Since it's been getting a little warmer around these parts I've noticed that my car has also been running a little warmer, and a little warmer, and now just plain hot. Something is definitely wrong with my cooling system and I think it is the heater core. This is why I think a problem with the heater core is to blame: I was coming home from work and my car was beginning to warm up, as it reached operating temperature it continued to climb dangerously high on the stock temp gauge. Here is the key to my story, I turned on the heater to hopefully draw out some of the heat but I felt no heat through the vents. I kept turning it on and off until I finally felt a blast of heat through the vents. The wierd part is, as soon as heat came through the vents the engine temperature began to drop. It continued to run fine until I got home and was letting it idle. At idle, the temperature began to rise again, and the heat coming out of my vents once again turned cold; kind of like there was not enough pressure at idle to push coolant through the heater core.

Before you draw your conclusions there is a few things you should know, I have a rebuilt engine with about 10,000 miles on it, I have a new radiator and my hoses are fairly new, I just replaced my thermostat no more than a week ago with a Mazda genuine thermostat, all other parts of the cooling system seem functional.

So what do you think? Is my heater core clogged? I just thought it is wierd how my engine temperature is congurent with the amount of heat coming out of the dashboard vents.

thanks for your suggestions,
-kev

 

bump

 

B

 

No help huh? Well that's alright, I warmed her up today and felt the inlet heater hose and the outlet heater hose, guess what, inlet=hot, outlet=cold. Heater core has to be clogged. I'm gonna bypass it for now just to make sure that is the problem: Good thing it's not winter.

 

have yo tried a flush yet? I used zerex coolant flush on my car.

 

Let's bring this one back. I have this problem at idle, if I rev the engine the vent air starts to heat up but at idle its just cold. Anyone have any insite, experience and logic are both welcome.

 

So you still have the original problem?

The heater core is not causing your overheating. The heater is in parallel with the radiator, so if it's blocked the cooling system still has full flow.

The reason the engine temp dropped when the heater started working is because the heater is acting like a second radiator, increasing the cooling system's ability to reject heat.

It sounds like you have a Logicon problem that is causing intermittent opening of the heater water valve.

The cooling system should not need the heater on to work properly. If you overheat with the heater off but it cools down with it on then you do have a cooling system problem, but it's not the heater.

Cheack all the usual things: thermostat, radiator, belts, water pump, coolant condition, air in system, etc...