Relentlessly Overheating Pontiac Montana?

[eddy]

Hi Gang, Here are the symptoms, 2001 Pontiac Montana started overheating and while doing so the engine seemed to run rough and lose power.

I replaced the thermostat, the radiator, the A/C Condenser, I took the water pump out and brought it to a local auto parts store for inspection. They said is was fine.

Now I drive it and the thermostat pegs but it jumps around as does the gas gauge, I suspect a grounding issue. When I try to drain the air out of the bleed valves the one on the left, next to the water pump spits fluid quickly, the one on the right, next to the thermostat spits steam. When the engine is hot I turn on the interior heater but can't get any hot air in the cab, its all cold. I see no leaks of fluid anywhere. There is no oil in the radiator fluid or overflow tank and no smoke comes out of the exhaust so I don't believe there is a gasket issue.

Any suggestions, including pushing it off a cliff, is greatly appreciated. Sorry for the long winded question.

Eddy

 

[ianmcdca]

Did you ever find the solution?

 

[marducsworld]

This is what I did to my Chevy Venture. When I got it ,,,it ran hot always so,,,,,,,if it has dexcool,,,,,,and it looks clean,,,,change the little hose first on the top by the coolant bypass screw,then,,,,,get a bottle of Bars Liquid Aluminum and dump it in somehow,( I put it in the overflow because I cant get the radiator cap off,) Then ,make sure you have coolant. The Bars will fix the problems if the heater core is good. Make sure you bleed the 2 screws and get the air out of the system best you can even if you have to park up a ramp to get the air out. Let it run with the heater on High for an hour and see if if runs cooler. Dont worry about what anyone says about putting stop leak in these vans,,,the are a pos anyway so whats the harm? If they did this at the factory,,,they would not have so many problems because of stupid engineering.
Even better ,,,if you can,,,put in the Yellow coolant if you dont have the dexcool crap already in there but ,,,the Bars will work good with the Dexcool if is not already turned brown.