Hello Group -
I recently bought a house which has a driveway with a pretty nice slope. When I park my jeep (facing downhill), my coolant bubbles up and returns to the reserve. Does anyone know why? Is the car over heating? My temp gauge shows about 200 all the time when I'm driving.. The car is a 1998 Jeep Wrangler. If you have any insight on this - could you please email me at snipped-for-privacy@optonine.net. I would truly appreciate any insight the group can share with me.
Thanks - Matt
not a real good idea to post your email in the clear, too much spam.
my two cents on this.
Your system has some expansion and probably a bit of air in it. When you park the pressure drops to the point the little valve in the radiator cap will open up and allow excess coolant (usually air if your parked level) out and into the overflow bottle. Since your parked nose-down it's going to be mostly water as the air will collect in the upper hose and engine.
It could be you simply need a new radiator cap.
Other than that, it's normal.
Close. The pressure needed to force air/fluid out into the overflow is the system pressure - 15 PSI nominal. The return direction to suck fluid back into the radiator/engine requires a very small vacuum. Agree on the result - need a new cap.
You also need to bleed as much air as you can out of the system. If you have an air bubble that gets caught in the rear of the engine when you shut down, the temp can rise pretty high which will force even more fluid out where it should mostly air escaping. Parking off-level, especially nose down, can cause some screwy radiator problems if you have any trapped air.
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