50kta

i have a 2001 tahoe with a 5.3 and automatic tranny. the whole truck is stock.
the waterpump has ben replaced and the thermostat replaced also.
my problem is the truck runs hot, runs normal and overheats. basicly an intermitant overheating problem. sometimes it runs normal sometimes it runs about 230* sometimes it goes all the way up. i tried to make it overheat by putting it in drive with the air cond. on and rev it up to 2000 rpms for about 3 or so min......nothing but as soon as i put it in park and let off the throttle it went hot???
the rad is not clogged and the coolant is full all fluids are full. and the clutch fan has resistance.

50kta

just tried to burp the air out of the system with the heater onn and the cap off the expansion tank. and about five minuites into it the antifreeze started to boil out the expansion tank....i put the cap on and it over heated???

beingblueeyes

iTrader: (5)

have you tested the cap? or ran a cylinder leak down test yet?

Gadgetized

iTrader: (9)

Just a thought, before the water pump was replaced did you use a stop leak coolant additive? I really don't like that stuff unless it is a last resort like if you are broke down on the side of the road.

If you didn't use that stuff and just replaced the water pump, it must be a air bubble. I like squeezing the radiator hoses to get the air bubbles out.