Overheating mitsubishi galant 2001

check thermostat and replace if deffective. easy way to check is start car after a few minutes check upper and lower hose for equal temp. if upper is much cooler than lower hose change thermostat

Are your cooling fans operating?

Check the water pump.

There is probably some kind of damper that opens and closes under the dash that allows the air from the blower to be blow across the heater core under the dash. Sometimes these are controlled electronically or by vacuum tubes. Look underneath the dash and look for small vacuum hoses that might be dangling loose or possible little wire cables that might have come off the sides.
Possibly check Haynes Manuals (www.haynes.com) to learn how to change a Heater Control Valve.

Assuming the following;
The head gaskets were replaced properly
The Water Pump was replaced properly
The Thermostat was replaced properly

There are only a few other things to check.
1) if you you remove one of the heater hoses from the engine bib during a cold filling from the radiator - it will release trapped air until you see the coolant coming out the motor side - this works great to ensure the air is out. Hook hose back up before running.(or you could leave the hose off for a second and start it to see if water gushes out - water pump check - kinda messy though)

Remember that heater water will circulate even with the thermostat is closed.

if that does not work, then you need to ensure the top hose going to the radiator warms up indicating the thermostat is opening and hot engine water is starting to dump into the radiator.

2) the radiator more than likely is clogged and needs cleaning by a radiator shop, or replacement if it is not one that can be cleaned.

Ask your son if he remembers looking into the water ports where he took off the old water pump, sometimes of the system is not flushed at proper intervals, it will sludge up the water jackets and keep water from circulating through the motor.

one last thing (gulp) That CO check is pretty accurate - and cheap. You might want to have it checked again - because the heads should have been inspected for cracks as well as pressure checked before putting them back on - especially since the motor overheated. That alone will crack the heads beyond repair - more so than not.

Let me know if you have any other questions.

Good Luck.

just follow the top radiator hose to where it attaches to the engine. There should be a housing held to the engine by 3 bolts. On the v6 it's much easier to access if you remove the battery and the battery shelf before you start.

You could have a couple of issues.
Heater core
Radiator blockage

You should not drive the car to avoid overheating the motor. Have the system checked by a mechanic. You could simply have air lock.

Youfr front end is either wheel balance if your steering wheel shimmies side to side or if it shakes up and down it may be alignment. Neither is good for your tires, Try the balance first (cheapest fix)

clogged with old rad chunks
no white smoke

There is an electric motor that turns heater core on and off. It's located under the dash to the left of the glove box. Some disassembly required. The part will cost about $120 to $180. part number is #MR958603.

before u add water in ur radiator make sure u start ur engine and remove ur radiator cap and pour water to it when u see there is no more air in ur radiator u can close it and it will work good