I have a 99 5.2 that needed a new water pump, the bearings were going bad and my fan had a lot if play in it. The truck has a 180 thermostat in it, and before the new water pump this thing stayed at 180, never moved at all. After the new pump which also came with the fan clutch, I bled all of the air out and now it’s overheating. I am keeping the cap off and it has so much pressure in it that it’s boiling and gushing out of the reservoir up to the sky a good 2 feet. Both rad hoses are too hot to touch, it will stay at 210 with the cap off but like I said, it will shoot out like a rocket. With the cap on it jumps up to 240 quick

im thinking I still have air in it, possibly pushing on the tstat and causing it not to open?

 

You still do have air in it. A tip I found through the forums is park on a hill with the front of the vehicle facing up the hill. Ramps or jack stands will work also. Also next time drill a little hole in the thermostat that will help!

 

i put it up on jack stands and still had no luck. Next I’ll drill two holes in the thermostat, there’s a crappy failsafe in there, should I just swap it out to a different one? It’s brand new though

 

Be sure to use a quality thermostat in addition to ensuring no air is still in the system. I use Stant Superstats and haven't had an issue with them to-date.

 

Drill one hole, and you sure you got the right temp thermostat?

 

Drilling that hole in the thermostat does get the air out of the block after changing that thing. If it still runs hot, there could be an issue with a blockage in the block coolant flow or the fan clutch could be shot.

 

just went out and put a new one it’s a 195. drilled the one hole and it’s holding at 210 but slowly climbs.

brand new fan clutch and water pump, don’t know what else it could be. Only thing is air in the system, but it seems to me that the pump isn’t working. My radiator is too hot to touch. The coolant in the radiator is steaming when i am waiting to burp the air out. This things holds its temp until I put the radiator cap back on. I’m stumped here.

 

Skip the safety stat. They suck. (and tend to fail rather quickly) Just get a stant thermostat, drill a hole in it, and call it a day.

 

Thats what I did, and still no luck!

 

Try burping it again. Radiator cap off, let the thermostat cycle a couple times. See what happens.