2008 Colorado, 5 cyl, 176k miles, bought used in 2017. I learned early on that the truck overheats above the middle point and up to the ¾ mark on the temp gauge when it’s hot outside and if I run the AC. I recently took the truck to a mechanic to have a few things done and I asked if they would look into that. They said they couldn’t find anything wrong. I asked them to replace the thermostat just to see if that had an effect. It did. The truck now overheats above the mid-way mark whether I do or don’t run the AC. Excessive strain on the truck like an extended, uphill, 55-65 mph drive causes the temp to go up more, as does running the AC, still.
I did a flush this morning and poured in a quart of Blue Devil radiator flush, oil degreaser & rust remover, topped off with water, and ran the engine for well over a half hour, even driving to Napa and back. My father-in-law had commandeered the operation and mentioned that he wasn’t sure how much coolant came out when he initially disconnected the lower radiator hose (he just let it spill all over my driveway) nor how much water he had to add to fill it back up after adding the system flush.
I caught the next flush in a pan. We disconnected the hose at the bottom, left the cap off, ran the truck with the heater on until the engine temp climbed just above the mid-point on the gauge which should have been sufficient to open up the thermostat and allow any remaining coolant to drain out.
I measured the herbal tea-colored water with small bits of crud in it that had collected in the pan and it was 3 liters plus about one cup. We filled the radiator back up and performed the same procedure. I didn’t drive the truck around the block this time. We just kept it in park and ran it at 2k RPM until the engine warmed above half-way again. That time I got just over 4 liters of more herbal tea-colored water with small bits of crud in it when we drained the system. I allowed it to drain longer that time, until it had basically stopped dripping out.
The manual says the truck is supposed to hold 10 liters of coolant. If I’m only getting 4 when it drains, where’s the other 6? Seems an excessive amount to get left behind. Also, when the truck was running, the hose at the top of the radiator felt hot and the one at the bottom felt cold, according to my father-in-law. He also reported that he thought the water that drained out should have been hotter given the temp displayed in the gauge when we were running the engine.
Someone mentioned I should make sure the fins in front of the radiator are clean. I looked at them with a flashlight and there’s a bug here and there but it doesn’t look clogged. Still, I’m going to the carwash to blast it as best I can with the pressure wand.
Was the new thermostat bad out of the box? Is it the water pump? Is it the radiator itself that needs replacing? Is there an obstruction somewhere in the line? Any insight is appreciated. Thanks
I did a flush this morning and poured in a quart of Blue Devil radiator flush, oil degreaser & rust remover, topped off with water, and ran the engine for well over a half hour, even driving to Napa and back. My father-in-law had commandeered the operation and mentioned that he wasn’t sure how much coolant came out when he initially disconnected the lower radiator hose (he just let it spill all over my driveway) nor how much water he had to add to fill it back up after adding the system flush.
I caught the next flush in a pan. We disconnected the hose at the bottom, left the cap off, ran the truck with the heater on until the engine temp climbed just above the mid-point on the gauge which should have been sufficient to open up the thermostat and allow any remaining coolant to drain out.
I measured the herbal tea-colored water with small bits of crud in it that had collected in the pan and it was 3 liters plus about one cup. We filled the radiator back up and performed the same procedure. I didn’t drive the truck around the block this time. We just kept it in park and ran it at 2k RPM until the engine warmed above half-way again. That time I got just over 4 liters of more herbal tea-colored water with small bits of crud in it when we drained the system. I allowed it to drain longer that time, until it had basically stopped dripping out.
The manual says the truck is supposed to hold 10 liters of coolant. If I’m only getting 4 when it drains, where’s the other 6? Seems an excessive amount to get left behind. Also, when the truck was running, the hose at the top of the radiator felt hot and the one at the bottom felt cold, according to my father-in-law. He also reported that he thought the water that drained out should have been hotter given the temp displayed in the gauge when we were running the engine.
Someone mentioned I should make sure the fins in front of the radiator are clean. I looked at them with a flashlight and there’s a bug here and there but it doesn’t look clogged. Still, I’m going to the carwash to blast it as best I can with the pressure wand.
Was the new thermostat bad out of the box? Is it the water pump? Is it the radiator itself that needs replacing? Is there an obstruction somewhere in the line? Any insight is appreciated. Thanks
