R50 Pushing Coolant Out Still

[Blindaviator]

So a while back I posted about my 2001 R50...

Since I purchased the Pathfinder back in February I have had an issue with it pushing coolant out into the overflow. Running around town it has no issues but once I hit the highway is where it starts to have issues. If I run at least 10-15 miles it will push enough coolant out to fill the over flow tank. If I run the A/C it is a LOT worse. Once it sits overnight it will usually pull the coolant back into the system filling it back up. At no time has the temp gauge ever moved above it's normal level.

Since then I have replaced:
Radiator Cap
Water Control Valve
Thermostat
Radiator
Water Pump
Fan Clutch

I have used the chemical test for unburnt hydrocarbons in the coolant and it was negative. I also purchased a pressure tester and the system will hold 14 lbs of pressure for 20 minutes without dropping (cold and hot engine.)

I'm still racking my brain on what is causing the issue. I have tested and replaced every thing that may be causing issues.

Any thoughts??

[Blindaviator]

Just put the pressure tester back on the radiator after it cooled down some from a run that caused it to push coolant out and it held 14 lbs for like 10 minutes.

Decided to pressure test the cap (replaced a few months ago) and it wouldn't hold any more than about 4 lbs. Will head to the parts store tomorrow for another new one and will test it there in the store. Want to make sure it isn't a problem with the tester.

If it is having issues with holding cap pressure then that would be most of my problems with it pushing past the cap.

[Niti QX4]

Did replacing the cap fix it?

[Blindaviator]

Did replacing the cap fix it?

New cap didn't change a thing. As a famous detective once stated "when all options have been eliminated, whatever remains (no matter how unlikely) must be the truth"... At this point since I have replaced everything that could be causing an overheating problem the only thing remaining is a head gasket... So time to look at getting an engine...

[atro]

im having the exact same issue right now.