Lotus Elan

Do i have a vacuum leak on my headlamps?

PostPost by: prezoom » Tue Feb 06, 2018 4:48 pm

I found my vacuum loss to be in the switch itself. The rubber block that slides over the vacuum ports had become hard with age. Along with the fact that the area where the block slides was not exactly flat. I followed Emma's post on taking the switch apart, and draw filed the uneven portion until it was truly flat. The rubber block was also made flat by sanding the block against a piece of sand paper on a flat surface. Additional pressure was added by putting a small piece of rubber in the "V" portion of the flat spring to press the block harder against vacuum ports. Some rubber lube also helped to provide more of a seal. My non-fail safe S2 will now keep the pods up for a little over 4 days after the engine is shut off.
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PostPost by: 1owner69Elan » Wed Feb 07, 2018 7:14 am

My vacuum leak was also in the switch. Easily assessed by temporarily bypassing the switch and seeing if the vacuum holds.

If you don't want to attempt refurbishing your switch an alternative, as has been discussed before, is to use a vacuum solenoid actuated by the original light switch.

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I included a small vent filter for the open leg (vent to atmosphere - kills vacuum), just to ensure no foreign material could enter (suggested by another post).

img_8605.jpg and

Then the other ports are connected to the existing vacuum lines.

My failsafe lights now stay down indefinitely and don't creep up at all over time. The solenoid is just tucked into an available space behind the dash by the heater. It's small so it fits fine, just rests in there. The headlights function as originally, only better.

You can use an NO (normally open) version for the failsafe lights and an NC (normally closed) version for non-failsafe. Needs to be a direct actuating solenoid that works with vacuum.
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PostPost by: Stevie-Heathie » Tue Feb 13, 2018 11:52 am

Interesting thread. My lights stay down a couple for only a couple of minutes so I likely have a leak. I?ll follow the recommendations above. My Cylinder #1 also has a habit of fouling so hopefully rectifying the vacuum leak will also help with that.

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PostPost by: sdenny » Sun Apr 01, 2018 8:27 am

Just to close this out from my point of view, i eventually traced it to a leak between the reservoir and the switch.

I managed to prove the integrity of the manifold to reservoir and vacuum units on the pods by connecting a length of pipe in place of the T peice and then directly to the join on the passenger side pod. As soon as i started the engine, the pods rose and then remained up with the engine off.

This lead me to suspect (as well as the hissing i heard from behind the dash with the switch bypassed) the either the reservoir->switch or switch->lamp was leaking. With a willing assistant holding a finger over one end, I blew in to the other end. the switch->lamp almost gave me a burst blood vessel, but on the switch->reservoir i could here the hiss behind the dash.

I was able to pull that pipe out, feeding in some electric flex, measure for a new pipe, then pull the new one back though (by pulling the flex, swearing and a bit of random waggling under the dash). The old pipe was obviously damaged (i suspect just an old age thing on a bend, although i guess it could have been pinched). Result is that the head lamps now raise much more quickly and remain up (i've only waited 20 mins, but it's much better than the 20 sec previously) when the engine is stopped.

Of course, I've now realised there's not much use leaving the headlamps up, as you can't (or I can't) turn the sidelamps off with the headlamps up...... Is that how a +2s with non-failsafe lamps is supposed to work?

But at least I'm much more confident that the lights will actually rise and stay up.

Thanks for all the suggestions
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