C7Z51_2014

I'm looking for advice here, please.

C7 Z51

Radiator gauge hits 260 and drops back to 220 ten seconds later. I replaced the thermostat and it didn't help. I would like to ask if anyone has been through this before and if they identified the root cause?

Sorry, I should also add that this happens when I'm cruising at 60MPH and 65 degrees outside.

NSC5

Such rapid changes are generally from a sensor or wiring issue. Do you have a reader you can plug into the OBDII port to see the reported sensor value. The IP gauges are stepper motors and the display is probably damped. If you see huge instant changes in sensor reported value then the problem is almost certainly a sensor.

To actually get a 40 degree change in 10 seconds (I assume the rise is equally fast) would require temporary blockage/stoppage of coolant flow or a gas bubble at the sensor from HG or similar issues; either is a very low probability.

Is the car stock? If so it needs to go to the dealer for a check and to get this noted while in warranty.

js1977

What did the dealership say?

C7Z51_2014

HI:
Thank you for the reply.

Dealer suggested thermostat first before trying to hunt down a sensor. I like the dealer and find them very helpful. I'm taking it in next week but thought I would ask this group if anyone has already been down this road.

hawkgfr

I'd make sure it's been burped..

C7Z51_2014

Hmmm, I have 31K miles on it. Anything is possible tho.

hawkgfr

well probably not that then lol....


Could be a blown head gasket though...

ziominix

Hey sorry for the off topic reply, but how's the car doing with 31k? Any other issues you've experienced?

Thanks

C7Z51_2014

The car has been great, no issues.

Was thinking about the head gasket but there's no fluid anywhere and oil looks good. Also, there's no overheating on any of the other readouts.

Any other thoughts on what this could be are appreciated.

hawkgfr

Although I doubt it's likely I have owned a car one where the head gasket went bad and no leaks or noise...The only "tell' was bubbles in the coolant and it would stop after it warmed up...It did have a lot of condensation out the exhaust for a short period after a cold start but otherwise no signs of any problems except the rapid "hot then normal appearance of the gauge...The leak was small and allowed combustion into the coolant...



Your is probably a sensor or something else simple...good luck

C7Z51_2014

Ugh, I hope its simple.

NSC5

The dealer tech can easily test for exhaust gas contamination of the coolant but I still believe a sensor issue is much more likely than a HG issue. A defective coolant hose that collapses under suction is another very small possibility, not likely in a low mile vehicle however.

I recall reading about one new vehicle that had a piece of cooling system debris from a hose that was just large enough to get stuck from time to time in the thermostat passage, when it stuck the temperature would spike causing the thermostat to fully open allowing it to pass through and intermittently repeat. But the dealer should check for all the high likelihood stuff before looking for the "anything is possible" stuff in the tail of the probability curve.