kind of a newbie here,
I have an 03 evo 8 that does not get hot or warm ever. the temp gauge will go up when I am stopped at idle but when I start moving again it drops even down past the C. I replaced the rad, thermostat, and even ran a piece of carboard infront of rad, and it just never even gets up to a proper operating temperature. on top of that I never have heat in the car.anyone ever heard of this?

 

But have you tried replacing the temp gauge?

Or air is still in the system!

 

I haven't replaced temp gauge judging that I think its accurate based on my lack of heat inside the car and how it always runs when its cold.(motor flutters under boost)

 

Or did you replace the temp sensor? Was the cooling system properly burped?

 

Sounds like you have air in the system from the fact that you're not getting heat in the cab. What you need to figure out is where the air is coming from. If you recently emptied and filled your coolant the system may not have been properly burped. But if you haven't touched the system I would check your coolant for oil and oil for coolant which would indicate a bad head gasket. Otherwise you may have a leak in the system letting coolant out and air in.

 

That is assuming your blender door is working properly and switching to let hot air in, I would check to make sure the door moves when you change from cold air to hot air. If that isn't moving it may be as simple as the blender door isn't selecting hot air and your coolant sensor isn't working.

 

there is no leaks or air pockets, I properly burped the system. the car will increase in temperature when at idle or on a warm day. when im driving in the cold the temp drops down to cold. you can feel it in the heat from being at a stop and it gets warm, to when you get on the highway and its freezing cold.

 

about 8 months ago I changed the cable and gears for the blender and I got underneath to verify that the door is in the position for heat only.

 

When your gauge is reading increased temps, have you tried to see if you get warm air then?

 

yes and that is when I am getting warm air.

 

Let the car warm up to operating temp, once it's there feel the upper and lower radiator hose and the upper and lower heater core hoses, if there is a large temp difference this will help to locate the source of the issue. Also measure the temperature of the air coming out of the vents when the heat is on full blast. Also how cold is it when you're driving and having issues and what mixture is your coolant at.