temperature fluctuates

[stormn]

Hi. I'm new to the forum. I have a coolant temp. problem with my 93 Yukon. A few weeks ago I noticed the temp gauge running about 65c, it normally ran at 95c, & was slow to warm up. Had the thermostat changed and the temp started to fluctuate from 65c to 95c. A infrared temp. gun confirmed this. My mech. changed it again, no charge, and said if it was still the same, they'd have to look for something else.It's still the same. The gauge used to run at a steady 95c all the time. Is he using the wrong t'stat?

 

[jwpotts0413]

first check the heater valve, then the water pump. those are cheap and relatively easy to change. heater valve is $13 water pump is $40. if that aint it look at the top of yer motor and look for fluid leaking around the intake manifold where it meets the heads/block. if u see fluid there u need a new intake gasket ($60 part + $400 labor). i roasted mine and u could put hose into the radiator with the truck running and see all the fluid leaking out the back of the motor onto the ground under the truck. it sucked, i paid midas to fix it and didn't have my hoe for 3 days

 

[stormn]

No fluid leaks . Heater valve works o.k. Water pump has only 24,000 mi. Is there a right or wrong brand of t'stat?

 

[JKmotorsports]

Temp fluctuation can sometimes be caused by a cavity in the coolant caused by an air pocket. Remove the radiator cap while the eng is cold, turn on the heater, start the engine and let the fluid recirculate with the cap off for a minute or so. While it is running, top off the radiator with coolant then re-install the cap and see if that helps.
Also, while you have the cap off while the engine is still cold, check the coolant circulation and make sure there is a steady flow. If not, your pump could be failing or you could have deposits or buildup in your radiator, pump, or intake/head/block water passages.

 

[jwpotts0413]

as far as i kno a t'stat is a t'stat. i use a 160 b/c i have a hypertech hyperpack but stock is 180 or 185 degree i think. good info from JK he knows his sh!t