My RS Turbo is blowing oil out of the dump valve!!!

It is a low comp 1.8 ZVH and is running 140psi across all four cylinders and has an oil seperator tank aswell.

Does not appear to be be smoking and the oil cap seems to be staying on aswell!

Any suggestions what might be causing it??? Could the cylinder head cause this or even the turbo??

Would take it somewhere but its out of MOT!!!

HELP!!!!!