Back to the Headlight Vacuum

[ftsoft]

I finally got back to diagnosing the problem with my vacuum headlights. Previously on this program, I had removed the reservoir from the system and put in a one-way valve to replace the T connector. All was well for a few months and then the system failed in, what I thought was a strange way. The headlights wouldn't come up, but if I raised the right-hand pod, the left-hand pod would raise itself and the pods would stay up well while the car was running. I'm 90% sure that the need to raise the rt-hand pod is due to a leak somewhere in the tubing that runs from left to right. Getting back to the system this week, nothing worked at all, so I removed the one-way valve and blocked the tubing from the left t right pod just to see if there was any vacuum at all. This worked and the left-hand pod raised on it's own. Hooking up the tubing to the right pod took me back to having to raise it to get the pods up at all. I'm pretty sure that this won't work very well when the car is on the road, so I need to replace the valve. Looking at the valve, it's pretty cruddy looking, and I'm theorizing that crud has crept into the valve and cause it to leak (the mighty-vac confirms a slow leak). My question (finally) is has anyone used a filter in front of the valve? Does this work? I notice that the old Corvette system uses something similar. Anyway, if you got this far, thanks for reading.

Frank

[oldelanman]

Hi Frank,
I'm afraid I haven't read your earlier post so I don't know why you have bypassed the vacuum reservoir but the symptom you describe where you need to assist the lamps to rise is consistant with there being insufficient stored vacuum available.
This may be all that's wrong and you are now chasing a fault which doesn't exist.

Regards,

[ftsoft]

I bypassed the reservoir because I suspected that it leaked. The pods wouldn't rise at all, nada. When I bypassed the reservoir and installed the one way valve, the system worked very well, even under a load. My suspicion is that the reservoir is only required if you want the pods to stay up after the engine is turned off. My experience seems to bear this out. I was worried at first that putting a load on the engine would cause the pods to retract without the reservoir, but this just didn't happen. The system worked for a few months before things started to go south. I should say that I had tried new T connectors in the past using the reservoir with no luck. Most of the tubing is original, so I need to replace a lot of it. I worry that a new one way valve will only last another few months.

Frank

[oldelanman]

Frank,
I think the reservoir is there to ensure that the pods rise rapidly particularly when the engine is pulling hard and not making much vacuum. Once they are raised however, provided the system has no leaks and the non-return valve is working, they should stay up even without the reservoir.
Have you tested the actuators themselves and the pull switch on the dash for leaks ?

One other thought....do the pods move freely on their pivot bolts ? If they are siezed the actuators will struggle to raise them.

Regards,

[ftsoft]

You may be right about the reservoir in some situations, but I just didn't see that in the limited use that I had. That's a good suggestion about the pods moving freely. I'll check that. I'm working my way through the various components. I noticed that an archived post suggested using this valve

Swagelok #B-2C4-1

http://www.swagelok.com/search-results/ ... qs=B-2C4-1

Does anyone have a pic of it installed?

Frank

[mcclelland]

Hi Frank,
I have had problems over the years and for me its nearly always lead back to the non return valve which seems to get dirty and then leaks.
I think your idea of using an in line filter is excellent and wonder has anyone already used one?
Good luck, George...

[RotoFlexible]

I recently went through the entire vacuum system in my car. I found it useful to unit-test the various components - reservoir, individual pods, switch, one-way valve - with the Mity Vac. Assuming that yours has a vacuum gauge, you can evacuate a component to a specific vacuum and watch the gauge to see how quickly it leaks. This will help you isolate the problem to (hopefully) a single component.

If the left pod comes up when you raise the right pod by hand, that suggests a leak in the right pod that is partially sealed when the pod is up, allowing enough vacuum to develop to raise the left pod. The system may have further degenerated preventing even that from working.

The reservoir has the capacity to allow the headlights to come up quickly, but only if there are no leaks in the system. My pods were very sluggish and would not remain up long with the engine off before I overhauled the system. Aside from slow or unreliable headlight operation, keep in mind that a leaky vacuum system dumps air into No. 1 manifold and messes up your mixture and idle. The system should be made as non-leaky as possible!

The switch is rebuildable, if you exercise caution taking it apart. Excellent photos in this thread. If your reservoir is leaking, you may have a more serious problem than a vacuum leak - check the area where the turrents are welded to the crossmember for rust.

[ftsoft]

Rotoflexible: I hadn't thought about the effect on the mixture. Good point. I plan to test all of the components and replace what leaks and replace all of the tubing. I'm just learning how to use the Mighty Vac. BTW I had my Elan in Western Mass. in the late 60's. I miss those roads.

Frank

[nigelrbfurness]

Whilst this isn't the main topic of this thread, you might find it interesting over the years I've been running Elans (35+, OMG I'm so old now...) I've had several failures of the non-return valve. In each case I have successfully replaced it with a bicycle tyre inner-tube valve (last one cost me 18p) forced into a section of plastic tubing heated in boiling water to soften it then inserted into the vacuum pipe from the head. My current car is using one right now and its been in there over 15 years... The headlights never fail to pop up and stay up!

Best wishes to all, I never tire of reading this mailing list!

Nigel

[RotoFlexible]

Whilst this isn't the main topic of this thread, you might find it interesting over the years I've been running Elans (35+, OMG I'm so old now...)

44 years here, but then I was only 16 when I started.

I've had several failures of the non-return valve. In each case I have successfully replaced it with a bicycle tyre inner-tube valve (last one cost me 18p) forced into a section of plastic tubing heated in boiling water to soften it then inserted into the vacuum pipe from the head. My current car is using one right now and its been in there over 15 years... The headlights never fail to pop up and stay up!

That is brilliant! Presta or Schrader? If Presta, the knurled knob has to be loose to allow the valve to open, but must not come off entirely or the valve stem could be sucked into the engine .
I used an old Presta valve to introduce high-pressure air into a sticky brake caliper I was overhauling. Couple of strokes with the bicycle pump and stand back!

[nigelrbfurness]

As I recall it wasn't the type with the knurled knob - I have those on my vintage ten-speed. The valve was widely used on children's bikes in the 70s and 80s and are still available today, though I can't see any on ebay! They have a shoulder which is used to clamp them into the tube with a knurled threaded ring on the inner tube. I might still have one somewhere, they came in packets of four - if I can find it I'll take a picture! But I imagine any tyre valve can be adapted to work just as well. After all, there's hardly any pressure involved. I also recall in my younger days when i really keen making up a threaded thingy in two pieces from brass tube to hold the valve. Life's too short now and plastic tube works just as well!

Nigel

[ftsoft]

Whilst this isn't the main topic of this thread, you might find it interesting over the years I've been running Elans (35+, OMG I'm so old now...) I've had several failures of the non-return valve. In each case I have successfully replaced it with a bicycle tyre inner-tube valve (last one cost me 18p) forced into a section of plastic tubing heated in boiling water to soften it then inserted into the vacuum pipe from the head. My current car is using one right now and its been in there over 15 years... The headlights never fail to pop up and stay up!

Best wishes to all, I never tire of reading this mailing list!

Nigel

Holy Moly! As an avid bicycle rider I have an infinite supply of both Presta and schraeder inner tubes. So, you just cut the valve out then?

Frank

[nigelrbfurness]

Cutting them from the inner tube would probably be fine, but the ones I used were not integral with the tube. I'll look later and see if I can find one to post an image of.

Nigel

[nigelrbfurness]

here's picture of the type I used, I'm sure:

http://www.google.com/imgres?imgurl=htt ... A&dur=8278

Hmmmm didn't realise it was such a long URL. sorry.

[prezoom]

My S2 has a Schrader valve, threaded into the through bore of a piece of brass hex stock. The ends of the hex stock were then turned down to accept short sections rubber tubing, which are then clamped to the plastic tubing coming from the intake manifold and then to the vacuum control switch. Works well.

My biggest problem was with the vacuum switch itself. However, rebuilding the switch, as referenced earlier, and the use of some rubber grease on the rubber block in the switch, now will keep the headlights up for about 5 or 6 days after it is parked. I found draw filing the portion of the switch where the 2 tubes enter the switch, created a nice smooth, flat surface for the rubber block to seal against. I also used a small piece of rubber beneath the piece of spring steel, to increase the pressure of the, old, hard, dried out original rubber block.

Rob Walker
26-4889