hdello again, ive had to change the head gaskets on my 95 sti, as the other half drove it with a split header tank, the gaskets are on and the engine is back in, i started it fine after a few loose wires, and it split the header tank again, i have done another compresion test and both rear cylinders are 10 and the fronts are 11 (is that about right?), so the back pressure isnt the head gasket failing again, so what could it be, cheers phil.

 

I hope thats not PSI if its bar your ok, if not your in trouble.

Readings should ideally be from 120PSI up even on all cylinders.

 

im sure its bar, so why the back pressure into the header tank?

 

Did you see any damage to the gaskets? How did the heads look,as they may have had a crack or pitting. Have you checked the thermostat?

 

i havent checked the thermostat, no, would that make enough pressure to split the header tank? wouldnt a crack in the head make the compression drop also.