2003 Pontiac grang prix overheating.

Tiny
RLRIPPY1980
  • MEMBER
  • 2003 PONTIAC GRAND PRIX
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 1,250,000 MILES
I have a 2003 pontiac grand prix. It started overheating a few weeks ago. Replaced the head and intake gaskits. Ran fine for a day or two. Began running hot again. Replaced thermostat, No change. Replaced water pump. No change. Flushed radiator. No change. Will idle cool, but when you press gas or try to drive it instantly begins to heat up. Heater does not get hot even after new thermostat.
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Wednesday, March 30th, 2011 AT 4:07 PM

5 Replies

Tiny
JDL
  • EXPERT
Does the radiator fan work? What is the temp gage reading? Is there any coolant flow?
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Wednesday, March 30th, 2011 AT 6:18 PM
Tiny
RLRIPPY1980
  • MEMBER
Yes the fan is working. The temp gauge reads cool until you rev engine or drive, then it jumps almost to red instantly. We kill it before it reaches red. Not sure of coolant flow. Motor seems to be hot while radiator and cap stay cool.
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Wednesday, March 30th, 2011 AT 6:28 PM
Tiny
JDL
  • EXPERT
What is engine litre size? Low speed fan comes on about 220F. Highspeed fan comes on about 230F. Hot coolant lite comes on about 260F.

Does your system use radiator cap? Can you see coolant with cap removed? Does the reservoir fill up in a hurry? Too hot is a boil over. Maybe your gage isn't reading correctly? Your radiator hoses don't get hot?

One way to check for coolant flow, is too remove the thermostat. Hook everything back up, just for testing, remove the cap, can you see or feel coolant flow?
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Wednesday, March 30th, 2011 AT 7:22 PM
Tiny
RLRIPPY1980
  • MEMBER
The engine is a 3100, 6 cylinder. The fans kick on but don't seem to help much. Once it starts getting hot all you can do is kill the engine. Have not tried to drive. It does have a radiator cap. I can see water in radiator. And no the hose on the radiator does not get hot. Niether does cap. Just the motor. LIke there is no coolant or water flow. Will try what you suggested, maybe we bought a bad thermostat. Could it be a sensor, aking it run hot.
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Wednesday, March 30th, 2011 AT 7:48 PM
Tiny
JDL
  • EXPERT
If you don't have any flow, check the water pump.
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Wednesday, March 30th, 2011 AT 8:00 PM

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