[RESOLVED] Changed Thermostat, Now no heat at idle

[MaxPSITalon]

My car overheated over the summer. I changed the thermostat and and everything was back to normal. Now that it is getting cold out here in Michigan, i have noticed that at an idle my heat blows cold, but when cruising over 2500 RPM the heat is hot as can be. But once i stop at a stoplight its cold again.

After doing several searches I think there could be an air pocket in the system (after changing thermostat), but i also read that DSMs don't get air pockets.

Has anyone else had this issue? I am tired of freezing at every light every morning. What should i do? Thanks in advance!!

 

[stevew1]

Did you burp the system of air when you refilled your coolant after changing the t stat?

 

[MaxPSITalon]

no, i read somewhere that you dont have to do that. I guess that is my question... do i need to burp the system? or is the new (well newer it was 5 months ago) thermostat faulty?

Has anyone else experienced this? If so, was it resolved and how?

 

[99RedGs]

It will burp itself with normal driving. Just make sure you have coolant in your overflow.

 

[MaxPSITalon]

It will burp itself with normal driving. Just make sure you have coolant in your overflow.

Are you saying I should add coolant to the overflow? I don't see ow that would help. Do you mean is the radiator full?

I need to buy some antifreeze tomorrow and i will top off the radiator. I know i filled it when i changed the thermostat... but it might be low.

Would being low on coolant cause this?

 

[Jeff99GS]

Sounds stupid but did you put the T-stat in backwards?

 

[MaxPSITalon]

I dont think so... it has been like 5 or 6 months and i would have probably noticed a problem.... like overheating. And it has heat when i am over 2500 RPMs, so the thermostat is opening.

 

[PIMking]

Are you losing coolant? is the passenger floor wet?

 

[MaxPSITalon]

no coolant loss, no problems never gets hot. Just the darn heat blows cold at an idle. I am going to add coolant tomorrow, but i doubt that it is low. no the passenger floor is not wet

 

[PIMking]

What temp is your thermostat?

 

[MaxPSITalon]

I got it from Autozone 180 degree. I believe that is the OEM temperature

 

[Defiant]

Should be a 190, but the most likely problem is that it's not fully closing. Check, and replace if needed. Also check your heater control pushrods, and the heat control door and make sure it's moving freely. DSMs have no hot water valve, they only direct the air either through or around the heater core, fairly common Detroit design.

The cooling system on a DSM will have evacuated its air by the third time it's been heated and cooled. It has no unusual high points to trap any.

 

[e39a]

i suggest you get a thermostat from the dealer. I had problems with the ones from autozone

 

[MaxPSITalon]

I added coolant.... about 1/4 gallon and the problem is solved.

I must not have filled it completely after draining it to change the t-stat.
I figured i should post what i did to resolve the problem to help others in the future. Thanks for all the input