Stumped on hot temp gauge reading

[Vegas69]

I agree, use a heat gun to check the t stat housing or a manual gauge instead of the sender. You may have a bad gauge or sender.

[camcojb]

I always drill a couple 1/8" holes in the thermostat to let any air out of the block (if the thermostat doesn't already have them). I fill the engine with a funnel through the upper radiator hose (disconnected at the radiator). Once it won't take any more water I attach the hose to the radiator and finish filling the radiator through the cap.

It's critical to fill the block correctly, and the bleed holes in the thermostat work wonders to remove any air. It sounds like you have an air pocket at the thermostat; the thermostat won't open, and the engine temp will spike but the radiator stays cool because the thermostat is closed.

[Musclerodz]

Disconnect the upper radiator hose and back fill the block. Air is trapped on the backside of the thermostat and won't open. Air temp in the system always reads higher than water temp.

[camcojb]

Originally Posted by camcojb

I always drill a couple 1/8" holes in the thermostat to let any air out of the block (if the thermostat doesn't already have them). I fill the engine with a funnel through the upper radiator hose (disconnected at the radiator). Once it won't take any more water I attach the hose to the radiator and finish filling the radiator through the cap.

It's critical to fill the block correctly, and the bleed holes in the thermostat work wonders to remove any air. It sounds like you have an air pocket at the thermostat; the thermostat won't open, and the engine temp will spike but the radiator stays cool because the thermostat is closed.

Originally Posted by Musclerodz

Disconnect the upper radiator hose and back fill the block. Air is trapped on the backside of the thermostat and won't open. Air temp in the system always reads higher than water temp.

Did you get this figured out?

[spacepirate]

Had to go out of town for business. Nothing yet so I'm gonna try replacing the water pump. Also, sent the computer back to the tuner since the fans were cutting on too late. I'll keep everyone updated once I get this done.

[camcojb]

Try filling it the way outlined, with bleed holes in the thermostat. I doubt it's a bad pump unless it's leaking.