There has to be a leak somewhere, have it pressurize the leak will show up somewhere.

 

I just had mine fixed couple of weeks ago. I had my coolant system tested by a coolant pressure test. It turns out that my coolant tank had a crack, got the tank replaced for $220 with labor, new bmw coolant and tank. If your still under warranty go to the dealership if not find an independent shop that has a pressurized coolant test system.

 

This topic is very interesting since i have to top my coolant every two weeks or so. But my issue is much more serious since its blowing the white smoke. Ill see what the mechanic says today since its at the shop now.

 

I had similar problem, no sign of leaks and level was ok for weeks then suddenly a litre of coolant would vanish.
Then one morning there was a large puddle of water under car, heat exchange had blown,

 

Its located near the top of the engine, and runs the entire circumference.

 

I might be wrong but I think you may have coolant in your oil.

 

Going to the dealer next Wednesday. The last time it was there, the pressure check was showing everything was OK. I'm hoping this time they will find the issue being it is happening more frequently. I will keep everyone posted. Thanks for all the replies and keep them coming. From what we are seeing, I'm not the only one with an issue like this. Oh...1 more thing, the SA said my 545i doesn't have the crossover pipe that goes through the engine.

 

Interestingly enough, I am having the same issue and my 04 545, it is at the dealer now. When I first mentioned the low coolant issue, they found a crack in the tank and replaced that. Three weeks later I got the warning and they topped it off and said that was normal after it gets refilled. Then three days after that, I noticed a huge puddle under my car and I took it back to them. Will let you know what they did when I get the car back. 69k miles here.

 

wow i have 68k miles on mine. The mechanic told me he did not find anything weird in the combustion chamber and that all there was was condensation from the engine needing to reach operating temperature and once it reaches it, the car stops smoking. OK so thanks BMW for not giving us coolant temper

 

I am having the same problem on my 2005 545i with 53k on it. The car under CPO and I had taken the car in about a 6 weeks ago with same issue and they said it was nothing, re-filled and pressure tested the system. I have owned BMW's since 1990 and this is just a lame excuse by the stealer because most of them just use diagnostic tools and are not true mechanics. Heck I don't think they have a single guy who can work on my '76 2002. I plan on taking it to a different dealer as I used to take it to BMW of Fairfax for all the service here in DC metro. BMW's aren't cracked up as what they used to be as I have owner about half a dozen of them and their dealer customer service is horrible. I also own a Porsche 911, Infiniti and a Honda van and BMW owners should see their dealer service.