Can you cook a thermostat?

[Fox8950]

I recently overheated my car a little much when I had a air bubble in the system and ever since then the temp needle has to spike before the thermostat opens and the temp drops back down to mid range where its supposed to be. This always happen when you get em to hot? Was changing it today anyhow while I was in there just curious.

 

[5spd GT]

First, make sure you have enough coolant in the radiator

 

[HISSIN50]

What you describe could be normal depending upon how far the needle goes. What numeric temp are you seeing?

Air bubbles, especially at high RPM, can really hose up a t-stat. The sloshing against the pellet can wipe out its calibration (esp for non-balanced stats).

 

[corvetteguy]

I have never seen a thermostat that
did not spike on initial warm up.
Whatever spike it is I have never
seen a idiot light warn about overheating.

 

[5spd GT]

My 4.6L does not spike according to the guage.

 

[LiquidGT]

My gauge used to be normal, then a couple of years ago it started to spike on itnital warm up.

 

[irish]

Sure add a little salt/pepper but they are kinda crunchy....seriously though if I have the slightest doubt about the T-stat I replace it with a good quality unit as they are very cheap and not hard to change.

Matt

 

[Fox8950]

Well the new one works fine and doesn't spike my temp before it drops (when I said spike it would kick the needle all the way up top to 270 deg) it either got hosed from the heat or the sloshing when I had the air bubble from refilling or from the initial upper rad hose blowout that started the whole thing

 

[HISSIN50]

The t-stat should never allow a 'spike'.

In newer cars you can see quite a lag (and increase in temps) before the E-fan kicks on, but that's all I can think of. A spike before the stat opens would not be considered normal in my book.