BMW Repair: white smoke coming out of exhaust -1994 bmw 325is, coolant leaks, 1994 bmw 325is

Question
First of all thank you for your time. I have a 94-bmw 325is. I am constantly refilling the antifreeze, more often if i am using the air conditioner. Sometimes, but not always, an excessive amount of white smoke comes out of the exhaust. For example, today I was checking the antifreeze while the car and air conditioner was running ( i know, bad move) of course antifreeze spilled out of the top. I tightened the cap quickly. Within seconds alot of white smoke poured out of the the exhuast. Also, at times when i first start up the vehical white smoke pours out excessivly from exhaust, lasting for about 4 to 5 minutes. I appreciate you helping me rectify this promblem and saving me from future promblems. Check engine light does come on sometimes but then turns off. Also, how do I turn off the red airbag light in the bottom right of the dashboard. It came on after I got the windows tinted.   THANKS AGAIN. David Koenig.

Answer
David,
 You shouldn't open the coolant tank after the engine is up to operating temperature.  You are lucky you didn't get burned.
 White smoke is usually coolant being burned inside your engine.  Somehow coolant is leaking inside, and being burned with gasoline, and it produces white smoke.  First I would recommend that you make sure the car is not leaking coolant from a hose or other source.  When you get home, and park the car for the night, slide a peice of cardboard under the car, and place it underneath the engine.  In the morning, slide the cardboard back, and look for any antifreeze leaks.  

 If there is a leak, you should fix it first, before anything else.  Coolant leaks are "generally" very simple to find, because they often happen around the hoses.  Once you have any leaks fixed, keep and eye on the coolant.  If the coolant gets low, and there is no antifreeze on the ground.... then it is being burned.

 Most likely the headgasket is cracked, and it's allowing coolant to seep into the cylinder and that's why you are loosing some coolant.  Headgasket replacement is probably the only answer.

 The airbag light can come one for many reasons.  But to reset the light, you have to use a scan-tool and reset it electronically.  It's most likely a sensor or something similar.

 Hope this helps,
 Josh