Erratic headlamp pop ups

[M.J.S]

I was driving my recently aquired 72 Elan +2, last night, for the first time in the dark. The headlamps popped up and worked no problem for the few miles to a friend's house. I put the headlamps down and switched the engine off after a few minutes running.

When I came to leave and fired her up, the headlamps refused to pop up again, no matter what I tried. After I while I drove home on sidelights and after a few hundred yards the lights suddenly sprang half way up and then over the next few minutes bobbed erratically up and down, seeming to adjust with the throttle.

By the time I was home they were fully up and retracted again when I switched them off. I haven't touched the car since.

I have noticed that when the car is left unused the lights do slowly begin to raise themselves up about half way after 3 or 4 days, which I assume is a leak or a weakness in the vacuum system somewhere. But the erratic up and down show is a new one on me.

Any ideas from you experienced +2 owners please?

Thanks.

[memini55]

The headlights on a +2 are a safety type setup to pop up with no vac. The intermittent action while motor running on our +2 was from binding on the pivot points. I took the large spring off and tried to manually move thru the motions. All the pivots where somewhat stiff and I lubricated everything with spray silicon and adjusted the sideways clearence. They have worked well ever since.

Mark

[ppnelan]

If the one-way valve on the inlet manifold is not working, it will respond to throttle openings as the vacuum changes.
Could also be the vacuum switch/valve (if an early car) or electrically-operated solenoid valve (if it's a later car)...
There probably isn't a serious vacuum leak if they stay down for 3 or 4 days - that's good in my experience

Matthew