opinions

[ted]

if there is that much pressure in your cooling system it may be a blown head gasket combustion pressure leaking into your cooling system, but that is a maybe it could have just been been a shit welch plug fitment. because with a blown head gasket it should have blown the radiator tanks or a hose first.

 

[bazeng]

George, sounds like the most likely cause.

What have you done so far Harry?
Did you install a new plug?

To test your cooling system, take it to Dan/Springy and get him to do a pressure test on it.

Basically they have a tool that plugs into the radiator (replaced the rad cap) and then they pump compressed air into the system which is monitored via a gauge. Pump it up to your desired pressure ie 1.9 bar and see if you have any leaks or a pressure drop. If your cap was sticky and not letting the pressure out of to your overflow bottle, then this may have been the cause.

 

[S15ETA]

ive gotta get a new plug for it baz.....ill just loctite it in then when they tune it they can have a look over it all

 

[ted]

most radiator specialists also have a tool the place in the top tank which detects carbon monoxide from the combustion chamber in the cooling system 5 minute check. something i would highly suggest.