2001 malibu wont blow out heat on a continuous basis, flushed system, replaced thermostat twice, last one i put in a 180, coolant must be leaking because we have to top it off, after bleeding we have heat for couple days then go back to cold air and motor run hot, cold the raditor be cloged?

get a new radiator

Sounds like you need to have the cooling system flushed out then have them put a new themostat in it. If that dont fix the prob you might have to put a new heater core in it or radiator.

What about the coolant temperature sensor or water pump?

did it over heat be for he change the gasket? if os i would be kooking at a head gasket is out

The radiator might be clogged. Take it and have the system flushed out,and back flushed, that will tell if there is a clog somewhere. If the radiator is too clogged, it will need to be replaced.

Due to the complexity of the newer cars on the raod today!! what you are experiencing is Normal!!! since the coolant systems on the newer cars run at such a higher pressure and a high Rpm the reserve tank which has it's on drain hose for excessive overflow from the radiator allows the extra high pressure release from the radiator to back flow to the reserve tank and then out the reserve tank overflow hose on to the raod

is electric radiator fan coming on? if not the relay or fuse is bad

I would recommend flushing the cooling system and replacing the thermostat.....easy to do and only about $14 for a new thermostat.If that does not work then you either have a coolant leak somewhere or a bad heater core. I would also pressure test your cooling system before you flush the system to look for leaks in the system

First think to check is the coolant level. If your Malibu is a 2001 you have the 3.1 engine that has problems with the intake manifold gasket leaking coolant. When the coolant level gets too low the first thing that is affected is the heater.

a bad heater core will just leak. it could leak alot. do you ever smell antifreeze? check the coolant level. it can get pretty low before it will overheat. the thermostat should be ok but there could be corrosion. when you had the water pump replaced was the cooling system flushed? 2001, its probably due for a flush. what coolant does it take? (green or orange)