Lotus Elan

Headlight vaccuum non return valve - or lack of it!

PostPost by: RichardS » Sun Mar 01, 2009 5:14 pm

I'm reconnecting the vacuum piping for the headlights [non fail safe]and don't think I have the non return valve in the circuit. Looking at the parts book there should be a valve in the line from the inlet manifold to the T piece. There isn't one in my current vacuum circuit as far as I can see - the set up is as it was when I last drve the car in the 1980s and I never had any problems with the lights popping up and down then!

Is the non return valve a safety feature to reduce the risk of losing the vaccuum and thus the headlights popping down? Would it be sensible to fit one? Sue Miller lists them at ?37 - is there a cheaper non lotus non return valve that would do?

Thanks

Richard
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PostPost by: SADLOTUS » Sun Mar 01, 2009 5:34 pm

I used one of these before I went electric

http://cgi.ebay.co.uk/8mm-Fuel-one-way- ... 240%3A1318

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PostPost by: paddy » Sun Mar 01, 2009 6:50 pm

There definitely needs to be a non-return valve; otherwise the headlights will just droop whevener you put your foot down.

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PostPost by: dlbarnes1 » Sun Mar 01, 2009 7:02 pm

I would recommend a Swagelok B-2C4-1. Check www.swagelok.com for availability in the UK. This valve is less expensive than what is normally listed for an Elan. It is a high quality industrial component that has provided years of leak-free use for me.

Dave 72 Sprint DHC
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PostPost by: alexblack13 » Sun Mar 01, 2009 7:21 pm

Hi All / Richard,
Are you sure it is not there? It lives in the brass connector that screws into the inlet manifold. Try giving it a 'sook'. You should be able to 'sook' one way but not the other.

Give it a try. Go for a good 9 on the 'sookometer' and don't swallow the bu***r they are dear to replace. :lol:

Alex 8)
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PostPost by: RichardS » Sun Mar 01, 2009 7:59 pm

Alex

I think you have the answer! I nearly unscrewed the brass bit this morning to give a trial suck but was mislead by the parts diagram which suggests that the valve is in the line. This would explain why it worked fine previously!

had a good morning seesion today - braided fuel hoses now in place! Engine fire up getting closer.

Richard
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PostPost by: alexblack13 » Mon Mar 02, 2009 8:19 pm

Looking forward to seeing it next time down. I am in Stoke this thursday but going by train (which I hate!)

:? :?

Keep up the good work... :)

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PostPost by: Rob_LaMoreaux » Tue Mar 03, 2009 1:46 am

When I first got my car it was in pieces, so as I put it back together I thought it didn't have a non-return valve. I got a cheap one from the local parts store and put it in line with the brass fitting. That worked great. Well when I changed engines I went to move the brass fitting since the other engine did not have one and I discovered it was a non-return valve, that just didn't work very well. So I kept the cheap diaphragm one and the headlights went most of this winter without popping up (failsafe system).

So while the brass one is there it might be good to add another one to make it better.

Rob
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PostPost by: john.p.clegg » Tue Mar 03, 2009 6:16 am

Two do work better than one....at a certain revs (when thrashing it) my headlights used to droop....took me ages to find the problem...seems the valve would leak at certain revs (vibrations/frequencies/harmonics?) and fitting another inline cured the problem....as it is highly unlikely that the two would have the same resonant frequency...

John :wink:
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