Stumped with high temp gauge reading...

I have an LS3 with an Entropy radiator in my 68 Camaro. When I bring the car up to temp the gauge keeps steadily climbing to almost 250 degrees however when I use my infrared temp gun on the upper hose it reads approx 150 degrees and the lower hose is right around 110 degrees. I replaced the thermostat this morning hoping it was that but its still doing it.

What's weird is I've cruised it around the neighborhood and it doesn't show any symptoms of overheating, no leaking coolant, hot smell, etc. but still shows almost 250 on the gauge.

Anyone have any ideas on what to check next? Could it be a miscalibrated gauge?

Sounds like you may have air trapped in the system. Did you burp it? Filling with the front end raised up can help too.

Don

I was thinking that too but I drained the system to install the new thermostat and then refilled, with a slight incline. I topped off the coolant and ran the car up to temp, topping off the fluid until no more air came up. I might try taking it to a shop to pressure fill it to be sure.

On Lateral G a suggestion is also to move the temp sensor from the radiator bung to the passenger side head. Could that be the culprit?

first thing I would do is get a mechanical gauge and put it in the head and see what it reads

yeah I think that's the goal for today and go from there.

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Originally Posted by spacepirate

I was thinking that too but I drained the system to install the new thermostat and then refilled, with a slight incline. I topped off the coolant and ran the car up to temp, topping off the fluid until no more air came up. I might try taking it to a shop to pressure fill it to be sure.

On Lateral G a suggestion is also to move the temp sensor from the radiator bung to the passenger side head. Could that be the culprit?

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You need to remove the cap, bring it up to temperature and then repeatedly squeeze the upper and lower hoses to burp it. Steeper incline helps too.

Pretty sure you have air....

Don

I did that on my last time but I'll try it again.