Help!!! Overheating Problem...

[dbcloud9]

First Car Project...

Problem i get is that the 240sx KA24e runs fine, and doesnt overheat until i turn the car off, then the coolant in the reserve starts to boil over, then lose so much coolant.

I have flushed my cooling system, and bled for any potential bubbles (i think). I say i think becuase i don't know when to stop checking for bubbles. I've run the car with the radiator cap off, raised the car, turned on the heater on high for about 30-60 minutes. It doesn't overheat, until the car is turned off.

Suspected Blown Head Gasket: I just completed a compression test to check for head gasket problems. My compression was Cylinder 1 = 195, Cylinder 2 = 175, Cylinder 3 = 180, Cylinder 4 = 180. (Specification compression Standard is 12.3, 175.

- Does my compression test look or appear ok?
- When do you know when you've there are no more "bubbles" in your cooling system?

[Bigsyke]

I would say your radiator cap is bad.

If the coolant in the overflow tank is boiling, something is wrong, however if it overflows then your cap is bad.

[dbcloud9]

The coolant boil out of the overflow tank (coolant reserve). that's why i lose coolant. If i let the car sit and idle it for more than 1 hour it doesn't overheat...however as soon as i turn off the car...the overflow (reserve) tank starts boiling with coolant from the radiator...the thermostat, and water pump has been changed.

[PinkPanther]

Are you sure its "boiling" out of the overflow tank? it sounds like your rad cap is just letting all your coolant escape the cooling system once your engine is shut off. You should test or replace your radiator cap and go from there.

[dbcloud9]

Let me try that. What about the my compression results. Have any opinions?

[johngriff]

compression is fine for a stock single slammer

[idlafie]

The coolant boil out of the overflow tank (coolant reserve). that's why i lose coolant. If i let the car sit and idle it for more than 1 hour it doesn't overheat...however as soon as i turn off the car...the overflow (reserve) tank starts boiling with coolant from the radiator...the thermostat, and water pump has been changed.

If you have coolant boiling out of the overflow tank, then you have some sort of blockage in your radiator or engine block. How old is the radiator? When you flushed your cooling system, did you just drain & refill or did you chemically flush the system?? What about your thermostat? Did you use a stock OEM Nissan thermostat or did you use a Kragen/Pepboys/Autozone thermostat?? If you used an aftermarket thermostat, you may want to pull it out & go back to an OEM Nissan thermostat. I've heard horror stories about aftermarket thermostats not opening up properly & causing cooling issue problems..

Anyhow, hope this helps...

ID