Ok, I'm having some overheating issues and yesterday morning my heater stopped blowing hot air. I'm pretty sure it's the heater core. Where is the heater core and how hard is it to replace?

 

Heater core is inside the dash. You must remove the dash board in order to get to it which will most likely take a while, labeling things and just figuring out how to get it out. I would get a Hayes manual or something before attempting it.

If you're having overheating problems though, you could be loosing coolant. Have you checked your coolant (via radiator cap)? or replaced anything? Also, what year is your Neon?

 

1st thing check coolant level
2nd thing check rad for obstrutions(bent mashed up fins)
3rd thing check for waterpump flow
4th thing check for T-stat failed in closed position
5th thing check for head gasket failure

if you dont have a greasy film on inside of windscreen , cant smell coolant, or floor boards are dry I'd bet your heater core is fine Im thinking one of the checks above will expose the culprit

and since its such a treat to change I recomend your positive its shot before you go about changing it

 

1st thing check coolant level
I keep losing coolant
2nd thing check rad for obstrutions(bent mashed up fins)
Radiator is fine
3rd thing check for waterpump flow
Checking....
4th thing check for T-stat failed in closed position
Checking as well....
5th thing check for head gasket failure
Head gasket is fine, no water/coolant in the oil

 

wheres the coolant going?
you see puddles on ground or is it leaking into car?

 

that's a mystery to me...no noticeable puddles on the ground and no indication that it is in the engine. Not smelling it inside the car, no oily film on the windshield or anything either. Boiling the t-stat right now seeing if it opens.

 

ok, thermostat seems to be stuck closed. I didn't notice anything obvious that it opened when I boiled it. What exactly am I looking for when it is supposed to open?

 

there will be a rating stamped into the stat, when the water boils at the rating you will be able to see through around the inside

http://www.youtube.com/watch?v=kZLJB...eature=related

 

It maybe a head gasket but try replacing the radiator cap first then suspect the headgasket. I know it sounds weird that it would be the cap but there were a few folks that complained about the same thing and also they said they heard a bubbling noise from the enging when they turned it off. But the bubbleing noise what because of a head gasket issue

 

if your heatercore is losing coolant you should smelll it since its inside the car. if its not blowing air, then its your fan. you could try and use a uv dye in your radiator fluid then check with a black light. also heater core is a pain but i was able to only half remove the dash and replace it. saved alot of time