Disappearing Coolant?

[dave_s1988]

Hi all

I have a 2002 mini cooper. recently i have been losing coolant from the expansion tank and i have to top it up at least once a day fully.

At first i thought it could be an airlock but since then I have have topped up more than the system can hold. I have had a friend of mine who has a garage pressure test the system and there are no leaks present.

Pulled off the other day however after filling up with collant to the max. line.

I stopped briefly pulling off the drive and there was a sound like water gurgling from behind the passenger dashboard and when i popped the bonnet up no collant was present in the tank. Could it be a faulty thermostat?

[chris@LloydBlackpool]

Quote: Originally Posted by dave_s1988 (original)

Hi all

I have a 2002 mini cooper. recently i have been losing coolant from the expansion tank and i have to top it up at least once a day fully.

At first i thought it could be an airlock but since then I have have topped up more than the system can hold. I have had a friend of mine who has a garage pressure test the system and there are no leaks present.

Pulled off the other day however after filling up with collant to the max. line.

I stopped briefly pulling off the drive and there was a sound like water gurgling from behind the passenger dashboard and when i popped the bonnet up no collant was present in the tank. Could it be a faulty thermostat?

Hi
Just check the thermostat housing,they are plastic so expand and contract with the engine temp,if you look down the right side of your engine (cyl head area) and check for a green/blue water mark down the sdie of the block and on the top of the gearbox,this is were the water collects when it leaks from the housing also check under the bottom edge of the stat housing incase is is damp
hope this helps

Chris

[Acallahan]

Mine is doing almost the same thing, when you get out of car do you smell anything like antifreeze cooking ? I have come to the the conclusion that its the thermostat or housing so purchased both and will switch them out when my schedule allows.

[dave_s1988]

i have checked all of the the pipework and traced it down to the housing etc and i cannot find a leak. iv had it pressure tested with no leaks found. I filled it up yesterday from an empty tank to just above the minimum line. I have just checked and i have now more coolant than i had yesterday which is odd it is now above the maximum line. im guessing it may have been airlocked but to have been airlocked for over 2 months seems odd. no smell of antifreeze though and no trace of coolant when it happens so fingers crossed it is all okay. my guess for the antifreeze cooking would be that it is either boiling or that it is leaking onto part of the engine so u should trace the pipe work from the tank and also check the tank for cracks or splits hope this helps

[dave_s1988]

After a week without any issues I travelled an 8 mile journey home this evening to a bubbling sound when i pulled up at my house. Opened the bonnet to see the coolant bubbling out from the expansion tank :s temperature gauge still read normal. Upon turning the engine off the coolant stopped bubbling and returned to the maximum line. as soon as i turned the engine back on it began to slowly bubble and creep up to the top of the expansion tank. no signs of leaking coolant other than a small amount that had bubbled over and also checked my dipstick and oil cap for creamy substance to make sure it isnt a head gasket problem. anyone have any ideas???

[mab01uk]

I suggest you replace the pressure cap on the engine filling point, fairly cheap and easy to do.......if the cooling system does not pressurize correctly due to a faulty pressure cap then the boiling point of the coolant is much lower, have known this to cure similar problems of bubbling in expansion tank on other Mini's so well worth a try.
Item 11 here:
RealOEM.com BMW R50 One 1.6i Waterpump - Thermostat

More info here including pressure cap:
Solving MINI Cooling Problems.......... - Forums

[Hull27]

The same thing happened to me about a month ago. When in traffic, or stationary it would dump coolant from the expansion tank. It just poured out of the pressure cap.
It was the cooling fan that had gone. My man at the garage says that they have a 2 stage cooling fan system. The first stage kicks in at a certain temperature (traffic jams etc.) the second stage kicks in at a higher temperature. My first stage wasn't working. There is also a temperature sensor that causes it to come on.
£170 for a new fan + fitting.

[mab01uk]

or fit this kit or a new resistor:
Forums - View Single Post - Solving MINI Cooling Problems..........

[Thomas@1320]

If you click the air con on make sure the fan kicks in, it should, if it doesn't check all the fuses int he engine bay.

[SRH990]

Had the same with the 2001 Mini One we bought for my daughter. First afternoon of using it after collecting it from the dealer got home to hear the water 'boiling' in the header tank and immediately thought the worst - head gasket.
The Mini doesn't have a pressurised header tank, the pressure cap is on the engine fill point, looking at the pressure cap there was evidence of coolant leakage so I suspected this might be the cause, the cap releases the pressure so the water boils. When I took the cap off the seal was in pretty poor shape and just twisting it caused it to split so as a temporary fix I made two rubber seals out of a bicycle inner tube to match the thickness of the original and refitted the cap, job done, no more loss of coolant or boiling.

I bought a new cap from the local Mini dealer for around £11 which is now fitted.