2002 Venture heating up during uphill drives

2002 Venture, 3.4L, w/ 105,000 miles. Within the last 6 months, whenever I drive uphill for an extended period of time (for more than say 5 minutes), temperature increases. I have been able to keep it from reaching the red, but it’s been close. A few years ago I switched from Dex Cool to regular green ethylene glycol, and similar drives never gave me a problem w/temperature gauge.

This week I had the engine coolant flushed and filled, and wanted the shop to replace the thermostat. But shop told me a new thermostat for this vehicle costs $225 alone (not including labor), which I couldn’t believe. While I haven’t driven the vehicle on an uphill road that might increase the temp, I’m pretty sure the overheating problem is still there. Can anyone offer any suggestions why the vehicle has been recently heating on uphill drives? Could the cooling fan not be working (how to test for that?)? Also, how hard is it to change out the thermostat? I’ve changed out thermostats before on older vehicles (they usually cost about $25 or less in the past), and I figure that since I am using green antifreeze, I don’t have to worry about any special procedures for opening a coolant system that contains Dex Cool. Can anyone point me to a place that sells thermostats for a more reasonable price (other than $225)?

According to my info, thermostat is $10.00, gasket is $2.00. However, a thermostat housing is also listed, and it is an odd shaped piece. I’m thinking the thermostat housing is a bear to remove. Maybe the shop didn’t want to deal with it.

However, I think your chasing a red herring. When your climbing a hill, your asking more of the engine than regular cruising. This causes a heat build-up. Your problem is the cooling system is not able to evacuate that additional heat, and I’m thinking a partially clogged radiator. Flushing alone may not clear it. I had my radiator flow-tested at a radiator shop after a similar problem with my truck, and it was down to 40% capacity. Replaced it, and all was good. Just my 2 cents

The thermostat in this thing is a total PITA. My guess is that BustedKnuckles is right and the shop just doesn’t want to mess with it. I’d believe $225 in labor and say it probably isn’t bad. (My thermostat - the part - did run right in the neighborhood of $10-15 & came with a gasket).

As for the overheating, I’d say that BustedKnuckles has the most likely possibilities.