Through the heater core. I have a 66 and just switched to a reverse rotation water pump with serpentine conversion. Now my heater blows cold. It worked well before. Does the flow direction of the heater core matter. Im sure its a simple swap of the lines on the back but it is a bitch to get to so I thought i would ask first.

 

The heater core is just a little radiator and itself is not direction sensitive.

Just shooting from the hip I'd say that you have back-flushed the heater core and may have dislodged some goop & sludge and plugged it up. Maybe flush her out good and see what happens.

I have read that having the lines backwards can cause air pockets in the core and cause the heater not work as well.

 

I'm gonna flip the lines for ****s and giggles

 

I agree, the heater core should be non-directional.

I do wonder however if the direction of the thermostat (i.e which was the spring is facing) has anything to do with it now the the flow has been reversed. That's the only thing that comes to mind....

Please post what you eventually find that resolves the problem.

Good luck!

 

In theory you should place the incoming hot water hose on the inlet to the heater that has the temperature control on it. This way you don't have hot water entering into the heater core and dissipating heat inside the car during the summer when it is not being used. Just $.02 worth of info.

 

an even easier test, feel both heater hoses at the firewall for heat, that will tell you whats going on(or through).

 

i would think it does matter. you want the water to be pulled from the bottom of the radiator not the top where a pocket of would be. also as someone else said, the direction of flow into the thermostat matters. they are designed for flow in one direction.

 

does this help?. . .from another forum. http://www.mustangtech.com.au/Forums...c/p=77200.html

I recall this from the service manual, but don't have the manual handy. BTW, if its cold, you likely have an air pocket in the core.

 

Yes, Ford was very specific about this. The coolant should enter via the lower inlet, and exit the upper outlet. This avoids trapping air and sludge in the core.

 

So if I have a new engine with a reverse rotation water pump, should I plumb it backwards from the diagram