temps rise, then fall

[99tahoeinwv]

ok, finally got misfire fixed. another issue im having is the temps. last fall i replaced the thermostat because i caught the temps rising and then falling down to operating temps. havent driven it much over the winter since i was having misfire codes. drove it this weekend and the temps will rise almost to redline and then drops to normal operating temp. and it stays at normal level the rest of the trip. its only after initial start up. any thoughts would be appreciated. last night i started it and took radiator cap off and started it and let it run, system seemed to burp several different bubbles of air, but temps went just above 210 and dropped down to normal. im at a loss.

 

[TnTahoe]

Check for air in your coolant system.

 

[99tahoeinwv]

tnt, besides running with cap off and letting it burp, whats the best way to do that? thanks.

 

[TnTahoe]

Some vehicles actually have bleeder screws on them, but other than that just try the way you mentioned. Some other methods here: http://www.tahoeyukonforum.com/forum/showthread.php?t=22021

 

[99tahoeinwv]

ok, where would the bleeder be? on top somewhere i would imagine?

 

[TnTahoe]

Yeah I have seen some on the thermostat housing, im not sure there is one on your vehicle or not tho.

 

[SunlitComet]

that or a defective thermostat.

 

[retorq]

If it's getting up to redline and coming back down you could have a massive clog somewhere ... bypass or one of the head passages, get your hands on one of them infared guns and get temps that way ...

 

[YUKON1999]

x2 the thermostat mine did that too

 

[99tahoeinwv]

Would a thermostat have gone bad that quick? Ill start with that and see