I have a 2005 Evo and yes I have popped out the freeze plug under the water neck two times now going to 3rd and getting into boost. This is a new MAP 2.3, ported head with HKS head gasket L19 head bolts. Yes the head has been retorted. I used OEM plugs & Green LT. Has anyone tried to lower there coolant pressure with 50% water/glycol mix, or water/Evans coolant?

 

what radiator cap are you using?

 

Are u not running any coolant or something?

Even if it was a bad cap and it didnt vent the coolng system shouldn't build up that much pressure IF that if what's blowing it out. Its weird cuz I would think a hose or something would blow off system if so.Maybe bad hg and its pressurizing the cooling system?

 

Stock rad and cap. running 50/50. I'm going to run a pressure test on my coolant system today.

 

What happened with the pressure test? and did you let it run without it pressurized and see if it builds pressure on its own indicating a bad head gasket?

 

I did a coolant pressure test. Set it at 15psi. Let it run. No movement at all in the gauge. Did the 2step. The pressure dropped a hair to 13 to 14. I ran the car up and down the road at 26psi boost. No more issues.

 

So it just fixed itself?