Heater Hose in-out connection at heater core

[Stanglover]

I have just been looking through some older post on the correct heater hose connections at the heater core and block on the 1971 Mach 1 without A/C. I'm thinking mine are wrong. Not had any problems so far with circulation, cooling or heating, not that I use the heater!! I copied a friends car's hose connections, but reading recently, it was described thus; (looking at the firewall) bottom left is the INLET from the BLOCK connector, Top right is the RETURN and goes to the PUMP connector. I did not see any identification on the heater core tubes, nor can I find reference in my Ford 1971 Manuals.

Can someone please clarify this for me and everyone else who is confused.

Geoff. aka Stanglover

 

[72HCODE]

it honestly does not matter which way you have the hoses connected from a standpoint of function.

there is no flow direction in the cores, if you want to be concourse correct then ford did install them a certain way to be consistent.

once the heater core vacuum control motor pinches off one inlet to the heater core it shuts down coolant flow into the core it doesn't mater which one as the coolant will stop following into and out of the core at that point.

but there is no real direction to installing the hoses from the coolant pump to the heater core.

 

[Stanglover]

it honestly does not matter which way you have the hoses connected from a standpoint of function.

there is no flow direction in the cores, if you want to be concourse correct then ford did install them a certain way to be consistent.

once the heater core vacuum control motor pinches off one inlet to the heater core it shuts down coolant flow into the core it doesn't mater which one as the coolant will stop following into and out of the core at that point.

but there is no real direction to installing the hoses from the coolant pump to the heater core.

That was what I thought all along, I could see no reason why water needed to flow in any one direction. That saves me the trouble of getting my correctly marked hoses off to switch them around without having to cut them... and I don't have enough spare length to do that.

Thanks for clearing that up. The question has arisen before if I remember.

Geoff.

 

[Carolina_Mountain_Mustangs]

A suggestion for future. When you put heater hoses or radiator hoses on I put anti seize on the hose and fitting. They come right off if you need them off and never had one blow off in 40 years. The ridge around the end of the tube makes it pretty much impossible to blow it off. I also put some on the bleeder valves on wheel cylinders and calipers to prevent freezing. I do not get any inside the fitting it is made with ground up aluminum, glass beads or copper flakes depending on brand. You don't want than in your coolant or brake fluid.

If you did not use that stuff on thermoset molds you would never get them apart. Every fastener and heater rod got it applied. Header bolts also.

 

[rocket366]

I was told many years ago that the hose supplying coolant needs to have the heater control valve installed on it.

The reason was that when the car is fired the heater core will get SLAMMED

with coolant and will stretch the tanks and lead to early heater core failure.

I always fire the car with the heat off and after its running open the heater control valve.

Paul

 

[Stanglover]

A suggestion for future. When you put heater hoses or radiator hoses on I put anti seize on the hose and fitting. They come right off if you need them off and never had one blow off in 40 years. The ridge around the end of the tube makes it pretty much impossible to blow it off. I also put some on the bleeder valves on wheel cylinders and calipers to prevent freezing. I do not get any inside the fitting it is made with ground up aluminum, glass beads or copper flakes depending on brand. You don't want than in your coolant or brake fluid.

If you did not use that stuff on thermoset molds you would never get them apart. Every fastener and heater rod got it applied. Header bolts also.

Good point David. I only 'lubed' the tubes with straight anti-freeze to get them on, not off.

 

[Stanglover]

I was told many years ago that the hose supplying coolant needs to have the heater control valve installed on it.

The reason was that when the car is fired the heater core will get SLAMMED

with coolant and will stretch the tanks and lead to early heater core failure.

I always fire the car with the heat off and after its running open the heater control valve.

Paul

I don't think external heater control valves were on the 71 Mustang, never seen one, but then who knows what's been changed over the years. I seldom use the heater even in our climate, so it's always off.

Thanks for the reply and comment though.

 

[rocket366]

Most all cars had a heater control valve to stop hot coolant from entering the passenger compartment when

the heater is not in use.

If you heater hoses are connected than you are circulating hot coolant through the heater core at all times.

There was a heater control valve on your car originally. It was operated by supplying vacuum to the valve when heat

is off.

There are two vacuum lines that pass through on the pass side firewall near center up high. One supplies vacuum to the

heat/AC climate controller and the other actuates the heater control valve.

If you don't have a heater control valve than the vacuum line that used to go to it may be a source of a vacuum leak.

Paul

 

[Stanglover]

Most all cars had a heater control valve to stop hot coolant from entering the passenger compartment when

the heater is not in use.

If you heater hoses are connected than you are circulating hot coolant through the heater core at all times.

There was a heater control valve on your car originally. It was operated by supplying vacuum to the valve when heat

is off.

There are two vacuum lines that pass through on the pass side firewall near center up high. One supplies vacuum to the

heat/AC climate controller and the other actuates the heater control valve.

If you don't have a heater control valve than the vacuum line that used to go to it may be a source of a vacuum leak.

Paul

Thanks Paul. The car will be garaged soon for winter and I will be doing other work around the dash, so I'll double check what's there. The heater controls do work and no heat when off. It was more a question of which way do the lines NEED to be connected, or does it matter. I can change the lines around, in and out, but if I don't have to why bother.

I know this question has been raised before, but I'm sure many will benefit from a refresher.

Thanks to all for the clarification.

Geoff.

 

[OMS]

Most all cars had a heater control valve to stop hot coolant from entering the passenger compartment when

the heater is not in use.

If you heater hoses are connected than you are circulating hot coolant through the heater core at all times.

There was a heater control valve on your car originally. It was operated by supplying vacuum to the valve when heat

is off.

There are two vacuum lines that pass through on the pass side firewall near center up high. One supplies vacuum to the

heat/AC climate controller and the other actuates the heater control valve.

If you don't have a heater control valve than the vacuum line that used to go to it may be a source of a vacuum leak.

Paul

This is on cars equipped with factory A/C only.

The cars with just heat did not have any vacuum going to the control

 

[Pastel Blue]

Most all cars had a heater control valve to stop hot coolant from entering the passenger compartment when

the heater is not in use.

If you heater hoses are connected than you are circulating hot coolant through the heater core at all times.

There was a heater control valve on your car originally. It was operated by supplying vacuum to the valve when heat

is off.

There are two vacuum lines that pass through on the pass side firewall near center up high. One supplies vacuum to the

heat/AC climate controller and the other actuates the heater control valve.

If you don't have a heater control valve than the vacuum line that used to go to it may be a source of a vacuum leak.

Paul

This is on cars equipped with factory A/C only.

The cars with just heat did not have any vacuum going to the control

+1 and I believe the two hoses referred to here: one goes to the black vacuum can on the fender well and the other goes to the heater control valve.