I have coolant leaking onto the garage floor from what looks like it would be under the engine and centered between the front wheels - in the same area where the A/C would drip to.

Haven't jacked up the car yet but just posting to see what I might find when I do. We are the second owners. This would be the first issue we've seen besides the external trunk release button no longer working - 43k and always dealer serviced. The extended maintenance that was left on it was a big plus though that just expired.

Coincidentally, in the mail we just received the Herremans VS. BMW NA Settlement lawsuit info that concerns water pump failures.

 

You need to get it up on a hoist and find out where the fluid's coming from. It could also be the thermostat housing, or one of it's many connections. There's also a swivel fitting under the coolant reservoir that's been reported as failing. I've replaced both t'stat housing and swivel but still have the OEM pump --- '07 MCS.

 

Much appreciated! Will do. Keeping my fingers crossed.

 

Ok so today I filled up the expansion reservoir to the max line with a 50/50 mix using Mini coolant and distilled water. The car sat in the garage - no driving at all. A few hours later I realized the tank had drained. Everything was dry around the tank because the garage is like a sauna right now with this heatwave we are experiencing in central Pennsylvania. There was just the puddle on the floor.

So I figured out how to remove the tank and I saw the swivel you were talking about. I removed the hose from the swivel and brought the tank in the house and filled it up with water, keeping my thumb over the swivel opening. Nothing drained out, so I am at a loss.

I put everything back together and put a little water in to see what happens. Posting this in the meantime. If I do have to replace that swivel, how do you remove it from the tank?

Thanks again!

 

When this swivel leaks, it's usually pretty obvious --- the swivel will be wet. It can be observed by just loosening the tank mounting bolt and lifting the full tank, without removing the hoses. As for replacing the swivel, it's part of a larger hose assembly, and not a separate piece (on my '07 MCS). You should be able to find it on the RealOEM site --- http://www.realoem.com/bmw/enUS/select --- a popular illustrated parts list. If you buy the OEM assembly, it will be obvious how to remove the bad one. If the swivel is defective, it might be just a bad O-ring on the inside. Frankly, I don't remember how the swivel comes off the tank --- play with it and you should be able to figure it out.

You need to find some wet spots on the engine or hoses. That should tell you what to change. Keep looking 'til you trace it to the highest wet spot. Coolant can leak from one source, drip or run down nearby surfaces, then puddle several feet away from the original leak. The thermostat housing has 4 - 6 hoses plus a gasket to the engine block --- any one can and often does leak.

 

Another place to check is the oil filter housing, coolant runs thru it. Also the aux water pump is down there, used to circulate coolant thru the turbo when the car is shut off so the turbo cools off. Mine warped and had to be replaced. These cars have lots of coolant hoses. Look at realoem.com in the engine and in the radiator illustrations. The hoses are not all shown together.

 

I appreciated everyone's input on this. It ended up being the thermostat. After a few hours at Mini of Allentown it is all taken care of. They have been a pleasure to deal with in the 2 years we owned the car. I like the idea of saving money and working on my cars but that cramped engine compartment does not make things easy!

When I first realized there was an issue, I had focused on the expansion tank because I had filled it to the max line when I first noticed it was empty, but then a few hours later it was empty again even though the car did not leave the garage. That must have drained into the hoses to make up for what had been lost. I did not think there was enough 'gravity' there for the coolant to move out of the bottom of the tank and through that little up curve on the hose that attaches to the swivel underneath.