Coming home from out in the hills, my 2022 PW with 85K miles overheated after ~20 minutes of easy driving (mostly downhill, cool evening, 70 mph on interstate when it threw the overheat). Pulled up gauges to watch the oil and water temp, ~235F and 250F respectively. Pulled over at the first exit. At idle the temp continued to climb, so I shut it off, let it cool down, then limped home ~10 miles with heater at full blast blowing hot air - luckily it was a cool evening and I drove with windows open.
Eventually diagnosed it as a thermostat stuck shut. Searching forums I couldn't find this failure very well described, so I hope this helps someone. A few things observed, and narrowed down the problem.
- Using a flashlight, verified that both fans were running (it is hard to see the electric one, but it definitely turns on at ~230F).
- No coolant leaks, in particular checked the water pump. Coolant level in reservoir was normal.
- From cold, it heats up to 230F within ~10 minutes but the top radiator hose stays cool to the touch and verified at ambient with an IR thermometer. That was the dead giveaway for a thermostat stuck closed.
Note that in these trucks the heater core supply line is *before* the thermostat, so blasting the heat helped keep the engine cool enough to limp home.
FWIW Autozone thermostat is exactly the same as the OEM. Box was rebranded, but the actual units are identical including markings.
I searched and didn't ever find a bleed port. Luckily a friend has Airlift coolant pressure/bleed system, that was a lifesaver!
Cost me a Saturday afternoon and a few beers, but it is back up and running normally! While I was in there I replaced the air filter, EGR valve and cleaned the MAF sensor.
Eventually diagnosed it as a thermostat stuck shut. Searching forums I couldn't find this failure very well described, so I hope this helps someone. A few things observed, and narrowed down the problem.
- Using a flashlight, verified that both fans were running (it is hard to see the electric one, but it definitely turns on at ~230F).
- No coolant leaks, in particular checked the water pump. Coolant level in reservoir was normal.
- From cold, it heats up to 230F within ~10 minutes but the top radiator hose stays cool to the touch and verified at ambient with an IR thermometer. That was the dead giveaway for a thermostat stuck closed.
Note that in these trucks the heater core supply line is *before* the thermostat, so blasting the heat helped keep the engine cool enough to limp home.
FWIW Autozone thermostat is exactly the same as the OEM. Box was rebranded, but the actual units are identical including markings.
I searched and didn't ever find a bleed port. Luckily a friend has Airlift coolant pressure/bleed system, that was a lifesaver!
Cost me a Saturday afternoon and a few beers, but it is back up and running normally! While I was in there I replaced the air filter, EGR valve and cleaned the MAF sensor.
