Topic: radiator over flow at idle

[snowrun]

I just replaced a head gasket on a 22RE truck. The coolant is being pushed out of the fill opening at idle, but not with a little throttle. The head checked out fine & no obvious cracks in any cylinders. Is this normal radiator pressure or what else should I look at??? Water pump? Thermostat?
Thanks for any info

[BigMike]

Yes, this is normal. As an engine warms up, pressure builds in the system and the radiator cap is designed to hold back the pressure to about 14 psi before it allows any coolant to pass to or from the overflow tank.

If the engine is BONE COLD then it will not overflow at an idle. If the motor is bone cold, them remove the rad. cap and fire it up. The coolant should not do anything for about the first 2 mins, and then it will start to rise and overflow out the radiator as the engine is begining to warm up.

[snowrun [OP]]

That's exactly whats happening, I knew the system is pressurized, I guess Ijust never opened the cap with one idling before.
Thanks alot!

[79coyotefrg]

to keep air pockets in check,  i always drill a 1/8  inch hole in the side of the thermostat