Lotus Elan

How fast should the headlights go up and down?

PostPost by: hastu » Thu Feb 15, 2024 8:40 am

I have now installed all the vacuum parts of the Failsave in my +2S 130. When I start the engine, it takes several minutes for the lights to finally lower. After about 4 minutes they are completely down, is it normal that this takes so long?

When I switch the engine off, the lights are up again after 30 minutes at the latest. Several threads say that the vacuum should last up to 12 hours. Does this also apply if the engine has only been running for a short time, or does it have to have been running for longer beforehand?
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PostPost by: Lotus fan » Thu Feb 15, 2024 9:45 am

You must have a leak somewhere.
Mine lower within 10 seconds of the engine starting, and can stay down for around 3 days.
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PostPost by: hastu » Thu Feb 15, 2024 9:49 am

Lotus fan wrote:You must have a leak somewhere.
Mine lower within 10 seconds of the engine starting, and can stay down for around 3 days.


So fast!!! I must really have a problem with a leak.

Many thanks
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PostPost by: hastu » Thu Feb 15, 2024 10:21 am

For Testing i have no Switch in the Pipes. Vacuum Pod, Pipes, Valve are all new. So the Leak can also only be in the Reservoir.
Or is it possible, that the Engine not deilver enough Vacuum??
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Last edited by hastu on Thu Feb 15, 2024 11:11 am, edited 1 time in total.
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PostPost by: ericbushby » Thu Feb 15, 2024 10:49 am

There is usually a one way valve in the vacuum pipe from the manifold. You have not mentioned that, so is it OK.
Or there must be some air getting in somewhere.
Although mine is an Elan without the fail safe system the lamps rise in a few seconds and will hold for a few hours.
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PostPost by: gus » Thu Feb 15, 2024 11:56 am

Have you tried driving the car? I had a vacuum check valve so tight that it would only open on trailing throttle. Lights would stay down for weeks though. With no reservoir
Do the lights move freely by hand? With no vacuum they should push down against spring pressure smoothly and pop up aggressively
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PostPost by: gus » Thu Feb 15, 2024 12:01 pm

Check all the joints
Try eliminating the reservoir
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PostPost by: gjz30075 » Thu Feb 15, 2024 1:36 pm

You don't show the switch in your diagram. On my failsafe Sprint, I found my oem switch leaking and
couldn't repair it so I adapted a Corvette switch and it works great, up and down,.
https://www.ebay.com/itm/154652004194?e ... R4Se0s-1Yw

I wanted it to look OEM so I adapted the switch to fit a Zephyr headlight switch so I can use the oem knob.
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PostPost by: Matt Elan » Thu Feb 15, 2024 2:44 pm

Mine go down quickly - in seconds - and then will stay down for hours when left with he engine off so it sounds like you have a leak. Do you have the separate vacuum solenoid and single 'pull down' unit?
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PostPost by: pharriso » Thu Feb 15, 2024 3:22 pm

gjz30075 wrote:You don't show the switch in your diagram.

Greg, that's because he's eliminating the switch just to test everything else...
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PostPost by: gus » Thu Feb 15, 2024 3:31 pm

Headlights should fly up.
Occurs to me now that without a switch, how are you testing?
If you are disconnecting the hose and allowing the entire system to come to atmosphere, then that might be the issue
It takes time for the reservoir to drain
With a vacuum switch properly installed, it vents only the vacuum pod, not the reservoir
So, until you get a switch try this:
run a loop up with a joint you can get at that is only going to the vacuum pod.
after the vacuum pulls the lights down, open that joint
The vacuum pod is now separate from the reservoir, and they should pop right up
Of course in this test the reservoir is also empty and the engine will rev up unless you clamp the hose off
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PostPost by: hastu » Thu Feb 15, 2024 4:25 pm

Thank you Guys for all your replies. I will test all this things over the WE
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PostPost by: andyelan » Thu Feb 15, 2024 7:15 pm

Hi There

From what you say, I would suggest that the most likely cause will be a leak in the chassis reservoir so try bypassing it.

On my car I ignore the reservoir and run the pipes directly to the vacuum pod. With this set-up the lights will stay down for weeks with the only downside is that, if they are lift in the up position, they can only be lowered once the engine is running.

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PostPost by: JimE » Fri Feb 16, 2024 9:15 pm

I have the stock factory failsafe on my 1974 + 2 and my headlights have always stayed permanently down when not in operation. JimE
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PostPost by: gus » Fri Feb 16, 2024 11:17 pm

Well, since the headlights are held down by vacuum and up by springs, this seems really unlikely. A 74 would not be a Federal car, so are you sure have failsafe lights? With a heavy spring and new o ring in the original check valve, and no reservoir, it took about 2 months for my lights to come completely up with new actuator, and an electric solenoid, but when I bought the car, shutting the door caused the lights to make their first grunt
I had several years where the lights would stay down completely overnight, but that is best case with new components
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