Evening everyone, I picked up a 2000 olds silhouette the not to distant cousin of the venture with the 3.4L the other day for a $1000 guy said they replaced the radiator, water pump and hoses and that is still was over heating. I bought thinking that i would be doing lower intake gaskets on it. After i got it home i checked the oil and there is no milky color and no condensation on the oil fill cap. the coolant is a nice orange color. i then hooked my coolant pressure tester up to it and pumped it up to 16 psi and it held rock steady for over an hour. i then topped off the radiator and opened up the bleeders and waited for the coolant to start to trickle out of them. I tightened them up, put on the rad cap, fired up the van and worked the bleeders back and forth untill i got a steady stream out of both. turned on the heat and had nice hot air blowing out. jumped in the van and went for a drive. got stuck in rush hour traffic jam and temp gauge stayed below half got on the freeway and opened it up and gauge stayed below half way. after driving the van for more than an hour in both stop and go and freeway traffic and the gauge never going over half i figured i was good. stopped at a friends house left about an hour later got about 2 miles down the road and the temp gauge pegged out. pulled over and the van had pushed the coolant from the radiator to the over flow and had now allowed it to come back into the radiator drained the coolant over flow into the radiator re-bled the system and van was fine again untill i stopped for over an hour. then the same thing happened again. Any ideas of what can be causing this?

 

I would suspect a head gasket issue, I have done many 3.4 head gasket repairs.

When it boils out does the coolant smell like exhaust fumes? There are test kits available to check for this.