Does anyone know why I have this valve on my heater hose? It’s a 65 “442” no A/C. It’s not connected to anything. Took a pic of cowl tag, anything unusual? Thanks for your help.

 

Oldsmobiles used a valve on the passenger's side head for years. This restricts water flow to the heater core when it's not needed. There are plenty of threads on replacing the valve and electrical switch on our forums 👇

Even my 96 98 with a 3.8l v6 had a valve between the block and the heater core.

 

Called heater control valve. USUALLY this was with cars with a/c to turn off the hot coolant going into the heater core..

 

The valve was used on non-A/C 1965 cars with V02 HD cooling as a restrictor. Apparently this was a stop-gap measure. Later cars used the restrictor nipple instead, which was obviously less expensive on the production line. Note in this page from the 1965 PIM that view B in the lower left showing the heater valve as a restrictor was added in Nov 1964 and applies to all V02 cars.

 

I was going to remove it to clean things up a bit and prevent a chance of potential leaks. If it came that way from the factory for a reason I’ll probably replace the hoses and leave it that way. I see that Fusick has a molded hose to replace the one that goes from the core to the valve. My Olds chassis service manual does not show the illustrations that Joe’s post showed. Thanks for the help guys.

 

The CSM was probably released in August 1964. That change didn't happen until Nov.

 

So that valve was used only as a restriction, it is not hooked up to the heater controls?

 

The non-A/C heater controls don't have any provision for vacuum. As I said above, it is used as a restriction.

 

Oldsguy put a hose barb on the passenger's side head of the 455 that was in his 69 Delta 88. It didn't damage the heater core.

 

Thanks again for the info.

 

Easy enough to find an NOS or new correct part. Several restoration suppliers offer a version of this. I can't find a pic of the orifice in the ID of this nipple.
Here's a NOS restrictor mislabeled as a heater control valve...

 

Should have a 1/4” hole for the restriction, which will prevent the heater core from blowing out. Back in the 90s I went through 3 heater cores before figuring this out.

 

I was thinking maybe just replace the valve with a hose! Glad I asked!

 

That bracket that holds the valve is rather tough to come by today. I think they got scrapped early in most cases.

 

Thanks for the info Peter. If I decide to replace the valve, I will definitely save the parts.

 

Gang,
My A/C equipped ‘66 Starfire has that valve to keep the A/C working against the heater core. It works great but is a possible point of failure. I replace it every 5-10 years and haven’t had a problem yet.

My heater-only (no A/C) ‘66 98 convertible has no such valve. I’ve been wondering for a decade or 2 about whether a heat-block-off valve would be worth adding to the non-A/C system & how to trigger it properly. I’ve had the 98 since the ‘80’s and have felt the heater core heat mildly venting/blowing when the kick panel vents are open. It’s not a big deal, but probably shouldn’t be…

So, if I were to install the heater core block off valve on the block, what’s a good way (i.e. which port to block?) to stop block-heated water from the heater core when the vents are open? I can imagine having it close off the hot water when the vents are activated and can plumb that, but don’t generally like fighting Olds designs.

Fun to learn about what Olds did through the years. If I can get cooler cabin somewhere near what Olds intended, great. If not, no big deal…

Cheers
Chris

 

Block the same port as the AC vehicles.

 

Years ago you could buy a cable operated control valve at just about any parts store designed to do exactly what you are looking to do. You would just close it when you were not using the heater. Don’t know if they are still available.

 

They are still available. I have one in my 62 wagon. Unfortunately, that is not what this thread is about. Go back and read it from the beginning, especially the part about why Olds used them on the 1965 cars with RPO V02 HD cooling.

 

Tj Pal looks like your heater control vacume valve does not have a vucume line going to the valve.

My 1982 engine has this same vacume valve mounted on the engine . My car has AC , my understanding is when the heat / vent / AC controls in the cabin is set to MAX AC , this sends vacume to the valve on the engine , closing off coolant flow to the heater core .

My old original AC pump is in very poor shape so do not run my AC much . To reduce heat in the cabin when the weather is really hot, i added a ball valve to the same heater hose that the vacume control valve is on . I installed the ball valve on the smaller 5/8 size heat hose . My understanding is the smaller 5/8 size is the pressure side . The ball valve i installed is low tec , i have to lift the hood to open or close the ball valve . Wife does notice the difference in cabin temp .

 

Is this the cable operated valve your thinking about?

https://www.summitracing.com/parts/fss-74828



I suppose this cable operated valve would be convenient if you just wanted to replace the OE valve with a non-restricted hose barb. Of course, anything other than an OE valve would be inappropriate for a car getting a concours restoration.

 

As per Joe P in 1965 its only function was to act as a restriction in non A/C cars. There was no vacuum line unless it was an A/C car.

 

I read that. I was wondering if the link I provided was the type of cable-adjustable valve you were thinking about.

The restricted hose barb posted earlier may have been the one @Oldsguy used on his 69 Delta 88. But I seem to recall it was just a hose barb he got at the hardware store.

 

The link you posted doesn’t show a pic of the valve, but the description they give sounds right.

 

Jesse is right, I reasoned that a simple hose barb (as pictured in post #11) would work instead of trying to replicate the original design. I worked fine for me and I didn't notice any negative side effects.

 

Yes, if all one cares about is functionality, the restricted hose barb used on later cars solves this problem. If one wants to be optically correct, the non-connected heater control valve is what the factory used on 1965 cars with the 400 motor.