Yeah, if the fans cannot bring the temps down low enough to shut themselves off, then that suggests the system isn't cooling enough to turn the fans off, which in turn suggests a reduction in cooling capacity. That, of course, assumes the fan system is operating as designed -- high speed, low speed, at designated set points, etc. -- lots of subtle problems can trick you there. That 'could' be paper towel sludge in the radiator, but could also be traditional cooling system issues. They should be able to test the radiator for restrictions, since that would likely be the most vulnerable place for paper towel sludge to impair cooling capacity.River19 wrote: Wed Apr 29, 2026 2:22 am Thanks @Tom
They replaced the thermo switch and said the fans are coming on but they wouldn't shut off suggesting there may have been some gunk/crap/towel causing some inconsistent activity.
They are going to flush and bleed the cooling system again today for giggles to see if they can get anything else out.
For my own future reference........if the car was truly running hot and nearing "overheating" what temps would I see at the block and heat sensor location with the IR temp gun? (planning ahead for monitoring)
As for the IR gun, I'm not a big fan of using that to confirm the gauge -- too many variables in play to get reliable results. Did they not confirm the accuracy of the gauge? It's an easy two part test -- first confirm the sender is creating the right reading for a given/known temperature, then confirm the gauge is showing the right temp for a given/know resistance value.
You can find a detailed guide for testing the sender here. And you can get the specifics on confirming the gauges accuracy with a cheap resistor or two in this post. If you were interested in testing I can help walk you through it.
It would be good to take that off the table, but if the temp gauge shows a 'normal' reading (half way or less) while cruising the highway and heats up in stop and go traffic -- that would strongly suggest it's directionally accurate -- at least accurate enough to treat indicated overheating as a real issue.