Rover 216GSi overheating (Honda engine, AT)

I'm posting this on behalf of a neighbour. I'm floored with the flu these days so I've not bothered my arse to go look...

"The car was bought two weeks ago as a run around for SWMBO for 300 quid. Ran like a dream until she was on the way to the shops. She called me saying there was a slight rattling noise and at this point noticed the temp guage was reading all the way into the red. Upon inspection it's dispensed all it's coolant (no wet road, no obviously leakage).

There is no white smoke from the exhaust when filled up and revved, but once it approaches temperature the coolant starts to overflow from the expansion tank."

I suggested blocked rad or stuck stat, but obviously alternative angles are much appreciated.

Unlucky.

Could also be the water pump at fault, not doing it's thing. This could be an open ended repair resulting in a head gasket job.

It does sound like the stat is not doing it's thing but I'd also check that the expansion tank cap vent spring may have gone slack. You may know this but the boiling point of water rises if in a containment and under pressure (this is how pressurised water reactors work). If the vent spring in the cap is not allowing the system to correctly pressurise under working conditions then it's bye bye to your coolant and ultimately your head gasket.

I'd change the stat first and flush the rad with a hose pipe (drop the inlet and outlet hoses first), correctly refill and bleed the coolant system, then run. If it boils over again, put a piece of decent plastic bag over the expansion cap filler, screw the cap down on the bag and try again.

PDH