Just replaced my thermostat, water pump and I still have a coolant leak looks like coming from radiator. Not overheating but smoking from coolant hitting the motor.

A worn water pump is the most likely. If the coolant is going down, the water is going somewhere.

The most common reasons an Oldsmobile Alero is overheating are a coolant leak (water pump, radiator, hose etc.), the radiator fan, or a failed thermostat. Coolant leak (water pump, radiator, hose etc.)

Oldsmobile Alero Overheating - RepairPal

Videos on overheating. You probably have air in the system from when you replaced the thermostat. The coolant system needs 'burping' of air.

https://www.google.com/search?q=2000+Oldsmobile+Alero+running+ho

Burping

https://www.google.com/search?q=burping+coolant+system

..

overheating sound like faulty thermostat.thermostat either sticking close or could have blown headgasket if you see a lot of white smoke coming out of exhaust.if headgasket is leaking check engine oil should look milky.also check water pump look around weep hole or see coolant leaking around water pump replace water pump.also check water pump drive belt.make sure drive belt not loose slipping.

REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP.IF CAR OVER HEATING WHILE IN MOTION.MORE LIKELY ITS THE THERMOSTAT,LOW COOLANT IN RADIATOR OR COOLANT SYSTEM,BAD WATER PUMP,WATER PUMP WEEP HOLE IS LEAKING, WATER PUMP NEEDS REPLACING.CHECK ENGINE OIL,IF OIL LOOKS LIKE MILK SHAKE YOU HAVE LEAKING HEAD GASKET.IF CAR IN PARK AND OVER HEATS WHILE IN A LONG TRAFFIC LINE OR.BANK DRIVE THROUGH COOLANT FAN NOT TURNING ON, BECAUSE THE ENGINE COOLANT TEMPERATURE SENSOR FAULTY.CODE SCAN CAR FOR FAULTY COOLANT FAN RELAY OR FAULTY PCM. CHECK COOLANT FAN FUSE, AND HOT WIRE THE COOLANT FAN TO MAKE SURE ITS WORKING.IF COOLANT FAN DONT WORK WHEN HOT WIRED. COOLANT FAN NEEDS REPLACING. REPLACE BOTH RADIATOR HOSES, REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP.BUY NEW COOLANT ADD 50/50 WATER AND COOLANT.IF ENGINE OIL HAS ANTIFREEZE IN IT.REPLACE ENGINE OIL AND OIL FILTER TO KEEP FROM LOCKING UP THE ENGINE.GET CAR FIX.DONT KEEP DRIVING IF IT KEEP OVER HEATING,ENGINE DAMAGE WILL OCCUR.I HOPE INFORMATION I GAVE YOU WILL FIX PROBLEM.PROBLEM COULD BE LEAKING RADIATOR HOSES BUT CHANGE THERMOSTAT THATS FIRST THING I WOULD CHANGE BECAUSE IF IT CLOSED, ENGINE WILL OVER HEAT AND CRACK CYLINDER HEAD OR CRACK PISTON, COOLANT NEED TO CIRCULATE THROUGH THE ENGINE TO TAKE AWAY THE HEAT FROM ENGINE.

SMOKE UNDER HOOD COULD BE COOLANT LEAK FROM RADIATOR ITSELF OR CHECK FOR LEAKING TOP RADIATOR HOSE AND CHECK FOR LEAKING BOTTOM RADIATOR HOSE.LOOK UNDER THE HOOD IF COOLANT BOILING OUT COOLANT OVERFLOW JUG ENGINE OVERHEATING FROM BAD THERMOSTAT OR BAD WATER PUMP.CHECK FOR COOLANT LEAK AT WATER PUMP WEEP HOLE.IF SO WATER PUMP NEED REPLACING.ADD MORE COOLANT UNTIL LEVEL CORRECT.TRY LOCATE LEAK. IF CAR OVERHEATED AND BOILED IT OUT. SMOKE UNDER THE HOOD CAN ALSO BE CAUSED BY LEAKING VALVE COVERS WHICH CAN BE FIRE HAZARD IF OIL LEAKS ON HOT EXHAUST MANIFOLD.

Now that you've eliminated the thermostat, it could be a number of other things. Don't drive the car too far until you've fixed the overheating problem - overheating can destroy an engine.

That split ribbed hose you see is plastic wire loom - it carries and protects electrical wires, and is not the cause of overheating.

1. Low coolant level
2. Radiator hose split/cracked, causing low coolant level.
3. Head Gasket - leaking, causing low coolant level
4. Thermostat - stuck closed (you eliminated this possibility)
5. Radiator cap - worn/damaged
6. Radiator fins - obstructed by debris/cardboard
7. Water Pump belt - missing/broken
8. Heater Core - leaking, causing low coolant level
9. Intake Manifold Gasket - leaking, worn, damaged
10. Radiator Fan Relay - faulty
11. Radiator Fan Blade - broken, missing
12. Radiator Fan Sensor/Switch - faulty
13. Water Pump - leaking, causing low coolant level
14. Radiator Fan Motor - faulty

My primary suspects would be Rad Fan Relay (#10), and
Rad Fan Switch (#12).

If water poured out you probably busted a hose or radiator sprung a leak. Sounds like that and a bad thermostat or water pump went out.

make sure your over flow/add coolant bottle is clean...check that the hose from bottle to radiator isnt clogged...also fill add bottle fluid level between add and full mark

hard to get to and difficult job...are you sure you dont have cracked head? is there water in the oil....does the oil look milky? look in the radiator is there oil residue in the coolant........

First, plastic tube may be the overflow vent from the coolant bottle.Check to see where the attached end goes. You are going to have to check engine for coolant leaks (carefully refill system without spilling anything, then look for dripping anywhere. Look for leaks from all hoses, fittings radiator, water pump etc) After checking for leaks, start it up and check again (watch where you put your hands though) While running, check that the fan comes on when the vehicle reaches operating temp.(no fan, check fan motor, sensor & relay) Turn the heat on (does it have heat?) Check temp of lower hose and upper hose. If overheat happens, is lower hose still cold? (likely bad thermostat). If you found a leak, replace whatever is leaking...best insurance is to change thermostat after any overheat. Last, is there any white smoke from tailpipe, does engine run rough? If so, could be a failed head gasket or crack in cylinder head. (at this point last thing to worry about unless there is excessive smoke or rough run or oil in radiator or coolant in oil).

Good Day,

White some indicated that coolant is burning off. It could just be a simple leak which is burning off of the hot motor. It could also be a bad head gasket(probably what you don't wanna hear), One indication that it is the head gasket is white smoke coming out of the exhaust, this happens as coolant gets into the oil and is burned off then exhausted out the back. Possible causes for the overheating include, low coolant, coolant leak, thermostat, water pump and or water pump belt, or head gasket.

If I were you I would drain and flush the radiator, then fill it with new coolant, and change the thermostat, provided you have no white smoke coming out the exhaust.

hope this helps for now