Thermostat needle rises when idle but lowers when driving

Drami5 · Jan 22, 2015

I recently noticed when i'm at a stop sign, the thermostat needle starts rising slowly to the H. I then went back home and noticed that when I drive the needle is normal.. it's only when im idling when the needle rises.

I also checked my oil, antifreeze, and everything is great.

Any ideas on what it could be?

DarkSideAccord · Jan 22, 2015

check if your fans work.... when moving, the air is cooling down the motor. At idle, no air flows through

xci.ed6 · Jan 22, 2015

first easy check /\

but 'at idle' may not mean enough, hold throttle at 3krpm, in neutral, not moving, watch gauges

Drami5 · Jan 22, 2015

DarkSideAccord said:
check if your fans work.... when moving, the air is cooling down the motor. At idle, no air flows through

Yeah fans work

xci.ed6 said:
first easy check /\

but 'at idle' may not mean enough, hold throttle at 3krpm, in neutral, not moving, watch gauges

It just stays the same , 3/4 to the H

xci.ed6 · Jan 22, 2015

Ok, sounds like a 'flow' issue, make sure the radiator IS NOT BLOCKED (road trash / etc...).

Try a thermostat, if it's open to air.

After, if it still happens, your thinkin internal block (common if stop-leak used) or pump has no blades (common on some w/ plastic impeller).

Drami5 · Jan 22, 2015

xci.ed6 said:
Ok, sounds like a 'flow' issue, make sure the radiator IS NOT BLOCKED (road trash / etc...).

Try a thermostat, if it's open to air.

After, if it still happens, your thinkin internal block (common if stop-leak used) or pump has no blades (common on some w/ plastic impeller).

I'm gonna have it checked out to see what it is..

thanks xci you're everywhere to help haha

xci.ed6 · Jan 22, 2015

oh, was made assuming coolant tank full, and radiator (check cold) cause a busted cap will empty rad, to res, so it looks full there.

Start when cold, check rad for any 'bubble' action

goldenchamp · Feb 5, 2015

I had an old CB7 that did this after some major engine work. It turned out that the thermostat was stuck. Replacing that seemed to cure it, and it was innocuous enough. Maybe give that a try if nothing that was previously said worked?