2000 chevy malibu keeps overheating. wont hold coolant. coolant boils out through overflow. and heater has stopped working

need to presurice the system to see the leak

replace thermostat.then bleed coolant system, this is how you do it.fill the cooling coolant system with 50 / 50 dexcool and water to raise boiling point,straight water will evaporate boil away cause engine to overheat catch fire thats why you need 50 / 50 mixture antifreeze and water.to bleed coolant system first fill coolant system until coolant stay at the full cold mark on the the coolant overflow jug,then you start engine allow it to idle,place the heater and ac control in any ac setting except max and the temperature control to the highest setting,run engine until lower hose to water pump is hot. with the engine hot run the engine speed up to 3000 rpm and allow it return to idle, repeat this 5 times. slowly open the bleed valve on the thermostat housing or look for bleed valve at the water pump heater hose.open bleed valve for 15 seconds to expel any trapped air.then top off the coolant as necessary,and when top radiator hose hot thermostat open up.keep adding cooling to overflow until coolant level stop at full cold mark dont over fill coolant.if engine seem like overheating while looking at cooling gauge turn off engine wait a while until cool off add more coolant until coolant level stay stable and dont drop any.when open radiator overflow cap use large rag over the radiator cap to keep from getting scald open radiator cap a little at a time but dont open radiator cap until engine cool down first.replace the radiator overflow cap, thermostat,and engine coolant temperature sensor and check the cooling fans fuses and relays see what happens.

Sounds like you need to disconnect the Radiators' electric fans and have them tested. You absolutely must have them working, or your car will overheat. Check to see if the Temperature guage is working.

You need to go to a good autoparts store and have them test the fans and charge and test your battery. You may need some sensors to activate the Radiator fans, but you could be running the battery down with shorted cooling fans.

There are also Relays which work with the Radiator fans. The overflow will stabilize once the water gets into where it belongs. Make sure your Thermostat is not clogged with the sealer.

you may have a faulty thermostat which stops the water from flowing through the engine causing it to boil which builds up extreme pressure forcing the water in the engine block back through the radiator into the overflow tank or it may be a faulty water pump which will do the same thing......hope this helps......cheers.

If I may ask, what color was the antifreeze that you took out of your car? If the coolant is not actually overheating, the coolant temperature sensor could be bad. Check the routing of the serpentine belt. It is possible to get the belt on wrong and turn the water pump in the wrong direction, which would cause overheating because the coolant would not be circulating as it should. That would also prevent the heater from working since the coolant would not be flowing through the heater core.

CHECK COOLANT LEVEL STILL LOW.ADD MORE COOLANT.UNTIL RADIATOR OVERFLOW FULL AT COLD MARK.THEN CRANK ENGINE UP LET IDLE FEW MINUTES LOOK DOWN COOLANT OVER FLOW JUG ADD MORE COOLANT IF LEVEL DROPPED.WHILE ENGINE RUNNING KEEP EYE ON TEMPERATURE GAUGE.WHEN THERMOSTAT HOSE GET HOT.TURN OFF ENGINE WAIT A LITTLE WHILE TO KEEP FROM GETTING SCALD TAKE LARGE RAG PLACE OVER OVERFLOW JUG RADIATOR CAP.OPEN CAP A LITTLE A TIME.IF COOLANT TRIES BOIL OUT.LET VECHICLE SET A WHILE LONGER.ADD MORE COOLANT.WHEN COOLANT LEVEL CORRECT AND ALL AIR OUT THE COOLANT SYSTEM.IT WILL STOP OVERHEATING.LONG AS ENGINE RUNNING HOT TURN OFF THE ENGINE POUR IN MORE COOLANT UNTIL COOLANT LEVEL STOP DROPPING IN RADIATOR.KEEP COOLANT LEVEL IN OVERFLOW AT COLD MARK.DONT OVER FILL OVERFLOW JUG.

You may have a radiator leak. Or your coolant level is low. Using the heater is not a solution to an overheating vehicle. You can usually smell coolant and see the leak. Often times a gasket can leak mixing engine oil and coolant, decreasing effectiveness of both sytems. Check color of fluids make sure the cooloant is viscus and not sludgy.

Also check coolant fan electric connections and fuses. The fan really cools down the engine moreso than coolant. It should kick on when your engine reaches a certain temp. If it does not the vehicle will overheat.

I hate to tell you this but it sounds like a blown head gasket.

The year of the vehicle, rusty liquid, and overheating, says your radiator could use a replacement. If it was your water pump, you would have liquid coming out of the water pump itself.

The overheating will not have anything to do with the lost of power for cranking or the lights not working. Try charging the Battery and start over.