Heater blows cold air.

Tiny
THESAAMAN
  • MEMBER
  • 2001 BUICK CENTURY
  • 150,000 MILES
I just had the water pump replaced. Now the heater blows cold until the temperature gauge starts to climb to above normal. Suddenly it will start to blow hot and the temp will return to normal. However it still blows cold while idleing.
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Thursday, September 29th, 2011 AT 1:27 AM

5 Replies

Tiny
PROAUTOTECH
  • EXPERT
Best guess is thermostat which is an easy attempt at a fix.
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Thursday, September 29th, 2011 AT 1:43 AM
Tiny
WRENCHTECH
  • EXPERT
Sounds like you still have air in the system. They can be difficult to bleed and get totally full sometimes.
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Thursday, September 29th, 2011 AT 2:09 AM
Tiny
PROAUTOTECH
  • EXPERT
Good job wrenchtech, that's thinking outside of the box. I just assumed that was done already. But the fact that it does blow hot and then not, what do you think, just steam creating the heat? I agree though, not a bad thing to try. With a cold car and the radiator cap off and full of coolant, I would run the car until I saw the coolant drop, knowing that the thermostat did open. Add coolant as necessary, and its good to squeeze the hell out of all of the coolant hoses in order to burp out all the air. Be sure not to get burned or get caught in any belts or fan blades. Let me know how that goes.
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Thursday, September 29th, 2011 AT 2:19 AM
Tiny
WRENCHTECH
  • EXPERT
No, you can't run these engines with the cap off. They run too hot and will boil if not under pressure. From dead cold, fill the cooling system. Run the engine to operating temp and drive it one mile and then park it until COMPLETELY cold, fill again. Repeat this process until it doesn't take any more fluid.
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Thursday, September 29th, 2011 AT 2:24 AM
Tiny
PROAUTOTECH
  • EXPERT
Even until just after the thermostat opens to verify that it does? That one mile won't ensure that the stat opened, or that the fan engine temp triggered the fan. Burping the air out is the way I like to start, and then I do wrenchtech's way with the checking after short errands.
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Thursday, September 29th, 2011 AT 3:10 AM

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