overheating

[gibbo1977]

Hi guys was heading along motorway earlier and put blowers on to full low as ac doesnt work next thing i know temp gauge is in the red and car goes in limp mode! Pulled over popped bonnet fan was on flat out opened coolant tank slightly and she spewed a little water. Let car cool and set off again only for it to happen again so put blowers on full hot suddenly it dropped back to normal temp but now shes blowing cold even tho she on high!! Any ideas much appreciated folks. My first thoughts were cylinder head, or thermostate
iain

[insanitybeard]

If the fan is working and there aren't any coolant leaks you can see & the system is holding pressure then I'd be checking the water pump next- the pump impeller can detach from the shaft meaning that the coolant isn't being circulated properly (although the water pump shaft is still being driven and rotating the impeller is not).

[gibbo1977]

Big job? Gotta drive 80miles home later lol

[insanitybeard]

The water pump is driven off of the alternator belt on the 1.8 TDCI so it's not as big a job as it could be (e.g, if it was cambelt driven), however, it's still bad enough if you're thinking about trying to tackle it at the roadside- if you can find anybody open on a Sunday who has the parts in stock!

You need to confirm the cause first of all though, head gasket failure could cause similar symptoms, but before thinking the worst I'd look at the water pump. Not so sure about the thermostat- I find it hard to believe it would fail like that whilst driving along!

[gibbo1977]

Thanks for your help m8. I take it if it is the impeller i will need a new water pump?

[insanitybeard]

Yep, if it is that then no repair is possible, a new complete pump assembly will be required.

[gibbo1977]

Apparently a casing was  cracked and they could only get new one from ford at Ã,£220+vat! New thrmostats and coolant boom Ã,£300