The other day while checking the oil on my wife's '05 MCS I noticed that the coolant level was below the minimum line on the ex. tank.

I added a bit to bring it up to the middle position between the min & max lines with the intent of checking the level again the next day. The next day the level dropped. It has been my experience that no coolant loss should be evident in a vehicle unless there is a leak somewhere in the system.

As per previous forum posts I checked the ex. tank and various hoses, etc., all were bone dry. I drove the car and brought it up to operating temperature, parked and opened the hood. After a thorough examination - lo and behold, "steam", if you will, ( an extremely small but persistent amount) coming from what appears to be a tiny pinhole on the upper right of the forward most radiator. The leak. It appears to have been caused by the pointy end of a small stone or asphalt pebble which somehow shot through the grill, apparently at exceedingly high speed. The reason I suspect this is that I found a bunch of them under the hood area.

The steam from the pinhole was quite evident when I made a concerted effort to examine the radiator. However, if one makes merely a cursory examination such could be easily missed. I would urge all who have experienced a lack of coolant, however minor, to carefully examine the radiator(s).

I have made an appointment at the dealer and duly informed them where the problem lies.

Best,

William

 

I lost almost all my coolant (and overheated ) only a month or two into owning my car... it was the seal on the pump... it leaked out & where it hit was a heat shield so it evaporated all away... so I never noticed a leak on the ground.

But, I'll watch closely for pinhole leaks too now... thanks for the tip & hope your repair goes well.

 

Thanks for bring this up. I have had coolant loss in my '05 MCS as well, and have topped it of twice. Last month I took it to the dealer for the yearly free oil change, and mentioned the disappearing coolant to them. The dealer says coolant loss is normal and re-filled the tank. One month later - tank is empty again!

 

I'm not sure coolant loss is normal. I have never had a car that lost coolant unless there was a leak somewhere.

 

Coolant loss is not normal.Any knowledgeable mechanic will tell you that.Go through and check the hoses connectors and especialy coolant tank and the cap.Ive seen some caps that leak because the are not snug.Also seen defective caps.Also make sure the fan fuse operates.The smell of coolant is distinctive so if you have a leak you should be able to pickup the smell.

 

I too have had a loss of coolant and appreciate the tip. I drives me crazy to hear, yet again, BMW/MINI calling something normal when it is simply not just to avoid warranty work. I've had them say that for so many things on several cars, even when there is a TSB out that specifically addresses the problem at hand, and have had to go through way to much effort to bring the dealers to do the right things and actually find/fix problems. Sorry for the rant but, as you can see, I am at the limit on this...