bogator1

Ok,

Radiator good no restrictions, Fans both come on when hot. Coolant -Flushed no sludge no leaks, no oil or fuel in coolant no water in oil, so headgasket ck ok. new thermostat old one was good too. no air in system blead air per the book. when sitting in my driveway it will run for 1 1/2 hours fine cycling the fans to keep the temp normal, but aftre driving for 20 min the temp pegs out. my mechanic says everything is fine because it is when it sits in his shop idling. I have a cool air intake but thats it for mods, Any help

Matta1

Bad waterpump perhaps?
Low oil or coolant level?
Does it only overheat when the AC is on?
How do you drive it? High rpm's all the time or low to medium rpm's?
Something could cause major friction in the engine which makes it overheat?

Just throwing out some thoughts...

el_baby

about the leaks... after you run (when it gets hot) you need to add water? it only happens when you are running? or it hd happend in the garage?

to check the waterpump... when the engine is cold, open the radiator cap and start the car... i beleive the first change of water is when the fans starts...

keep looking and you should see the water flowing... and if you accel the car it will flow more (duh!) that may come out of the rad..

dont know if its the correct way to check the waterpump... but give it a try

String1015

Check for coolant flow. Check heater core for a clog too. I hooked up a garden hose to the heater core and slowly turned it on. I went through the same problem. My water pump fins rusted off and one got stuck in the block. One way to check is pull off upper rad hose n also your lower rad hose should be cold and upper rad is hot. I then dealt with building of pressure in my motor and coolant would steam out the overflow tank.