My 1999 alero is overheating and engine coolant is leaking

Well, I hate to break this to you but your coolant is leaving through your exhaust pipe. You may have a bad head gasket or your engine block may be cracked. Coolant is leaking into the cylinders and burning off when the engine fires and exiting through the exhaust.

Well, that's a good engine test, anyway, not smoking and blown up yet, lol. I like your attitude, are you sure you don't drive a cavalier?
It sounds like the water pump, Molly. Better get it changed before serious damage results.

CHECK HEATER PIPE OR HEATER HOSE AND CHECK COOLANT INLET PIPE FROM THE THERMOSTAT HOUSING. CHECK HEATER OUTLET HOSE FROM THE RADIATOR OUTLET PIPE.SOUND LIKE COOLANT LEAK COMING OFF TOP OF ENGINE.

OVERHEATING CAN BE CAUSE BY MANY THINGS LIKE FAULTY THERMOSTAT AND FAULTY RADIATOR PRESSURE CAP,TOO MUCH WATER IN COOLANT SYSTEM NEED 50 / 50 WATER AND ANTIFREEZE.LOOK FOR WATER PUMP WEEP HOLE LEAK, IF COOLANT LEAKING OUT WEEP HOLE WATER PUMP BAD NEED REPLACING.CHECK FOR LOW COOLANT LEVEL, YOUR RADIATOR OVERFLOW JUG SHOULD HAVE COOLANT AT THE FULL COLD MARK IF NOT KEEP ADDING COOLANT INTO COOLANT OVERFLOW JUG UNTIL COOLANT STOP DROPPING AND FULL COLD MARK, IF OVERFLOW COOLANT JUG WAS EMPTY RADIATOR IS LOW ON COOLANT.WHICH CAUSE AIR IN COOLANT SYSTEM KEEPING THE ENGINE COOLANT TEMPERATURE SENSOR FROM BEING SUBMERGE IN HOT COOLANT WHICH TURN ON THE COOLANT FANS.WHEN ENGINE COOLANT TEMPERATURE GET CERTAIN SET TEMPERATURE LIKE 190 DEGREES THE PCM AND COOLANT SENSOR WILL TURN ON COOLANT FANS, IF VECHICLE OVERHEATING COOLANT FANS NOT WORKING EITHER YOU HAVE FAULTY ENGINE COOLANT TEMPERATURE SENSOR CHECK COOLANT FANS FUSE AND RELAYS. YOU CAN CODE SCAN CAR TO SEE IF YOU HAVE FAULTY PCM, FAULTY ENGINE COOLANT TEMPERATURE SENSOR OR FAULTY COOLANT FAN RELAY.IF COOLANT FAN AND ENGINE COOLANT TEMPERATURE SENSOR OKAY,YOU HAVE CORRECT COOLANT LEVEL IN COOLANT SYSTEM, THERMOSTAT AND RADIATOR PRESSURE CAP BEEN REPLACED, YOU COULD HAVE BLOWN HEAD GASKET CHECK ENGINE OIL LOOKS LIKE MILK SHAKE HEAD GASKET BLOWED ALSO WHEN HEAD GASKET BLOWED YOU CAN DRIVE CAR SHORT DISTANCE START OVERHEATING AND YOU LOOSE ENGINE POWER SUSPECT BLOWED HEAD GASKET.

CAR OVERHEATING FIRST CHECK FOR LOW COOLANT IN THE RADIATOR COOLANT OVERFLOW JUG.IF COOLANT LEVEL IN OVERFLOW JUG LOW REFILL ADD COOLANT BACK TO THE FULL COLD MARK.PUT RADAITOR CAP ON COOLANT OVERFLOW JUG START ENGINE LET IT IDLE UNTIL IT OPERATING TEMPERATURE.MAKE SURE TOP RADIATOR HOSE GETTING HOT WHILE ENGINE WARM UP.IF TOP RADIATOR HOSE DONT GET HOT WHILE ENGINE IDLING YOUR THERMOSTAT COULD BE STUCK CLOSE CAUSING CAR TO OVERHEAT.IF TOP HOSE IS GETTING HOT.CHECK FOR COOLANT LEAKS CHECK TOP RADIATOR HOSE AND BOTTOM RADIATOR HOSE FOR LEAKS.CHECK FOR LEAKS AT THE RADIATOR CORES AND PLASTIC SIDE CONTAINERS.IF ALL IS GOOD ENGINE OVERHEATING WHILE IN A LONG TRAFFIC LINE, COOLANT FANS NOT COMING ON.COULD HAVE FAULTY ENGINE COOLANT TEMPERATURE SENSOR OR BLOWN COOLING FAN FUSE OR RELAY.COULD HAVE PCM FAULT.MAKE COOLING FAN ELECTRICAL CONNECTORS AND WIRING NOT DAMAGE OR BROKEN.

CHECK FOR COOLANT LEAKS AROUND THE RADIATOR LOOK DOWN BETWEEN COOLING FANS AND RADIATOR SIDES FOR SIGNS OF ANTIFREEZE.CHECK ALL RADIATORS HOSES AND HEATER HOSES.IF ALL LOOK GOOD CHECK ENGINE OIL FOR COOLANT LEAKS.IF OIL LOOKS LIKE MILK SHAKE COOLANT LEAKING IN CRANK CASE.YOU HAVE A HEAD GASKET LEAK.YOU NEED TO CHANGE OIL + FILTER. GET THE HEAD GASKET FIX.BECAUSE LEAK IN THE CRANK CASE WILL LOCK UP THE ENGINE.IF CRANK CASE OIL LOOKS OKAY.YOU DONT HAVE THE COOLANT CORRECT MIXTURE.YOU SHOULD HAVE 50/50 ANTIFREEZE AND WATER.

not a complete history in your brief 'sentence', but water from the exhaust is either condensation whick is normal, or you have a blown head gasket or worse (cracked head or block) which is going to be very expensive to fix. If it is not overheating too, you have nothing to worry about, if it is you need to get the car to someone who can do a compression test and cylinder and/or coolant leakdown test to determine the extent of the damage.

SOUND LIKE ENGINE COOLANT FANS NOT RUNNING.CHECK TO SEE IF COOLANT FANS RUNNING WHEN ENGINE START OVERHEATING.IF NO CHECK COOLANT FANS FUSE AND RELAYS.IF ALL IS GOOD.HOTWIRE COOLANT FANS TO MAKE SURE THEY ARE WORKING.IF NO REPLACE FAN MOTOR.IF FAN RUN WHEN YOU HOT WIRE IT.THE COOLANT TEMPERATURE SENSOR FAULTY ARE THE PCM FAULTY YOU CAN USE A SCANNER TO CHECK THEM FOR FAULT CODE.IF EVERYTHING GOOD SO FAR.REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP FLUSH ENGINE BLOCK AND RADIATOR.CHECK RADIATOR AND CONDENSOR AIR CORES MAKE THEY NOT STOPPED UP WITH LEAVES AND OTHER DEBRIS THAT WILL BLOCK OFF AIR FLOW THROUGH THE FRONT GRILLE RADIATOR CORES.ALSO CHECK WATER PUMP WEEP HOLE IF ITS LEAKING WATER PUMP NEEDS REPLACING.

it is the coolant level sensor that is making the light come on, your car does not have to be overheating for it to come on.
once the coolant level goes below the sensor it turns the light on.
If you fix the leak it will stop the light going on unless the sensor is faulty.
Hope this has helped.

check the entire engine freeze plugs hoses radiator . check engine oil .if look like milk shake you got a blown head gasket. if it dont burn oil dont smoke . fix the leak . if it got 150000 or more . cost to much to fix buy another engine.