Weird overheating

gmc
suburban

#1

I have a new 180 degree t-stat, but my truck pegs out the gauge and fills the reservoir then cools off.Sometimes twice. Then runs about 160 degrees. Tried 2 t-stats, then splurged for an expensive one. Still happening. 16 lb. radiator cap. Pretty sure it’s not the fan clutch, the fan turns all the time.


#2

Air bubble


#3

What’s the procedure for burping the system?

On my motorcycle, you just let it warm up and pop the throttle a couple times. Then you let it cool down, remove the radiator cap, and top it off. Repeat as necessary.

Would the procedure be the same for a Suburban?


#4

I believe that was it. I loosened top hose and stuck a screw driver in between hose and radiator inlet and let it run. tightened hose up and drove it some and the gauge didn’t peg out before it cooled down.I’ll drive it some more tonight and see what happens. Think that did it. We’ll see. Thanks for the sage advice.


#5

if you have an injected suburban, that t-stat is not hot enough. should be 195. running cooler will give you worse fuel economy.


#6

On many engines it is very convenient to install the ‘T’ made for flushing cooling systems. The ‘T’ has an air tight threaded cap that makes it easy to open and allow air to escape. When installed in the heater hose that exits the intake, midway to the firewall, the hose can be held up above the level of the heater core where all the air will accumulate. If a regulated air pressure source is available, introducing 5 psi at the overflow connection on the radiator and then loosening the flush cap and lifting the hose will make for a safe and convenient burp. I would suggest that the thermostat be inspected and if there is no bleed hole on the thermostat’s base ring drill one, using the smallest bit available.