Spent the winter going through the car..replaced water pump, all belts, hoses, thermostat, etc..not because it was overheating to start with but because car had been sitting a while and I wanted something to do while I drank beer with friends. Well, now car is back together but things don't seem quite right. For starters, I have no heat. As stated, the thermostat is new and I can see the water circulating in the radiator. Temperature is running around 220 with a 180 thermostat in it...a little warm. Car had heat and no overheat conditions before I got into it.

I'm wondering about the hoses going to the heater core. Could they possibly be reversed? How would the car act if they were? I noticed the hose going from the core to the pump was hot towards the engine but cool to the heater core. Also, no leaks from the core inside the car and any other obvious signs of heater core failure.

Could somone verify the hose proper hose routing from the inner and outer heater core nipples? Any other ideas on what to check? I have no obvious leaks and the radiator is full and circulation but car is running too hot and I have no heat..thanks.

 

there may be a valve on the back passenger side of the intake where the heater hose from the heater core goes. if your car has this valve, it may be defective or the vacuum line going to it may be bad. i think this vacuum line comes from under the dash. i would check the valve first. and then check to see that you have vacuum at this valve when the heater is on. when the heater is off you should not have vacuum.

 

Scott, what year is your car? At some point, the heater valve was changed to a normally open design (open without vacuum applied) to make the heater more failsafe. The 72 and 86 is this way. Of course if you do not have factory AC, then the valve may not even be there - just one hose from the water pump, the other to the rear of the block.
If this does not help, disconnect the two heater hoses and run a low pressure garden hose through the heater core to see if it is blocked with crud...

 

thanks for the correction.

 

It's a 72 with ac.

 

Scott, hose from pump to top right nipple(if you are looking at it), the nipple closest to right fender to valve...my car is a '72 w/AC!

 

Aren't those hoses also different sizes?? 5/8 and 3/4??

 

Oui, oui !

 

yeah, that would have been pretty dumb to reverse those hoses but I never claimed to be perfect...anyway, they check out so I guess I'm looking at either the core itself or the control valve. I think I'll try and flush it out first as Rob suggested...thanks.

 

Is the 3/4" heater hose going to the water pump look kinked? That is a tight bend for straight hose... If not, proceed with the below...

If the core is clear, LIGHTLY force some water in the 3/4" heater hose going to the water pump and water should easily flow out of the 5/8" one coming from the heater valve (engine off of course.)
If not, then the heater valve is blocked or frozen closed. Pull the valve and repeat the above. Water should now flow out of the block easily.