Thanks. Ran it with the front heat on 90 degrees but rear zone on medium. The vehicle was not lifted in the nose. Guess I will try again this weekend.smj999smj wrote:I doubt that it's the water pump. If it was, it would overheat. Also, the VQ water pumps seldom fail and impeller fan corrosion is almost non-existent these days of long-life coolants (assuming somebody doesn't drain the coolant and re-fill with straight water! You said you burped the coolant, but did you do it the way I often recommend?
First, make sure the radiator cap and reservoir caps are in the right place; the reservoir cap has the spring on the bottom and the radiator cap does not. Make sure the coolant is topped off. Coolant in the reservoir should be at least the MAX FILL line. Jack the vehicle up as safely as possible, or drive up on a set of ramps or park on a steep uphill...to get the nose of the vehicle higher up than the tail. Start the engine and set the front and rear heaters to the maximum hot settings. Run the engine at 2000-3000 RPM for at least 10 minutes or until hot air comes out of the heater vents. If you have a thermometer, normal heat output is about 140 degrees F. Once you get heat out of the vents, you can shut the engine off and lower it, if needed. Re-check the coolant level again when the engine is cold. This usually works 95% of the time, assuming the thermostat isn't stuck open. If you've noticed the coolant gauge needle is sitting near the cold side of the gauge while driving, then I would suggest replacing the thermostat. Typically the needle will sit right in the center of the gauge.
Try the purge method I described and see if it fixes it. If it doesn't, it may be the heater pump that is faulty.underworld1001 wrote:I have poor heater performance when the vehicle is idling as well. I've been reading up on this and have a hunch it could be the auxiliary water pump that's going bad. Not sure what the consensus would be on that. SMJ?