Coolant pressure

[Wibblyp]

I'm getting excessive pressure in the header tank. Builds up on a drive and is still present once cooled down. There's some gurgling from the heater matrix on occasion. Have bled the system and hoses get hot when driven. The coolant system is a nightmare to understand. Besides head gasket failure venting exhaust gasses into the system, is there anything else that could be causing this issue ? 1.8 non vvc,mg rad, head gasket done 6 months ago.

Thanks
Paul

[DotMatrix]

I would guess that you still had air in the cooling system.

[Dave VVC]

Try looking at the inlet manifold where the pipe comes out for the hose for the header tank (near the dipstick), it should
have a one-way valve, it allows air out of the manifold to the header tank, but NOT back to the cyl head, if it does, then
this is a way that air can get back into the engine, its a good idea to fit a 82deg stat as well, as this puts less stress on
the cooling system.

[Wibblyp]

I think the jiggle valve is absent. Got a thin wire and inserted it very gently. There is no ball bearing present and the wire goes all the way in. I have read that others have removed this in the past without problems. Perhaps someone can clarify the point.

Ta

[DotMatrix]

I have also read about removing this but never did it. I have always made it work with that in place