Lotus Elan

Headlamp Vacuum

PostPost by: neillav » Tue Aug 10, 2004 12:55 pm

Ok, my first time on here so many apologies if this topics been done before and/or I'm just being thick.

Can someone explain the failsafe headlamp vacuum system to me ? Mine wasn't connected when I bought the car and I've piped it up as I think and the pods drop nicely at idle but then start to raise again with rising revs. I'm thinking theres a leak in the system (the chassis member seems to be favourite) but I don't understand why the pods rise proportionately with rising engine revs. Kids laugh at the blinking +2 as it passes.....

Other than the chassis member what are the other areas I should be looking at ?
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PostPost by: rgh0 » Tue Aug 10, 2004 1:17 pm

Sounds like you have a missing or leaking check valve. The check valve in the vacuum line from the intake down to the front cross member resevoir ensures that the reservoir stays at the maximum vacuum at idle and does not drop as the manifold vacuum drops under power wit the throttles open.

The head lights going up as you accelerate shows that the vacuum in the reservoir is dropping. You most likely have a leaking check valve or its missing if the system was in bits before you assembled it.

Rohan
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PostPost by: brassrngfm » Tue Aug 10, 2004 5:21 pm

Rohan is right about the check valve. When I rebuilt my Elan, I changed the original setup to a failsafe setup. After some driving, the internals of my checkvalve vibrated and actually unscrewed so that it was no longer functional. I got just the symptoms you mentioned. On my checkvalve (aftermarket from Tingle's), I was able to unscrew the end and use a screwdriver to re-set the actual needle valve to it's proper position. I still have a slight leak in the headlamp valve itself, which causes the headlamps to raise after I shut off the engine.
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PostPost by: rickf » Tue Aug 10, 2004 5:51 pm

You can get an inline check valve from www.napaonline.com for $3.99 USD.
Cheers,<br>Rick<br>1972 Elan +2
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PostPost by: Hamish Coutts » Wed Aug 11, 2004 7:56 am

Had similar trouble just after I got my +2. Check valve was OK. Solution was:
- replace all the T pieces and elbows (some had split in at the angle). SJ Sports Cars will send you new ones.
- there is also a joint down at where the plastic piping joins the vacuum piston (the one that operates the headlamp mechanism). In my car the rubber had softened and was being colapsed by the vacuum. Result - slow headlight drop.
- replace the black plastic piping. Some dork had tried to do a repair with electrical tape! It leaked - obviously. Headlights only stayed down for a few minutes after the engine was switched off. I used 8mm copper pipe.
- the solenoid was sticky and wouldn't operate at lower than 12? volts. So nothing happened at tickover or below 1500 revs. SJ Sports Cars supplied a new one.

Everything works fine now and the headlamps stay down for a week if I don't run the car. By the way, you can also get all the components from Christopher Neil. If you are in the States, sorry can't help you with a supplier.

Best of luck,

Hamish.
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PostPost by: Hamish Coutts » Wed Aug 11, 2004 8:07 am

Just thinking of the title of this discussion.

Anybody remember the halcion days of the 60s when Elans were new? There was one guy who owned a boutique in Carnaby St in London who had an Elan where the headlight mechanism worked separately on each headlight. The purpose - to make the car wink because he had eyeballs painted on the lenses and I think he even had eyelashes fitted to the headlight cowls.
I remember as a racing purist being horified at this. Seems as much a laugh now as John Lennon's flower power Mini Cooper Ss.

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PostPost by: chiltern5 » Sun Aug 15, 2004 2:34 pm

I also had problems on my +2 with the headlights coming up on their own and only staying down for about 5 mins after turning off the engine, after removing the pipe from the manifold and conecting a low pressure airline it turned out to be only a loose jubilee clip on the vacume cylinder, result they now stay down for more than twelve hours.
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PostPost by: neillav » Mon Aug 16, 2004 3:48 pm

Many thanks all. The non-return valve is missing so I've just ordered one from Christopher Neil. Hopefully that should solve things and small children will no longer laugh at me...
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