what is wrong

no overheating,no white gunge in oil cap,no power loss,no white smoke,but my water bottle fills up and bubbles when hot,but empty`s when engine off,steam escapes from filler bottle cap........so far everyone says immediately its head gasket,but with no other sign can it be a fault with water pump,as the rad fans come on ok,i am at my wits end...please suggest a remedy

sharrison said:

i am at my wits end...please suggest a remedy

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sharrison said:

no overheating,no white gunge in oil cap,no power loss,no white smoke,but my water bottle fills up and bubbles when hot,but empty`s when engine off,steam escapes from filler bottle cap........so far everyone says immediately its head gasket,but with no other sign can it be a fault with water pump,as the rad fans come on ok,i am at my wits end...please suggest a remedy

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Unfortunately no matter what is the real problem, the answer usually given is the head gasket:doh:

To me it sounds like you have an air lock in the cooling system and a faulty coolant tank cap that is preventing the coolant from pressurising and causing it to boil.

Bleed the cooiling system and re-fill as necessary and fit a new cap at the same time - hopefully this will solve it.

You have not said what engine or year, but on the earlier ones there was a problem with the cap and top of filler bottle. it just may be the problem. the new ones are modified

KV6?
if it is, check the thermostat housing - common cause of coolant loss.
replace coolant bottle and cap (for bottle with coolant level sensor)

then report back.