1994 GMC Van heater cold

1994 GMC VAN
Avatar
PEENPEEN50
  • MEMBER
  • 2 POSTS
Heater problem
1994 GMC Van V8 Two Wheel Drive 136000 miles

put in new thermostat and heater core still cold mechanic said new thermo prob defective is this right
Jan 14, 2009 at 10:23 PM
Advertisement
Avatar
JDL
  • CERTIFIED EXPERT
  • 16,098 POSTS
Does the engine reach normal operating temp, according to the temp gage on the dash?

With a warmed up engine idling and the heater turned on, can you feel of the heater hoses under the hood, are they both hot?

Sometimes I check for coolant flow through the radiator, by removing the cap on a cold engine. I have drained the coolant down so I could see the top two or three coolant passages in a cross-flow radiator. Start the vehicle, if I see coolant flow instantly through the passages, something is wrong, I check the thermostat. If your radiator has a tall neck where the cap goes, you may not be able to see those passages. It was just a thought.
Jan 14, 2009 at 11:04 PM