Need help with heater hose and control valve install

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Joined
Jan 20, 2022
Messages
1,123
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Location
Homer Glen, Il
My Car
1971 Mustang Mach 1 351c FMX trans and 9 inch rear end
Hi All,

First off, I'm sorry I originally posted this thread in the concourse section.

I am starting the install on the heater hoses and I have a few questions (here is where my lack of Ford experience kicks in). I realized that I do not know the flow pattern between the heater core and the water pump and block ports. Also, I am trying to buy a heater control valve and NPD has one without a bracket and has arrows indicating the flow can go in either direction for this valve. Unfortunately, this valve has been out of stock for the last month and they told me on the phone they do not know when they will get more in stock. CJ Pony (not my first choice for suppliers) has one but there is only one arrow cast in the case of it which seems to indicate the flow can only go one way, and this valve has a mounting bracket. Can someone please tell me which style of valve is correct for my 71 Mach 1 351C with A/C? If it is the style that NPD offers, does anyone know where I can get that style without waiting for NPD to get it back in stock?

Hemi Killer posted a great diagram (see attached) of the routing in a different post I found on heater hose routing which was very helpful in the routing aspect, but the drawing overlaps the two hoses as they run along the intake manifold. I am unable to determine for sure which hose is which from the engine end to the heater core end. It appears to me that the water pump outlet hose is the one that has the control valve in it and it is attached to the inboard port of the heater core and the hose attached to the outboard port of the heater core runs directly to the nipple in the block, is this correct? If it is, am I correct in assuming the flow runs from the water pump through the control valve and on to the heater core and then returns to the block? If this is the correct flow pattern then it appears that the CJ Pony valve's one way flow is backward to the bracket orientation. Where the bracket could be mounted on the intake the flow arrow points the opposite direction. It does look like the valve and bracket could be swapped around to work though. I appreciate any help I can get regarding the flow and the correct valve style and if anyone has used either of these valves themselves. Thank you

Mach 1 468.jpgMach 1 470.jpgheater hose routing.jpgCJ heater valve.jpgNPD water valve.jpg
 
Do you still have the original valve? I ask, because mine stopped working a while back. It was stuck closed. I removed it, cleaned it with brake fluid, then let it sit in vinegar overnight, and now it works perfect.
 
Do you still have the original valve? I ask, because mine stopped working a while back. It was stuck closed. I removed it, cleaned it with brake fluid, then let it sit in vinegar overnight, and now it works perfect.
Unfortunately no, I bought the car about this time last year without an engine or much of anything else under the hood.

Mach 1 10.jpg
 
Does any one have good pictures( preferably ) or diagram where the heater hose valve is mounted? My HVAC on my Q code was half missing when i got it. Thanks!
 
See attached pix. This is a 302 application. The 351c heater valve position and "S" hose are the same but the motor is bigger.
Thank you that does help. I'm not sure about the Cleveland differing with both hoses coming out of the water pump instead of the manifold like the Windsor based engines. Thank You
 
Attached are 2 pictures of the hoses on my 351c. The hose from the valve to the block is routed along the top of the valve cover using a 90 degree bend Dayco "8406 Molded Coolant hose, Black". This is not a stock Ford hose.
The hose from the heater core to the pump is routed along the shock tower. I hope this helps.
 

Attachments

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Attached are 2 pictures of the hoses on my 351c. The hose from the valve to the block is routed along the top of the valve cover using a 90 degree bend Dayco "8406 Molded Coolant hose, Black". This is not a stock Ford hose.
The hose from the heater core to the pump is routed along the shock tower. I hope this helps.
Thank You!! i will save the pics and gather parts!
 
More valve questions please! You guys have been a great help.One more request. Does any have good pictures of where the control valve located and is it mounted to any thing? Thank You in advance!!
 
The heater valve is not attached to anything other than the end of the "S" shaped molded hose from the heater core. See the attached pix. The white nylon clip is a cable clamp from Home Depot.
 

Attachments

  • 71 Mustang Heater Valve.JPG
    71 Mustang Heater Valve.JPG
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The heater valve is not attached to anything other than the end of the "S" shaped molded hose from the heater core. See the attached pix. The white nylon clip is a cable clamp from Home Depot.
Hum......my engine didnt have one of these valves. I have a 351c but no air. Is the valve specific to air conditioned cars? or do non air cars have it as well?
Thank you
 
Hi tpj71mach

I looked at your original picture. In addition to the valve, you will need the Vacuum Reservoir Canister for the heater part of the system to operate properly. You should have 2 loose vacuum hoses on the firewall under the hood. 1 for the Vacuum Reservoir Canister and 1 for the valve.
 

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