Help Coolant overheating!

[eddymack]

Got back from a short drive today, parked up and noticed hissing bubbling from the bonnet. Looked under and coolant seems to be boiling and steam being forced out from under the cap. I have no steam from the exhaust, no gunk in the oil filler cap, and the temp gauge is rock solid at halfway.

Any thoughts?

Thanks in advance.

[mr mince]

Temp gauge doesn't budge until well over boiling point in these. First thoughts are blocked radiator or a dodgy thermostat causing overheating although a cracked cylinder head is a close third place.

[steve mmmph]

Too early for head, give the bloke a chance...

[buffallobob]

First of all the boiling is probably due to coolant loss so first things first get the system full again and see if it has any leaks if it had no leaks then it has been either pushed out of the expansion bottle by pressure from stat stuck shut but that would usualy start with high temp or rad blocked but generaly only shows after long runs and then exhaust gasses from head gasket or cracked head so first fill it up and see if there are any leaks
bob

[Townaceclive]

Have you got antifreeze in?

[eddymack]

No, just water.

Six months ago I was loosing coolant - steam through exhaust, advised the head may have gone so a bottle of Radweld later it held - and it's been water ever since though the level has remained reasonably constant.

Got it booked in the garage tmw so will report the diagnosis.

Thanks again all for your advice - a superb community forum!

[eddymack]

Oh and no leaks from my observations today.

[coldeedy]

looks like the radweld has given up, new head time

[eddymack]

Yes, I can't disagree.

This is what's perplexing me:

Surely if the radweld has failed I should get steam thro' the exhaust again, so has another part of the head failed?

I'm no mechanic clearly.

Will post news from garage tmw.

[coldeedy]

steam isnt always present, mine was cracked for a while before the steam started,