I have owned my 08 Mini S for about two months now. Last week I got the yellow coolant warning light. I stopped immediately and added coolant (BMW coolant). Over the last week I have noticed I am slowly losing coolant. I can't see any visible signs of a leak. Any idea where I should check?

 

anything in the oil?

 

Nope, oil looks perfect.

 

must be on the floor then? lol not sure..

 

Perhaps there is a head gasket leak. Is the engine running fine? If it is the head gasket you will not see it as the coolant will go out the exhaust. We had that with one car we owned and it only became evident when the engine lost power.

 

check under the thermostat housing, coolant will pool there or be boiled off so no signs left on the floor or driveway. the thermostat housing is a common failure

 

This would be my guess also

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If the thermostat leaks (driver side of the engine), the coolant can get trapped on top of the transmission (there are ribs on the bellhousing). You may also have a small leak on the coolant tank, check for a crack on the bottom of the tank. The water pump is on the passenger side of the engine and can also create a leak.

You may also want to search on how to bleed the system, if you haven't found the bleeder on the thermostat.

There are how to's on how to replace these different items.

Good luck diagnosing it. My car lost coolant without dripping on the ground. I replaced the thermostat and found my coolant tank cracked. The coolant level has remained constant since.

Mike

 

More than likely it is either the Tsat housing or the water pump. Water pumps can have slow leaks and sometimes will not leak out on the floor where a Tstat leak usually does. I have had to replace both. If it is the WP, you will definitely see the signs of leaking on the front of the engine. They are a real pain to change. The new metal house water pumps have a longer shaft. I successfully notched my WP pulley to allow me to install it. I notched it on opposite sides for balance. The plastic WP housings I would stay away from.


Good Luck

 

do you smell anti-freeze . It could be something as simple as a loose hose clamp or coolant cap .