Chevrolet Repair: Chevy Venture Van, chevy venture van, chevy venture

Question
Hi,
I have a 99 Chevy Venture van with approx 80k miles.  Antifreeze was leaking from the engine and the temp gauge slowly increased in temperature to about 3/4 of the way up on the gauge after several miles of winter travel, then quickly dropped off to below normal operating temperature.  The heater also failed to warm up the inside of the van as well.  

I replaced the thermostat and water pump hoping to solve these problems.  The leak is fixed, but the van still fails to heat the interior properly and the gauge still bounces from below normal to 3/4 of the way on the gauge, in a continuous cycle of 45 seconds to a minute.  

The belt is not slipping but I do not know what is causing my problem.  Any help is appreciated.  

Thanks,

Brad


Answer
Sounds like air in the cooling system.
The temp sender needs to be in contact with coolant to work. So does the thermostat.
You may want to loosen the thermostat bolts, and bleed the air out.
Actually, remove the thermostat, and make sure it is installed in the correct direction while you are at it.

Van