My coolant level is dropping about two cup fulls every couple of months,there is no coolant on ground just a small water drip on garage floor after about middleways underneath engine after driving it.

Could be your water pump is going bad

ok , can I assume you run green, yellow, orange ,pink antifreeze
in the radiator, not pure water, and check AF every fall for 50% consenstrations? yes.
then that water is normal Airconditioning condensate water that all cars drop to the ground. pure water it is.
THE A/C runs when you ask for COLD or Defrost.(front)
and works just like a cold beer glass in a humid tavern. it drips.

Hi Robert, No it is not normal for the coolant level to drop at any time. The BMW has a system which must be bled to free it of all air. The bleed screw is situated on the radiator and has a screw driver slot. Open the bleed screw and replace the coolant with the recommended coolant and then finish topping up with water until all bubbles have cleared from the system. Observe the level and if it drops again have a pressure test carried out on the system as if the level drops again, there must be a leakage. Likely places are hoses, and the water pump. If it is the water pump, the leakage may only be evident during engine operation, unless the leakage is severe in which case you will notice coolant dripping. Regards John

Raise the car front end as high as possible with a floor jack, fill the coolant tank to the top, run the engine until it reaches just short of overheating, shut it down and run water over the radiator, this will burp the air out. Repeat as needed. Don't let the coolant recovery tank run dry during procedure.

I'm not sure what your "ac drain tube" is, but it is possible that the coolant is what drained out the night before. This means that the coolant is hot. Hot coolant expands and will overflow if the radiator is full to begin with. Most cars provide a coolant reservoir to capture this overflow - and to which to add coolant. If your car has this reservoir, you should maintain the level for HOT or COLD (do not fill to the top)depending on whether the engine is cold or hot. If the coolant level in the reservoir is between the HOT and COLD marks, (not up to the top) and you're seeing coolant on the ground, you have a leak somehwere. A heater core that is leaking usually shows up INSIDE the car - on the floor for the front passenger - directly below the dashboard; as this is where it is located.

A puddle under the car should give an idea as to where the leak originates. Arrange to park on top of a sheet of cardboard so that any leak will drip onto it. Check it later in the day or the next morning prior to starting and driving off. If dry, reposition the cardboard under the car again, and start the engine and drive off the cardboard. Park and retrieve the cardboard and inspect for wat spots. In either case, if water is found, you can use the cardboard to approximate the location of the leak. Bear in mind that the leak could drip onto a part - and floow the part to a low point before dripping on the cardboard.

Some of the underhood A/C components will drip condensate if they are running in hot, humid conditions. This is normal. Condensate is simply water and is odorless and colorless. Coolant, on the other hand - is slightly thicker than water and is usually yellow-green or pink in color and has a slightly sweet smell. Coolant has lubricating qualities too, so it will be slippery. You will probably not be able to tell the difference between the two by looking at it is on asphalt; but touching it with fingers and looking for color & smell will.

A little coolant on the ground is nothing to worry about. Make sure that the coolant level is not dropping consistantly, and you should be ok. If it is always requiring that you add coolant, it is the sign of a leak somewhere.

Good luck!

I would pressure test your cooling system which would cause any otherwise unnoticeable pinhole leaks to spray a small mist of coolant if there was in fact a leak present. I had a similar problem with my wife's dodge caravan, I kept smelling coolant after she drove the vehicle for long periods and I checked the entire cooling system and inside vehicle for a potential heater core rupture and nothing was ever seen and coolant level always remained full. A couple days later I noticed the same thing and allowed the vehicle to cool down, I then pressure tested it at 16 lbs, I did not notice a drop in the guage but then I noticed 1 small drop of coolant coming from the water neck where I had replaced the thermostat several months back. I torqued the bolts down a little more rinsed off the area and have not noticed the smell anymore. That 1 drop of coolant would immediately evaporate once it hit the block but the smell was strong enough to get my attention and to figure out what was going on

low coolant level due to the leak is a problem. The water pump or the radiator or a hose to the radiator could be the problem.

Have the car filled up with coolant and pressure test it to 15 or so psi to see where the drip is exactly coming from at a garage.

Chances are the coolant is leaking into the intake/cylinder head and being burned in your exhaust. An easy test for leaks involves a pressure test of the system via the radiator cap at your local garage with an ultra violet dye in the coolant .

if it is leaking from the lower hose on the radiator then chances are it is dripping onto the ground and they wont notice it. Tighten the clamp and see if that helps.

If it is antifreeze, yes. It could be just water from a clogged a/c drain or rainwater leaking in from a bad seal.