overheating 2.7

[markoz]

I have an 2.7 intrepid 2001. For the past four years, I had no problems at all. About three months ago it started to overheat on the freeway. I pulled over and stopped, and accelerated it cool off to normal. I could continue for 10 – 15 miles on a hot day. And then again I had to stop and accelerate to 2500 rpm. The fans worked properly.

The vehicle has 135,000. Two weeks ago, the heads were rebuilt, new coolant temperature sensor, new water pump, new thermostat, new radiator, new cap, new radiator hoses, and new cheap water oulet . It happen again it overheated on the freeway. It blew off the cover of the water outlet. I bough a new water outlet from Dodge and installed it. I tried to bleed out the air. I had the valve open for continuos 10 minutes, and pressured air never stopped comming out, no coolant comes out. The coolant bottle was filled on maximum. It seems pressurized air is getting to the cooling system when the engine is running.

Any idea? Any help will be appreacciate? Thanks.

[Daytrepper]

About the only way the cooling system can be pressurized with air is a leak in the head gasket, allowing the cylinders to force air into the coolant passages -- if it happens with the engine cold or hot. With the engine hot, it could be steam pressure from the hot boiling coolant, if its just from the heat then coolant should still come out after the steam though.

You could be low on coolant, or the system wasnt filled properly when the heads were done creating air locks. Try filling the system with the engine off, and bleeder screw open. Do not close the screw until coolant comes out. This may take several minutes. Use a good 50/50 mix of water and antifreeze.

Its possible the head gasket was damaged during installation, or the heads werent checked for cracks or warpage properly.

[car5car]

It is possible to smell exhaust gas. To make it safe attach clear hose to bleeding screw. Another way to check for exhaust gas is to add special additive to coolant, but I never used it.