2000 malibu overheating, no heat?

Question

I have a 2000 malibu, and have replaced the head gaskets, lower and upper intake manifolds, and thermostat. After running about an hour, the temperature goes all the way up. I also have no heat coming out of the heater, and the system seems to be overpressurizing. Does any one have any ideas what this can be? I have heard that it could be a faulty radiator cap. Any ideas would be greatly appreciated.

yes, I used the bleed screw on the valve located on the pipe on the front of the engine. Forgot what the name of the pipe is, buit it has a needle type valve on it. When loosened, get water coming out, not air.

Answer 1

check and see if your heater hoses are collapsing which would explain no heat and and to much pressure.A rad. cap would cause pressure release not to much pressure.If the heater core is plugged it will stop your car from getting any heat ,but once again if the hoses are collapsed that will stop coolant from getting to the core and causing no heat.

Answer 2

When the engine gets hot is the water circulating in the radiator? If not the thermostat is stuck .
No coolant thru the heater hoses could be caused by numerous things, No coolant, bad heater control valve, water pump not pumping, bad heater control switch, heater hoses plugged off, heater core by-passed. Are you getting good air flow thru the radiator?

Answer 3

sure sounds like air,everytime i read,what you wrote.ok, try this,warm up the car and take 1 of the hoses off the heater core,to get air out of it,thats the way i do it.and did you flush out the cooling system?you could have a dirty heater core.also once the engine is hot,shut it down and feel the radiator fins,on the side of the fan,to see if theres any cold spots.if there is,then the radiator needs flushing.

Answer 4

i would first check to see if there is coolant in it...explains the lack of heat when heater is on and overheating. then check the thermostat if it is not opening up then the coolant in the reservoir is not getting put in to circulation. That could cause it to over heat. i have never heard of the radiator cap causing problems but hey they are cheep so if the other two fail why not change it out. good luck

Answer 5

Try flushing out the entire cooling system. Run fresh water one direction then flush it in the other direction. A faulty heater core could be the cause of no heat or it could be full of crap and clogged.

Answer 6

is it a 3.1 engine? did you "burp" the cooling system when you changed the stat? - when changing a stat on a 3.1 you have to run the motor with the cap off for a period of time and it will burp an air pocket out of the system that prevents circulation of the coolant

Answer 7

Your motor vehicle develop into over heating with out the a/c on(?) yet ran cool with a/c on.in the adventure that your motor vehicle has duel followers,the a/c cooling fan develop into conserving the radiator cool.You replaced the fan relays yet did you have the water warmth sensor checked or replaced.this is assuming the two followers artwork while checked with a jumper twine from fan(s) to battery.achievable you have a loose connection to water/coolant sensor if sensor tests out as cool. confusing to tell without looking under hood yet i could examine those besides as changing radiator cap (affordable restore).All hoses look into in sturdy shape?

Answer 8

did properly blead the air from the cooling system?

Answer 9

sure sounds like air in system,did you use the "bleeder"screws?