Don't throw away old check valves

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dcm5652
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Re: Don't throw away old check valves

Post by dcm5652 »

I have repaired the 2 vac tanks put oil on yhe manual door valve (it is not disappearing ) and when I try to pull a vac on the hose going to the inside of the car is when I notice a quick vac loss, I don't have the auto lights on this car, ( I do have on the other) I can pull a vac on the line going to the tanks and plug the line to the inside and the seem to stay shut. So it looks like a new headlight switch is in order. Thanks for everyones help Danny
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Brandon K Love
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Re: Don't throw away old check valves

Post by Brandon K Love »

Another tip for troubleshooting vacuum leaks:
On my '71 Mark, I had replaced all the vacuum hoses, and all other components which were leaking, and still had a slow leak.
I finally discovered this was coming from the rubber junction where the hoses go through the firewall-it had slightly perished.
I inserted pieces of copper tubing through the junction, hooked up the hoses each side.
The headlamp covers now stay closed, in fact I've never seen them opened after the car has been undriven, even for 2 months.
'68 Eldorado
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sauceman
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Re: Don't throw away old check valves

Post by sauceman »

Here is the manual release valve;

Image

This is located behind the left headlight assembly on the inner fender.

This is the check valve;

Image

Located above the brake booster.

Now a point to remember, if you feel the desire to muck around with the manual release valve make sure it's clean and it wouldn't hurt to spary some Wd-40 on it. The reason I mention this is because I was showing a friend on his Mark V how it worked and the bloody thing wouldn't hold vacumm after I twisted it. So a word of caution when messing around with these older vehicles.



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Castrosua
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Re: Don't throw away old check valves

Post by Castrosua »

I wouldnt panic about the manual release valve too much. Ive mucked around with it, and afterwards it would hold vacuum for about half an hour, but in time i guess the gunk, dust whatever built up again and it was back to normal

Thats the lazy way out of fixing it right lol
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1977lincolnmarkv
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Re: Don't throw away old check valves

Post by 1977lincolnmarkv »

I find that most of the time if the check valve has a leak back and the diaphragm isn't good, FORD made in 1981, an in line one way check valve that will take care of that issue. It comes with about 6 inches of vacuum line and plugs right in line. I like to put them in near the manifold and you never know they are there. Also, I have been able to get my headlamps to stay down for 6-8 months depending on how long I don't use the car. I'm sure they would stay longer but I haven't let my cars go any longer than 8 months without starting them. I have found that the issue is mostly in the switch and or in the electro-pneumatic box. I first open the box slide out the rubber block, clean it well and apply new Lithium (thick type) grease back in place of the old dried out grease. Reassemble and check with a vacuum guage. I have found that has always stopped the leak down on the box. On the headlamp switch, I drill out the rivets, remove the old grease (like I did with the electro-pneumatic box) and re-grease and re-assemble the unit and find that the switch will hold vacuum. Sometime on the switch I have had to go back and re-do it, because of a slight leak down on one of the outlets. Once I have gotten all these components air tight. I never have headlamp issues, EVER !!! The actuator door motors usually never go bad unless they have rusted through. This has solved all 6 of my Marks headlamp systems. My latest 7,500 mile Mark wouldn't hold down more than 12 hours before I saw its eyes wide open. I did my trick and now its been 3 weeks and they are still shut and TIGHT. I have to thank my friend Chris in Canada who taught me how to re-built them and isolate the leak.
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Re: Don't throw away old check valves

Post by Bamboobert »

I know it‘s an old topic, but I have this problem of headlight doors opening a few hours after I turned of the engine of my 72 Mark4. I built out the actuator, but how do I check it? When I close the lower connector the actuator gives resistance when moved. When I close the upper connector there is no resistance.
I can‘t really figure out how the actuator works.
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Dan Szwarc
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Re: Don't throw away old check valves

Post by Dan Szwarc »

The vacuum motor, as they are commonly known, has a diaphragm inside.
Vacuum on the bottom pulls the rod IN/down.
Vacuum on the top helps pull the rod OUT/up.
There MAY also a SPRING inside pushing up to help the rod move out. This is easily verifiable by hand.

If the bottom can hold a vacuum, then the diaphragm inside is OK and there isn't a pinhole in the body.

However, there is also a shaft seal where the rod comes out of the top. This seal commonly fails due to age or if the rod tears it due to corrosion. The accordion boot is just a dust boot.

It is possible to replace the O-ring. There are also companies that rebuild these (like west coast classic cougar on the... west coast).

Truth is, if if you have the one with the spring, then you don't even need the top vacuum line to connect or the shaft seal to be intact or leak-free. Just cap the line on the car and let the spring open the headlamps. No one will know but you (and me).
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Re: Don't throw away old check valves

Post by Bamboobert »

Ok Dan, thats helpfull. I checked, my motor doesn‘t have a spring, the diaphragm is ok, the shaft seal at the top is probably broken.
Anyway, my problem is that the doors open a few hours after I stop the engine. So there is a vacuum loss. When the diaphragm is ok, there has to be a problem somewhere else.
I‘ll start checking.
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