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Head Gasket gone


ClioSport Club Member

Im losing water/coolant somewhere. Had it pressure tested - all ok. Oil is fine in header tank (please dont be the head gasket). After i went for a drive the other day I looked under the bonnet and there was a hissing from the water reservoir cap.

Please tell me that this is where the waters going.

  172 Cup, V6 255, Williams

Have you had a block test done? They screw a device full of blue liquid onto your expansion tank, run it up and if the liquid turns green/yellow, then there is exhaust gas leaking into the cooling system, a sure sign the HG is leaking.

When you have been on a run, and you undo the cap, do its give a short sharp hiss, or does it bubble and boil over out the cap with a lot of hissing and such? Again, this indicates an over pressuised system.

Is there any water in the oil (mayo type substance on dipstick or under filler cap).



ClioSport Club Member

Havent had a block test done - I work at a rover garage - will i need to take it to a renault place or can they do it here?

The oil is fine in the filler cap - Ive got a new water tank cap thing ordered - hope it sorts it out or im in the sh*t

Bad news mate sounds exactly like mine, changed the rad because I thought I was losing water throught there but no, the pressure was pushing it out of anywhere it possibly could because the Head Gasket was shot after having it changed no loss of coolant and that was 3 months ago!! Simple way to check is take it out for 15 mins from cold, then when you get back loosen the water resevoir lid, if there is water screaming to get out then it is most likely your gasket. Nice and long winded love it!!!!