little or no heat when stopped at light.

2007 Montana SV6 3.9. I have lots of heat when vehicle is reving 1500 -2000rpm. when idling at 700 little or no heat. recent flush, thermostat, and serpentine belt. I'm thinking, if it was the water pump not circulating enough water the car should be over heating. heat guage remains on the half mark.


any help appreciated. Gary

2007 Montana SV6 3.9. I have lots of heat when vehicle is reving 1500 -2000rpm. when idling at 700 little or no heat. recent flush, thermostat, and serpentine belt. I'm thinking, if it was the water pump not circulating enough water the car should be over heating. heat guage remains on the half mark.


any help appreciated. Gary


Did it heat ok before the flush, stat and belt? If so, I'd say there is air in the system.

had this problem before thermostat, flush and belt. Fluid level is never low. car in park it blows cool. mabey 90 to 100 degrees. step on gas and immediately 160 degrees. when I was changing the belt, I noticed the water pump pulley had absolutely no resistance when I spun it. is that normal ?

Have a look at this thread

http://chevroletforum.com/forum/uplander-31/2008-uplander-heat-problem-20931/

It has a lot of good information,

3 months later....I would hope the thread starter gives a feedback. The related thread seems to procure only a temporary solution in most cases...hinting the real problem is somewhere else and solved just for a time before it simply worsens.
And..a car water "pump" (rather a circulator) always feels as having no resistance.