Chevy techs, please put your thinking cap on.

[63corvette]

Originally Posted by 7423

I have a 1998 1/2 ton GMC Savana with a 5.7 vortec.. At 120,000 miles, the intake gaskets leaked water. After changing the gaskets, the leak is gone but the motor will not get to normal operating temperature. We have changed the thermostate 3 times with the correct style 190. degree for the vortec. The oe temp gauge climbs to 200 degrees, the thermostate opens and it drops to 140 degrees. It will do this all day long. I have cardboard in front of the radiator. The radiator hoses never get over 170 degrees there fore the heater never works. The heater control valve works properly with a vacuum pump attached. I live in SoCal where most days are warm. Any thoughts??

My 1996 Chevy has done the exact same thing since I bought it new in March 1996.
Mine has the towing package and engine oil cooler also.
I questioned GM about it and was told that was normal until the engine has a load to pull and work the engine and cooling system.
I have 104,000 miles and still going strong.
On a hot day in TX it will stay constant about 190 on the gauge but when it is cool it is up an down on the gauge from about 140 to 190. I have not ever checked the heater temp but it seems to warm the cabin ok even when it is really cold.
It is just working the thermostat.
My Experience
Rick Cates