View Full Version : Northstar overheating!

06-28-05, 12:17 AM
I have a 97 with a northstar 4.0 engine.

When driven at speeds of 60 miles per hour or less..the temperature is normal. but at highway speeds above 70 it will get to the red area if i continue. I am not loosing water unless it backed out the recovery tank. I replaced the top on the tank and now it does not back out at all (i am afraid it does not release pressure). I have replaced the thermostat and I took it to gm and they said it was the radiator..which i independently replacedbut i still have the same problem. i have flushed it and added the tablets. as I said i don't have to add coolant. I don't have water in my oil. one thing i noticed is that my hoses get really tight..like pressure is not being released....any suggestions are welcome..thanks

06-28-05, 07:06 PM
Well the system should have about 15 psi when hot. That may explain the "tight hoses". Over pressurization should not cause overheating. Does the cap hold pressure? Is the belt tensioner applying enough tention to the water pump belt so as not to slip? Is the purge line free flowing?

06-28-05, 07:51 PM
I have an 18 psi cap a new one from the dealer ( only comes in 18 psi now)

the cap does hold pressure but i was thinking it was suppose to release pressure once it got so high

I don't see the belt slipping but as i said i was trying to figure if it was worn or not because it is not fully engaged as is the tensioner suppose to have room to move towards tightening the belt ..or is it suppose to be all the way tight with no room to tighten?

where is the purge line? the line on top of the coolant jug? it is not plugged it is free..however it connects to the throttle body...could it be clogged in there?


06-28-05, 09:32 PM
Overheating on the freeway is a sign of a missing air diverter... at least on camaros... I don't know if you have one or not....