1987 Pontiac Firebird Only overheats when speeding?

1987 PONTIAC FIREBIRD
11,200 MILES • V8 • 2WD • AUTOMATIC
Avatar
MRDENNIS87
  • MEMBER
  • 2 POSTS
hi, i've been noticing if I go over 55-60 mph and or race it a lil bit either one.. it will start to overheat and quickly.. ia m assuming it is because of the air deflector being broke on bottom ? an it also losses coolant, no smoek out exhaust, non in oil... im guessing coolant is form whe nit over heats ? ( has never overheated moking out of hood o rnething ust gets sooo hot n vaporlocks..
Jan 12, 2010 at 3:57 PM
Advertisement
Avatar
ERNEST CLARK
  • CAR REPAIR CONTRIBUTOR
  • 1,730 POSTS
Sounds like a bad water pump, stuck thermostat or air/debris in the system.

First, while the engine is cold, pop the radiator cap or surge tank cap. Bring your engine to normal operating temp. (When your fans come on, it's at temp) Then feel the upper and lower radiator hoses. If both are warm, then you know the thermostat is opening. If one is hot, the other not, then the thermostat is stuck closed.

If the thermostat is opening, and before your engine gets too hot, check for the water pump operation/clogged radiator or heater core by reving your engine and watching the coolant for a rise in the radiator or surge tank. (That's easy to verify)

If you don't get a rise, then either the water pump is bad or you have something clogging your system. You'll have to perform a coolant flush and/or replace the pump.
Jan 20, 2010 at 10:30 AM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.