So I've recently noticed that I have a coolant leak in my 12' countryman S fwd. It doesn't leak as I'm driving, but rather leaks as it sits for several hours over night or at work.. it seems while the car cools down. I've recent been cracking the cap on the expansion tank to release pressure so I don't lose any coolant.. it's a strange leak.. and without doing a pressure test or putting it into service mode to further investigate.. I've almost come to the conclusion that it seems like my radiator needs to be replaced.. I can view through the lower grill and notice coolant residue on the top of the intercooler.. I just hit 85k on the odometer.. any help or thoughts would be greatly appreciated as I troubleshoot when I have the time

 

I would say the first item is to located where the leak is and you seem to address when it leaks (not under pressure when running?)... That is key. Usually when there is a leak when not running this is the water pump...

 

I agree.. but I'm noticing is the leak coming more from the front right directly under the intercooler in the 1st pic and on the ground under the lip of the valance of the bumper. In the 2nd pic is where I see coolant following along the bottom of the AC condenser. Mind you I was just parked facing downward on a side street on a slight incline

 

Leaks usually start up high and travel various paths down as you're finding. Have to try and clean it off and trace it upward to see how high up it goes...

 

Sounds like what mine was doing too when the water pump started leaking. I couldn't see where it was leaking, so I stuck some cardboard under it overnight and found some drips right under the passenger side of the engine…….right under the water pump. If you can get under it and look, you can probably see dried or wet coolant on the bottom of the pump or friction wheel.

 

I have a lift at work but just haven't had the time to be able to look.. the leakage isn't on the passenger side where the pump is, but rather in the drivers side in the front end whether or not parked on a slight incline or flat surface.. I checked my expansion tank for leakage and there is none.. that coolant line that leads to the turbo I replaced in May when it broke at that T section after trying to remove it when I replaced my thermostat housing along with the expansion tank lower hose.. no leakage from the upper radiator hose either.. I have yet to pull the radiator support crossmember for further investigation.. I feel that the radiator may have a tiny crack in it.. the leak is very very slow. Again when I release the pressure via the expansion cap the leaking doesn't occur

 

I have several instances on various vehicle where these plastic radiator tanks will crack and have leaks like this. When cold and small they sometimes seal up. When they heat up the crack expands and gets worse to the point where it could make a small explosion of coolant like a hose burst.

 

So my thoughts are that I may just replace it with this aluminum one

 

Wow, that is really inexpensive. I'm intrigued! lol.
If its on the drivers side, and the thermostat and expansion tank are ok, and the hoses are fine, then yeah.... that eliminates several things. it probably is something like a crack in the radiator tank or something..... hard to say from here...heh heh… Bit the only other obvious thing that comes to mind is the plastic pipe between the thermostat and water pump. but its on the back side of the block, I doubt the coolant would migrate to the front from there.

 

A buddy of mine told me about the FCP euro site.. they have tones of OEM mini stuff it seems and they even give a lifetime warranty on what from what I see is all parts..

 

Something odd but interesting just happened that I'm going to look into.. I just came across this random thread ( you can see in these screen shots. I am getting a buzzing like noise after shutting down my car just as described

 

Definitely check that one out.

 

There was a recall or warranty extension on the auxiliary water pump. Call the dealership, you may get it replaced for free. Another reason to get a kazoo like buzzing noise when you shut it off, could be the the turbo boost pressure converter. The kazoo sound is a classic symptom of it needing replacement.

 

It's a $40 part so I will more than likely just replace it.. I can get parts @ cost through my shop.. seems like a no brainers )

 

I take it that the pressure converter is just another term for the solenoid valve?