Cooper water loss

[sja]

Hi I'm after bit of advice on the wifes 56 plater cooper. First noticed the fan constantly running, temp gauge is fine .checked and expansion tank totally empty. Filled and few days later empty again, fan on all the time. Dealer checked it and said it was a crack in temp sender housing. But we have had it back a week and it's still the same but I feel it's also down on power.. Dealer said it's fine and was prib just an airlock.. Told them to keep it for a few days, the fan shouldn't be running all the time surely and it's not revving cleanly, really struggling..

Any ideas on what's wrong?

Cheers

[Worzel]

Hi,

Couple of easy checks to do:

Is there mayonnaise under the oil filler cap? If so this could be a sign of head gasket failure
Check the dipstick, does it have mayonnaise on it? This could also be a sign of head gasket failure

How old is the car and how many miles has it done?

If you have a local garage that you can trust, get them to do a compression check when the engine is hot, they should also be able to carry out a check for CO (product of combustion in the cylinder) in the cooling system by using a kit where a liquid will change colour based on whether there is any combustion gas entering the cooling system.

Hope this helps,

Jon

Edited by Worzel on Tuesday 14th September 20:06

[Tsippy]

Probably the thermostat housing, could you see where it was leaking under the car? It's a common fault unfortunately, and if they changed that part they probably did not bleed the system correctly after refilling the coolant which would cause airlocks and drops in coolant levels until the air is gone.


Just keep an eye on it, mine dropped for about 2 weeks (100 miles) after the housing was changed and is now fine

[sja]

Cheers, it's at dealer so I'll give them a bell tomorrow. It's the down on power and constant fan that's worrying me.. I can appreciate it may fall after they changed the housing.. I'll see what they say.. Oh and it's only got 11k on it..

[Tsippy]

Mine is a 56 plate and failed at 16k miles, my sisters is an 06 plate and failed at 8k miles

I'm surprised a recall has not been issued considering how common the fault is.

[sja]

Car back from dealer. They had it for a week and pressure tested it. No leaks at all..

However I filled the expansion tank when they returned it right to the max line. A week later it the water level is down by an inch. Its def down on power as well, not revving as cleanly but dealer said its ok. No

So im stuck now!! Any ideas where the leak is?