heat goes down while driving - Maintenance and Repair Forum

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heat goes down while driving
Sunday, December 02, 2007 9:08 AM
i read the other article with the guy with the same problem and it didn't help me much.

its a 95 sunfire and it blows warm air while in neutral. not hot though. then when i take off it starts to get immediately cold. anti freeze is good so it sounds like the next thing to do would be the thermostat right? then a radiator flush? if that doesn't work what are the next steps after that?


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Re: heat goes down while driving
Sunday, December 02, 2007 9:11 AM
by the way how would a guy change the thermostat? i did a search but didn't come up with much


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Re: heat goes down while driving
Monday, December 03, 2007 12:16 PM
Certainly sounds like thermostat is not closing - failed or stuck open.

What year and engine if you want details on how to locate and change.
Re: heat goes down while driving
Monday, December 03, 2007 4:25 PM
its a 95 sunfire 2.2 L

I took a look under the hood and was unsure where it was. I've never had to change one of these before


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Re: heat goes down while driving
Wednesday, December 05, 2007 7:06 AM
-Drain coolant through rad drain (caution not to damage or break the plastic drain cock)
-Look for extension pipe on back of water pump (engine side)
-Do not undo bolts on extension tube at water pump
-Remove large hose from forward end of extension tube
-Remove 2 bolts securing hose adaptor from extension tube
-Remove hose adaptor (watch the thermostat captured within - not the way it is installed to make sure the new one goes in the same way.
-Clean old gasket material from extension tube and hose adaptor
-Put new thermostat in position, using new gasket and install 2 bolts through hose adaptor into extension tube.
-Tighten bolts to 125 inch pounds
-Reinstall hose and hose clamp
-Refill coolant
-Make sure to do coolant bleeding to get all the air out - from both the heater crossover tube and the bock out port to rad upper

Diagrams Here:
Diagrams
Re: heat goes down while driving
Wednesday, December 05, 2007 1:05 PM
buy a chiltons manual, it has a step by step


sounds like your thermostat is closed

I had this same problem several times when I still had an OHV under my hood









Re: heat goes down while driving
Friday, December 07, 2007 6:45 AM
wouldnt it be open?? if it was closed it wouldnt let the coolant out of the block.
Re: heat goes down while driving
Friday, December 07, 2007 7:02 AM
Yes- you are right - engine runs cold is T-Stat stuck or failed open (constant flow through the rad). Stuck or failed closed is bad - engine overheat (no flow through the rad).
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