Eclipse heating issue

As you all know, my eclipse is acting up again. Its blowing a high amount of air out the vents, but its luke warm at best. I just replaced the thermostat and housing, and im doing the coolant temp sensor, and the coolant temp sender tomorrow. She also likes to overheat every now and then. Not like, blowing coolant gas everywhere, but she likes to spike the temp up every now and then. What do you think could cause this?

Coolant systems are quite simple, unfortunately Mitsubishi had to make them more complicated than need be.

But regardless, heat temp is controlled by one thing only, the thermostat. so if you have a issue you want to start there, but you replaced it so you should be good. If your not getting good heat after you replaced it... 1. did you replace with a 180-190 degree or did you use a lower temp... and two did you use the rubber seal that goes around the thermostat? on the 4G63 you can not put that in and the system won't leak, but coolant will just blow by the thermostat and not get a chance to come up to full temperature.

As for the temp spikes, check your heat at the time to see if it's hot or not? if it doesn't seem to be getting hot, it could just be a bad temp sensor.

Also keep in mind, those nice pretty headers you just put on may be cooking your radiator....

You have an airpocket Joe. It takes a bit of patience to purge those engines. Get it on jackstands when it is cold. Fill it up, warm it up, let it cool down to the point you can remove the radiator cap, then fill it and start it, have someone rev it while you are under the hood with more coolant mixed with HOT water and fill it while it is revved up, replace the cap and let it self perge, check the level and fill again and you should be fine. The spikes are from the airpocket going by the sensor. Steam is a LOT hotter than liquid.

i would say the same thing air pockets are a sob to get rid of and usually it shows up with the problems you have.

i thought it might be the water pump. Crossing my fingers that its not

If it were overheating steadily, I would be more prone to point you in that direction. Also, if it were overheating steadily, you could have put the thermostat in backwards. But where you mentioned it just spiking off from time to time, that tends to make me think air. Now if you do this and it still doesnt blow out heat and overheats, then I have bad news for you with that pump.

did you add or loose coolant recently?

I installed the coolant temp and coolant sender yesterday. Seems to be keeping the temp normal, but still no heat!

Air pocket prolly in your heater core pump and burp with the car off and cool

With those cars, you want to purge the system with the nose in the air so that the absolute highest point is fill cap. Air runs uphill but there are 2 natural high spots so getting the air through them without the nose up is an absolute pita.

On a sidenote, if you find your system is full and showing normal temp, make sure the diverter flap on your heater-box is actually opening and closing when you turn the temp from hot to cold to hot. If that isnt working, then you may have caught a vacuum line under the hood or dash.

ohh good call, I forgot about that, DSM's are famous for the flaps breaking, my air/exchange cable is stuck on the spyder...

Yeah it just popped into my head because that is a common problem for most manufacturers.

Did you ever figure it out Joe?

i figured out the overheating. it was just the sensors. now i need to figure out the low heat problem. probably the water pump.

no cause if your water pump was failing, you'd over heat... plain and simple, either your pump works or it doesn't... So I would look at your Thermostat (make sure it has a seal around it and water isn't just blowing bye it and not getting up to opporating temp, and that the ducts are working properly... don't forget that DSM's are not good heat producers as well... other thing to check is the feed and return lines to your heater core, make sure that it's hot going in and hot coming out... (heater core is just a small radiator... )

I should have tomorrow (friday) off Joe, if you want to come up to Warwick I'll help you go threw it and figure it out...

Yeah, just hope it isnt the heater core. There goes the better part of your afternoon/evening.

Sorry man, i didnt have a computer for a few days.

Thats cool, you get her figured out?