat. It may also overheat if stuck open, but usually the indication is the heater will not blow out hot air.
3. Retarding the timing to stop engine knock and pinging.
4. Clogged water passages or radiator....common sense.
5. Defective fan clutch. (I've also had this problem)
6. Oversize pully/s which makes the water pump turn slower.
7. Missing radiator filler panel. (if applicable )
8. Missing raidator shroud.
9. Lose/worn belts.
10. Defective/wore out water pump.
11. Driving in Southern California during fire season!
Hope these tips may help someone out.