Hi guys,

I've recently had a couple of issues with my vRS starting to overheat. I've noticed the gauge start to creep up towards the red on long journeys after constant driving at 70-80mph so I back off to 60mph and the gauge readout falls. I've definitely been losing coolant and I'm certain its not the head gasket as there is no sign of emulsified oil and no bubbles been blown up through the expansion bottle.

However, the heaters sometimes blow cool air even when turned round to hot, more so when the car is starting to overheat. I've been told I could have an airlock but would this give the above symptoms? I've felt the lower radiator hose which feels pretty flimsy and the top hose isn't overly hard either. Is there anyway to properly bleed the system, i.e. a valve somewhere?

A trickle of water returns to the expansion bottle from the waterpump but this seems a small amount and may be just caused by the natural expansion when the water warms?

I'm thinking a broken impeller maybe although I requested a metal impellered waterpump when I had the cambelt changed. I'm keen to get this sorted asap obviously as if the temperature sensor is reading correctly it'll only be a matter of time before the engine goes pop!

On short journeys to work its fine, even on the motorway. Only seems to overheat under long periods of constantly higer revs.

Classic sign of tiny crack in cylinder head gasket, which only leaks under load. First however, replace the thermostat and temp sensor together if you are not loosing coolant.

If thats the case would it blow bubles back though the expansion bottle under load? If so, I'll check that out. There is no steam coming from the exhaust at all, under load or not but it is wet below the expansion bottle area which is leading me to think that water is being boiled out from here?

If thats the case would it blow bubles back though the expansion bottle under load? If so, I'll check that out. There is no steam coming from the exhaust at all, under load or not but it is wet below the expansion bottle area which is leading me to think that water is being boiled out from here?

A tiny head gasket leak on these engines (very high compression) tends to pressurise the coolant beyond the expansion cap blow off pressure, but only after a high speed run. Sniffer test often shows nothing, as the gases dissipate too quickly and are not present at idle. You could try a coolant PH tester to see if any gases have migrated into the coolant.

However, if your thermostat is stuck shut, the engine will overheat, again causing coolant to escape past the pressure valve on the expansion tank.

my thermostat was seized shut the other month. car lost coolant through expansion tank top. dint overheat but maybe worth a try.

try bleeding the water system up yourself.

failing that take the thermostat out and re-bleed it up.

i thought id done the head gasket in but it ran fine without stat in it and £20 for a new stat good as new again

hope its nothing serious

Sorry , sounds like water pump to me

What happens is when run fast , with a bit of the impella breaking off , when driven slow , the water pump can keep up

But driven fast , the impella can not keep up , so will get the temp guage up , and if gets too hot , will seize the engine

I am sure you dont want that now do you????

Sarah