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Hi Everyone,
I just picked up a 71 Cutlass Supreme from AZ and the heater is disconnected. I'd like to reinstate heat but I'm not sure where the hoses should connect or if I need a heater control valve? The car does not have AC and the current setup has a hose coming off the water pump going directly to the rear manifold. I'm not sure why the heater was disconnected in the first place but did flush the heater core and there was no leaks. Any advice would be appreciated!
The long hose from the water pump connects to the top heater core nipple, and the connection at the back of the block where the current hose is running connects to the bottom one.
Last edited by BSiegPaint; Nov 8, 2018 at 12:06 PM.
First, you can pretty much be assured that the reason why the heater is disconnected is because the heater core leaks.
Second, the inlet hose from the back of the intake to the bottom port on the core is 5/8". The return hose from the top hose on the core to the water pump is 3/4". They only connect one way. There is no control valve used on non-A/C cars.
I would agree with Mr. P. about the heater core leaking. Flushing some water through it is not the same as putting it under 15 psig of pressure. There would be no reason to bypass the core if it weren't leaking.
I would agree with Mr. P. about the heater core leaking. Flushing some water through it is not the same as putting it under 15 psig of pressure. There would be no reason to bypass the core if it weren't leaking.
Well, he DID say it was from AZ, and since it's a non-A/C car, there's no heater control valve to turn off flow through the core.
First, you can pretty much be assured that the reason why the heater is disconnected is because the heater core leaks.
I agree with that. The reason it was never repaired is because the car was in Arizona.
I just remembered that on non-AC cars there should be a restriction in the hose nipple screwed into the rear of the intake manifold. It should have a 1/4" hole to reduce the water flow and prevent the heater core from blowing out.
First thought I had was it was disconnected due to the AZ heat. If it has been disconnected for any extended time it's most likely junk. As previously stated, running water through it doesn't tell much but you also need to factor in the 180 to 190* heat that will run through at 15lbs. Things are going to expand and drip.
My question to all the responders: Is there a reason you cannot add the heater control valve on the back of the intake? Are the controls in the car different? I don't recall ever owning a 71'-72' without AC so I'm not sure about the controller, but I know plenty exist. Is it possible to run a vacuum line off the controller to a Heater Control Valve(HCV)? If so, why not install an HCV to keep the heat from circulating through the heater core? Really there is enough heat that transfers off the engine through the firewall already so any bit of reduction would help.
My question to all the responders: Is there a reason you cannot add the heater control valve on the back of the intake? Are the controls in the car different? I don't recall ever owning a 71'-72' without AC so I'm not sure about the controller, but I know plenty exist. Is it possible to run a vacuum line off the controller to a Heater Control Valve(HCV)? If so, why not install an HCV to keep the heat from circulating through the heater core? Really there is enough heat that transfers off the engine through the firewall already so any bit of reduction would help.
The heater-only control head is cable operated. There is no vacuum source and no vacuum switch to operate the heater control valve. The controls are obviously different. If a person in AZ wanted to stop flow through the heater core in hot weather, installing an aftermarket manual valve in the heater line would do it easily. Many cars in the 1950s had such a device.
Yes Joe, thanks for jogging my memory. I remember an ex girlfriend having a 67' Tempest that had those cables. One broke at the plastic mounting screws and it was a b*$%h to find a replacement. Never saw them on the later A bodies though.
The restrictor is in either the hose nipple on non-AC cars or in the heater valve on AC cars.
Yes sir that is what I meant. The threaded single barb fitting at the rear of the intake is an engineered metered "restrictor" fitting and must be in place on a NON-AC car. If not the heater core wont last long with full system pump surge pressures. It will self destruct even fasted if its chineasium.
You just need a 1/4" hole to reduce the water flow and prevent the heater core from blowing out. Any method of achieving this would work, such as a pipe plug with a hole drilled in it.
Hey guys I live in AZ now.
And it seems to me every car I buy from AZ the heater core is disconnected.
I think because they don’t want the heat in the car. And every time I kid myself saying it won’t leak it Disconnected for the heat , but surely does leak.
when unhooked for awhile they seem to go bad. I havnt found a good one yet, so like this convertable I just bought it most certainly leaked also. Lol
I didn’t want to get my new carpet Antifreezed
so I did the core.
heat or no heat I hook all my heater cores up because it does get chilly at night in AC believe in not around January.
Last edited by JOHNNYOLDS442; Jun 27, 2020 at 07:13 AM.
