Mechanics

OVERHEATING

1994 Pontiac Grand Prix • 187,000 miles

My 1994 Grand Prix recently overheated. I removed the thermostat and tested it in boiling water. It was bad, so I replaced it. Now the temp guage reads between 150-225 while driving and moves toward the red when stopped. When you accellerate, it comes back down. The water pump looked fine. Is the sensor the likely culprit, or is there something else I need to check?
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Jay Davis
December 28, 2011.




Temp sensor may have been damaged located on rear of engine. Was coolant system air bleed?

Docfixit
Dec 28, 2011.
I bled the air according to the procedure in the Haynes manual. When I first started it, there was still air trapped in the heater core though, I could hear it gurgle.

Tiny
Jay Davis
Dec 28, 2011.
So opened bleeder valve till only coolant came out?

Docfixit
Dec 28, 2011.
That is right.
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Tiny
Jay Davis
Dec 28, 2011.
Can Ohm check temp sender @1k cold droping to @80 at 220. What temp is cooling fan coming on?

Docfixit
Dec 28, 2011.
I am not sure. Will have to check that.

Tiny
Jay Davis
Dec 28, 2011.
Maybe fan issue to check if it will operate turn AC on fan should come on to prove its operational

Docfixit
Dec 28, 2011.
To Ohm check the temp sensor, do I check resistance between the two terminals?

Tiny
Jay Davis
Dec 28, 2011.
Yes connector off

Docfixit
Dec 28, 2011.

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