There is a heater hose connected to the intake, and another going to the water pump. Which one sends water to the heater core?

My '67 coupe has a valve in one of the lines. Its supposed to prevent hot water from flowing through the heater core when the A/C is on. I think it may be on the return line, but I'm not sure.

When I bought the car, the heater core was bypassed with the infamous Mustang Loop. Currently, it is connected to the hose that connects to the water pump.

 

The one from the pump should be the "pressure", the one in the manifold should be the "return",, if the valve is closing fully it should work equally as well in either hose, but, I have found that the heat tends to "migrate" up the pressure hose, and even more so when the cut offvalve is on the return... go figure..

 

its meant to stop water flowing regardless of a/c - that is no hot water when you dont want the heater on. Some heat will migrate up the hose, but if the heater box is closed it shouldnt matter. Theoretically it shouldnt matter which line the valve is on.

 

The A/C guy told me just the opposite. He said the manifold was the pressure side. He also suggested a manual (screw-down) valve to stop the flow of water into the heater core.

 

Correct, the water pump is a centrifugal type. Heater hose, and Radiator hose are on the input side, Engine block is on the output side (pressure). So, the intake manifold to heater core is pressure side, and heater core to pump is return.

 

That's the opposite of what JMDsaid.

 

I forgot to add my disclaimer,,,,
"I reserve the right to be wrong in any instance at any time.... without prior warning"

I had assumedwithout really thinking it through,,, I now invoke my reserved right....

 

Just put the hose that comes out of the thermostat on the top pipe of the heater box, and the hose coming out of the water pump on the bottom pipe of the heater box then you won't need to worry about all this theoretical crap.

 

There are several drawing, pictures and written instructions about heater hose hookups in Ford documentation showing both ways to hook up the hose. The most logical (from 'Mr. Spock on Fords') is from the water outlet to the bottom fitting and the top fitting to the intake manifold. This method allows any air in the hose and heater to go up into the engine then to the radiator. Theory, you bet. Now Uncle Glen, explain the theory of producing different notes on a slide t-bone by moving the slipstick up and down.
Jim

 

Neither hose comes from the thermostat. One is on the intake manifold, the other is on the water pump. Currently the valve is between the water pump and the heater core. Is that the supply side or the return side?

I completely understand that it doesn't matter which hose goes to which pipe of the heater core. But it DOES matter when you're trying toshut offthe flow of water into the heater core. The valve needs to be on the supply side hose, not on the return hose.

My A/C guy said I have my valve on the return side.



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