Stumped on hot temp gauge reading

[spacepirate]

Hey guys,

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?

[CamaroAJ]

Where did you put the temp sensor? Is it close to ambient air temp after the car sits over night or does it read way off when looking at the ECM data with scan tool? If you put the gauge sending unit in the passenger side rear of the head then it's going to read higher than the driver side front of the head.

[spacepirate]

Mine is on the radiator passenger side right below the steam and radiator out. Is this what you're talking about? Sorry the pic keeps uploading upside down.

[randy]

Move it to the passanger head on the rear. Also hook up a scan tool if the temp still shows a variation and read what the ecu is seeing. Pretty simple

[130fe]

I have the same setup- factory sensor in the drivers head, entropy sensor in radiator. I have found that there is about a 10 degree difference between the two. Is your radiator filled to capacity? It sounds like you have air in the system.

[spacepirate]

I don't think there is air in the system. I filled it up, ran the car and kept topping it off until it stabilized and couldn't see anymore air coming up.

Are you saying you have two sensors? One in the radiator and one in the head?