Strange overheat

Took the 2.5dse out yesterday. Went down the motorway at around the legal limit for 30miles. Pulled off as I was meeting my son and waited for around 5mins before he arrived with engine off. Set off again and within half a mile temp gauge hit the red and car went into limp mode. Pulled up into lay by, lifted bonnet and car was on the point of boiling. Strangely the internal heater wound not give any hot air. Let the car cool, slowly loosened the expansion tank top to lots of hissing and eventually a warm water shower. Refilled the tank. Started car and all was fine, drove nervously though city centre traffic and eventually back home, used the car this morning, no issues.

I has crossed my mind that this has happened before when a friend used the car. That time it blew a pipe off the expansion tank, I put a jubilee clip on it after that but never investigated the potential fault as I put it down to no jubilee clip.

Car has had a new water pump with metal impeller only 2 months ago. I am thinking possible intermittent fault with thermostat. Any other ideas or suggestions. Been slowly working through the car as wont to be able to use it to tow caravan but this has my stumped!!

Viscous fan fecked. If all else is OK, you can add my aircon fans mod for cooling.

As keith said, roll up a newspaper and when the engine is hot and running, insert the paper into the fan, if it stops it then it's buggered, if it shreds the paper then it's ok and I'd look at replacing the thermostat.

mick

Surprised that is what you think but will test it. Interested as to why you think that would cause the lose of internal heat, but a guess would be that over heat has caused an air lock.

ShaunPDisco said:

Surprised that is what you think but will test it. Interested as to why you think that would cause the lose of internal heat, but a guess would be that over heat has caused an air lock.

Click to expand...

Vapour lock when it boiled. The engine generates a lot of heat at speed but the ram airflow is enough to keep temperature under control. When you slow or stop there is a thermal overun and no ram air, so if the viscous is fecked it will overheat

Datatek
Just been reading through search results and your air con mod appears a few times. Post whee quite old, is it still relevant?

Got the car to operating temp, stuck the paper in and..............fan stopped dead!!!!! So from what has been said the fan should have some sort of resistance when at normal operating temp.

Datatek, will send you a pm. Would you please forward the detail of air fan mode.

Shaun

Might have sent more than one pm. Didnt have save option ticked so didnt think it had gone........opps!!

Check the RAD gets hot all over.