'91 sierra temp fluctuation

steeldawg · 01-15-2009, 05:04 PM

Recently my temp guage has been fluctuating from nornal operating temp to pegging in the red.It will peg out and suddenly drop to normal suddenly and consistantly.My first instinct was the thermostat.Replace it, but problem persists.Any help?

bradrhale · 01-15-2009, 05:49 PM

air in the system is a good possibility. remove the cap while cold and let it warm up. watch for bubbles. remember too that just because you bought a new part, that part can be defective also. doubtful, but it does happen. i would check into burping the system first.

leolkfrm · 01-15-2009, 06:54 PM

I agree with brad, and i would also check the wire to the temp switch for the guage for any rub point to ground

01-15-2009, 05:04 PM	#1
steeldawg Junior Member Join Date: Sep 2008 Posts: 3	'91 sierra temp fluctuation Recently my temp guage has been fluctuating from nornal operating temp to pegging in the red.It will peg out and suddenly drop to normal suddenly and consistantly.My first instinct was the thermostat.Replace it, but problem persists.Any help?

01-15-2009, 06:54 PM	#3
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,300	I agree with brad, and i would also check the wire to the temp switch for the guage for any rub point to ground __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

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01-15-2009, 05:49 PM	#2
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,025	air in the system is a good possibility. remove the cap while cold and let it warm up. watch for bubbles. remember too that just because you bought a new part, that part can be defective also. doubtful, but it does happen. i would check into burping the system first.