I have a 1988 1500 with the 4.3 V-6. After Im running it a bit and it warms the temp gauge will go all the way to the top then when I stop and shut it off I can hear the coolant in the overfloew glugging. Then when I re start it a minute later the temp gauge usually always goes back down. I first thought it was just my gauge because the oil pressure gague always moves around and drops when the truck warms up but there is oil in it. But the glugging around in the overflow when I stop means something isent right. Anyone had this happen?

It might have air trapped in the system. Do you still have a factory rad cap on it? If so throw it away buy a Stant and burp your system to get the air out. If this don't help your t-stat might be sticking.

If it is the T-Stat sticking will I have to get a whole new one?

If it is the T-Stat sticking will I have to get a whole new one?

Yes. They are not serviceable.

//2000CAYukon