Overheating Mk 4

[magpie26]

Hi,

i have a mk 4 which suddenly decided to overheat (max. temp) at the weekend. Had a look under the bonnet with the engine running - water is clean but bubbling over the tank, fans arent working at all, the radiator isnt too hot to touch and there was also no loss of power. Think it may be the thermostat and hoping the head gasket hasnt gone but got to have another look tonight, any ideas?

[Rhyso]

Welcome 

is there coolant pumping around the system?

Could be your water pump - they tend to fail for a pass time sadly 

[magpie26]

Thankyou!

Im not sure as unfortunately, i only managed to get a quick look at it, will make sure i check later. Thanks for your help

[burnt01]

try removing the coolant cap cleaning both cap and bottle then do it back up.  A friends "just bubbled over" and it because the pressure was escaping through the cap and the water didnt circulate.  Therefore the heat didnt get too the thermo switch for the fan or even get to the radiator 
we had a spare bottle though

[roger1234]

I would start with the thermostat.

[vwdan80]

Hi what engine do you have? 

[gtibarnesy]

take the small pipe off the coolant bottle and start the engine, give it a little rev and coolant should come out.  If it doesn't sounds like a shagged water pump if coolant does come out the thermosat is probably stuck closed.