OverHeating

[ChemDog]

Need some help here. My baby is overheating intermitantly. If I drive normally around town it runs right in the middle. But if I get on the freeway or run it hard then the temp shoots all the way up and pops the rad cap. I have replaced the cap with a new one. When I went to change out the thermostat with a new one the originall owner had removed it. I installed the new thermostat and bled the system but it keeps doing it. The upper rad hose will get really hot and the bottom hose is cool to the touch. I have checked flow across the rad. I have romoved the water pump and chked it for bad bearing or damage, nothing wrong there. I just dont get it. It will sit in the drive way and stay right in the middle but the minute you run it hard she over heats. Someone help please.

[allenms240]

Are you sure the thermostat is in correctly with the nipple on top? A lot of people have trouble with this. Also, is the system bled of ALL air?

[ChemDog]

Yes it is in right. I bought it from Autozone but after reading some of the other issues with overheating on here I am going to go get a different one. I have bled the system and bled the system. It is the wierdest thing. I can cruise all day long in it and nothing but the first time I get on it it shoots to the top of the temp gauge. The upper hose is hot and the lower is cool to the touch.

[biggie]

Normal for upper to be hot and lower to be cool.

Did it overheat once before this issue started? Sounds like a small leak in the HG.

[ChemDog]

Ok so now it is getting wierd. I replaced the Autozone thermostat with another one from a different provider. Still does the same thing. I have bleed the system more times than I can count. Now when I let it run without the cap on it starts bubbling water out of the rad neck. If I add more water to it, it sits for a min and then starts surging water again. The car runs great other than the overheating. If I drive the car the temp will go all the way up shortly after starting and then settle back down into the middle range. Could the temp gauge be bad?? The speedo and the tach dont work, but the gas gauge and the temp and all the dummy lights operate.

[biggie]

Don't think its the gauge since it seems to be actually overheating.

Still seems it could be a leak in the HG to me.