BMW Repair: white smoke from the tail pipe, water coolant, combustion chambers

Question
hi,

my car is  A 1993 BMW MODEL.
I HAD THE WATER PUMP REPLACED DUE TO OVERHEATING.
3 DAYS AFTER THE REPAIR THE WARNING LIGHT IN THE DASHBOARD WAS ON.
I CHECK THE WATER RESERVOIR AND THE WATER COOLANT WAS BELOW THE 50%.
I HAVE TO ADD COOLANT ONCE EVERY WEEK
PLENTY OF WHITE SMOKE IS COMING OUT FROM THE TAIL PIPE.
I BOUGHT A THERMAGASKET WHICH SAYS THAT IT WILL REPAIR THE GASKET THAT WAS DESTROYED WHEN IT OVERHEATED.IS THIS TRUE?
HOW DO I FLUSH THE RADIATOR ?
WHAT COULD BE THE PROBLEM OF MY CAR? THERE IS STILL POWER BUT PLENTY OF WHITE SMOKE COMING OUT FROM THE TAIL PIPE.
TNX
JOVEN

Answer
You blew the headgasket. Coolant is getting into the combustion chambers, burning, and exiting as white smoke.

You MUST replace the headgasket. Take the snake-oil back to the store you bought it from.  Also need to have the heads machined flat.

BMW's are great, but HATE overheating.