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Unfortunately the heater valve for the S Type which is a vacuum switch cannot be easily opened and they are no longer produced. They are sealed around the circumference with a folded joint which can only be opened by grinding it off. Once opened it cannot be resealed and there are no repair parts available anyway.
I have taken one apart that was leaking from the small air hole in the lower half and the pictures below are what I found. There are two reasons why the valve will leak. The first is that the rubber diaphragm inside has perforated allowing water to pass from one side to the other. The second which can be seen in the photos of my old one is that the centre of the diaphragm rusts out again allowing water to pass. The way the valve works is that the vacuum pulls down the diaphragm which in turn pulls down on a sealing ring which allows water to run through the valve body. The water is in direct contact with the rubber diaphragm. Over time the change in heat cycles can cause damage to the rubber or if the engine has not been run with the correct coolant with rust inhibitors the centre of the diaphragm can just rust out.
Many of us with S Types have spare vacuum switches tucked away just in case so if you see one which works buy it. Failing that there is an alternative. SNG supply a replacement vacuum valve which comes from an XJ6 for the S Type. This one works slightly differently as the water goes nowhere near the vacuum side of the valve but works the same way as the original valve which is opened by the vacuum. This is a slightly altered switch in that the original S Type valve is constantly closed and the vacuum opens it. The original XJ6 valve was constantly open and closed when the vacuum was applied. The SNG valve supplied for the S Type has been altered to be constantly closed. It does not look the same as the original valve but where it sits in the engine bay you are hard pushed to see it if originality is your thing.
Original vacuum valve showing air hole where it leaks.
With the folded rim ground away.
Showing the valve opened. The lower half (vacuum side) to the right with the rubber diaphragm still in the upper half to the left.
Peeling back the rubber diaphragm and the amount of rust was in there.
Still the top half of the valve showing the rust. The rubber diaphragm is on the right and on the left is the seal which is pulled down by the diaphragm.
The bottom of the seal cleaned up and you can see the damage caused by the rust on the left.
The seal is held in with rivets so when these are removed you can see how the water flow goes.
All the components of the valve laid out. Not repairable I am afraid.
This is the difference between the original S Type vacuum valve on the left and an original always open XJ6 valve on the right.
On the left is the SNG altered XJ6 always closed valve compared with the original XJ6 always open valve.
Last edited by Cass3958; Jan 17, 2023 at 05:52 AM.
I believe that Jose has some good ones if originality is important to you. Just ask him (PM) & maintain proper coolant concentration. I bought a very good one from him.
Last edited by Glyn M Ruck; Jan 17, 2023 at 06:44 AM.
the original heater valves are almost 60 years old and will fail as soon as the rubber diaphragm inside comes in contact with hot coolant, not worth the trouble. The one that Glyn got from me was the proverbial "1 in a million" part.
The 3.4 and 3.8 S type use a NORMALLY CLOSED, OPENS WITH VACUUM heater valve with 5/8" IN / OUT coolant hose ports, and a 1/8" vacuum hose port.
Any heater valve with the above specifications will do the job of allowing coolant to flow to the Heater Matrix / Core, or to stop it from flowing / circulating. .
In my 3.8 S, I fitted a Factory Air 74614 heater valve that has the same specs above and works perfectly. Originally designed for 1965 Ford Galaxy, but the specs are the same.
The Factory Air heater valve is cheap and abundant. I tried the XJ-6 Series 1 heater valve and decided against it because it is bulky and heavy, not to mention expensive.
Try www.RockAuto.com for the Factory Air valve, they ship worldwide. NOTE that Factory Air parts now sell under the name "Four Seasons" but with the same part number 74614.
I think there are some normally closed vacuum operated valves used on US originated Ford cars. If there's a distributor of US Ford parts in South Africa, it might be a good option.
the original heater valves are almost 60 years old and will fail as soon as the rubber diaphragm inside comes in contact with hot coolant, not worth the trouble. The one that Glyn got from me was the proverbial "1 in a million" part.
The 3.4 and 3.8 S type use a NORMALLY CLOSED, OPENS WITH VACUUM heater valve with 5/8" IN / OUT coolant hose ports, and a 1/8" vacuum hose port.
Any heater valve with the above specifications will do the job of allowing coolant to flow to the Heater Matrix / Core, or to stop it from flowing / circulating. .
In my 3.8 S, I fitted a Factory Air 74614 heater valve that has the same specs above and works perfectly. Originally designed for 1965 Ford Galaxy, but the specs are the same.
The Factory Air heater valve is cheap and abundant. I tried the XJ-6 Series 1 heater valve and decided against it because it is bulky and heavy, not to mention expensive.
Try www.RockAuto.com for the Factory Air valve, they ship worldwide. NOTE that Factory Air parts now sell under the name "Four Seasons" but with the same part number 74614.
These black plastic valves work a treat. There is a company in Australia that rebuilds the originals but I can't find it. Maybe Bill Mac will comment from Aus. They un-seam them perfectly & they end up looking as new. They even re-manufacture the innards including diaphragm ~ I suspect they have found a supplier of parts that will fit & work. I really doubt they could do it economically otherwise.
Last edited by Glyn M Ruck; Jan 18, 2023 at 12:10 PM.
I think the one Jose sold me came from a car that had had the unit replaced in it's life & that the final fastidious owner had maintained coolant concentrations correctly. I had a choice of 3 in a photograph & there were clear signs to me that the unit I feared had a crack in it had certainly been run with coolant from the lack of marking on the inlet & outlet. Coolant creeps under the clamped area of the hose & keeps the surface bright. It was the only one of the 3 that still had a bright inlet & outlet. Jose assured me that the mark was not a crack and was true to his word.
Last edited by Glyn M Ruck; Jan 18, 2023 at 01:44 PM.
Thanks everybody, I found the plastic valve on amazon, think I will go with that. The SNG valve is very pricey, it's a shame though, my original valve still looks perfect but is leaking so I assume the diaphragm is broken on the inside.
Thanks everybody, I found the plastic valve on amazon, think I will go with that. The SNG valve is very pricey, it's a shame though, my original valve still looks perfect but is leaking so I assume the diaphragm is broken on the inside. Appreciate the advice.
if it leaks through the "weep hole", a tiny hole on the side of the valve body, the diaphragm is shot. But don't throw it in the trash. One day someone will come up with a way to rebuild these valves,, or remanufacture them new.
If you live in a mild climate like I do and never need a heater. Just pop rivet the weep hole closed. My old one was like that forever. The valve is normally closed.
Last edited by Glyn M Ruck; Jan 19, 2023 at 09:10 AM.
it's a shame though, my original valve still looks perfect but is leaking so I assume the diaphragm is broken on the inside.
Could be either the diaphragm or just rusted out. In the photos I showed my diaphragm was in perfect condition, in fact I still have it in a box with all the other parts but mine as you can see had rusted out. If you flush it out with water whilst trying to open the valve with a vacuum the colour of the water being flushed will tell you a story. But either way it is broken and unrepairable at the moment.
if it leaks through the "weep hole", a tiny hole on the side of the valve body, the diaphragm is shot. But don't throw it in the trash. One day someone will come up with a way to rebuild these valves,, or remanufacture them new.
We are ODD parts fabrication providing Obsolete, Discontinued, and difficult-to-obtain parts since 1990. This heater valve also fits Aston Martin DBS. We are restoring a James Bond Version car that needs to be EXACT in every detail. We have been restoring "Pinched Seam" canisters like this since 1990. This heater valve has two diaphragms in it. We are about to recast these diaphragms in superior Urethane synthetic rubber. Yet, we need at least six valves to defer the costs of the molds. We use dental Silicon master molding techniques to reproduce exact parts. This valve is exceptionally complex- having a bolt circle that retained the fluid diaphragm. Ours is apart and ready for diaphragms. Corroded alloy original castings can be repaired using Muggy Weld. Steel parts fixed as well. We have been there and done that. We will be able to supply diaphragms, and or repair assemblies. THIS IS NOT AN ADVERTISEMENT! We are far too busy to entertain any more business. I am just reaching out to the few who appreciate originality and our capabilities. This is a case of getting something unique done on a very small scale. Find me and contact me if interested. This is just like a referral that someone might make in a forum like this. However, if I have violated some forum rule- I apologize, and you may delete my inquiry for my perhaps controversial proposal. Nobody is getting rich here- just trying to solve some unique short production needed parts problems. Thank You. Jim Simpson and crew.
We have restored thousands of Vacuum advances, turbo boost pull-off vacuum canisters, headlamp lift motors and similar. We have tools for opening and closing the pinch seams. AND typically, we wrap the diaphragm material around and through the pinch seam to assure total sealing during reassembling that also averts material shrinkage related diaphragm pull-out that is so common a failure in OEM pinch seam assemblies that fail. In THIS case, a cast diaphragm fits well and locks into provided concentric rings in both diaphragms requiring OEM shaped cast parts. PLEASE note that OUR Aston Martin DBS unit (looking exactly the same as photos on this forum) appeared to have the retainer ring riveted. Not so on ours. On closer inspection- the rivets appeared to be fine thread screws. In fact, after cutting a deeper common screwdriver slots into the head of each and removing with an impact screwdriver--THEY WERE SCREWS. I have thread pitch and diameter at the shop- but not here. I can advise later. They were sealed with a white adhesive and polished on the outer visible side of valve and unseen until removed. The smaller spring is quite severe in strength, and we FABRICATED a multi piece diaphragm- using a syringe plunger to captive the nail-head pusher foot and CA adhesive. Not enough room for our tiny movement open-to-closed. Long story is that did not work. Casting OEM shapes is really the best. I would love to purchase your cores and restore them to offer for sale as upgraded OEM. I cannot say final pricing on restored units because each would be its own case. So far I have not been kicked off this forum. so, can you contact me through oddparts dot net? And send us a price? Perhaps I can offer a repaired valve in exchange for several cores? QUOTE=Jose;2845837]Superb !
I have 3 or 4 of the original dead Heater valves that I can supply.
Yes there are two diaphragms, one is the large Bell-shaped, and the other is a US half dollar coin-sized that is rivetted to the top aluminum cover.
How are you solving the removal and re-attachment of the rivetted small diaphragm ?
contact me by private message. I am in US.[/QUOTE]
You can always use another Heater Water Valve From SNGBarratt BD33049
It's has a 90deg angle, but not to hard to use that, it's vacuum controlled anyway.
You can always use another Heater Water Valve From SNGBarratt BD33049
It's has a 90deg angle, but not to hard to use that, it's vacuum controlled anyway.
that is a Series 1 XJ-6 heater valve, Normally Closed, Opens with Vacuum. Very clumsy, not original. I rejected it.
but you can also used a cheap Made in china heater valve for a 1965 Ford Galaxy which is compact and almost the same size as the original, this is the one I fitted to my '65 S type. Works perfectly. Why pay for a XJ-6 heater valve when you can resolve the issue with a $20. heater valve available at all autoparts stores in the US ?
I want the original heater valve, it's a work of art. Seems like the S type and 420 were built around the Heater Valve !!, complete with a bracket.
Too bad they perish after 45+ years.
Jaguar changed the configuration of Heater Valves starting with Series 2 XJ. They went Normally OPEN closes with Vacuum, the opposite of the S type.
