Expansion tank

[TVR8BLACK]

After a good drive no probs and temps raise and lower as normal
But when I stop and park up I get three blasts of steam that come out of the expansion tank cap
Have I overfilled tank or maybe faulty cap when cold tank is almost empty

[Gazzab]

Could it be either time for a new cap or bleed the system of air?

[jackwibble]

Sounds like a faulty valve in the cap is a good possibility cheap swap go for genuine VW one then try a bleed as Gazza said.

[TVR8BLACK]

I've ordered new Audi cap as the tank is from an Audi 100 £3.50 so may be just faulty also I'll bleed system too