2017 Sierra Denali Coolant Leak 5.3L V8

[Claudio Hoch]

Today I noticed my temp gauge hit 260 which freaked me the F++K out because its never happended before.  Lately the cooling fan has been staying on when I shut the truck off but I just figured ANOTHER issue(i have a ton with the truck)  So I opend hood, check for coolant leaks and seems coolant is leaking from overflow tank or heater hose.  Removed bottle and looked for cracks which I found NONE.  The hose also seems to be normal with no bubbles tears or anything remotely weird.  Has anyone else experienced this?  Can it be something major  Truck has been running perfect until today.  Anyone?

[CamGTP]

The thermostat could not be working correctly and sent the coolant temp sky high causing super high pressure and a possible leak.

 

Only guessing here. I'd pressure test the cooling system to test for leaks. If you don't have one of these tools, you may need to bring it somewhere or rent one. If no leaks are found, then you could be looking at a different issue like a thermostat.

[HeySkippyDog]

Bad water pump?

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