water coming from header tank cap

[Sir Brixalot]

While I was abroad water started coming from under the cap on the header tank a trickle soon became a stream. I replaced the cap with a VW one and replaced the tank. A week later and it's leaking from the same place. Unfortunately the bleed screw on the rad doesn't work so I couldn't bleed it properly and I initially thought this was the problem but the radiator is warming up so there can't be too much air in there..

Can anyone have a punt at what's causing this and also why isn't the coolant going into the top up tank instead of being forced out from under the cap of the pressurised header tank.

[marlinowner]

On my old van the pipe to the top up tank was blocked causing similar problems.

[Sir Brixalot]

Thanks. I have checked before but it was a while ago so I'll double check. It does draw from the top up though which is why I don't get whey it doesn't overflow back into it.

[ghost123uk]

water started coming from under the cap on the header tank...... I replaced the cap with a VW one and replaced the tank. A week later and it's leaking from the same place.

Is the water coming from under the cap then? If so, then the seal between the cap and the top of the tank must be not correct. That would explain why it's coming out there, rather than forcing the valve open to vent into the top up tank. I would check the condition of the bits that are supposed to seal and make sure you're tightening it down enough. By the way, don't grip the stub pipe whilst tightening it up, they break off rather too easily

[Ian Hulley]

The system isn't working properly and won't until you deal with the rad bleed screw issue.

Ian