Bypassing the vacuum headlights

[Ross Robbins]

In his sad story Elan vs. Rock, Andrew Bodge wrote: "The nylon pull rods that work my (electrically actuated) headlights"

This caused me to think about a thread on how to replace the vacuum system on my Plus 2. There is a slow leak that makes them rise like a ghost on long uphill or hard acceleration periods. I assume the process is the same for replacing the mechanism on bot Elans and Plus 2's so here it is in TIC.

Who has a solution they can photograph and share?

[AussieJohn]

Your problem may only be the non-return valve; maybe worth a look.

[peterako]

I second the non return valve suggestion.

I added one in-line (additional to the one on the intake manifold) to mine.

Belt and Braces

Also, there may be a leak from your vacuum reserve.

Do your lights stay down when the car is sitting parked (engine off)?
They should, for at least a week.
If they don't the lights are relying on a continually produced vacuum from the engine to stay down.

Mine stay down more or less indefinitely with the engine off....but it took a bit of work....including the introduction of a new vacuum reserve.

There is a detailed thread on this forum about putting in an electric motor solution. So a quick search should throw this up.

Best of luck,
Peter

[gerrym]

The symptoms you describe definitely point at the non-return valve. If this valve is not working, the vacuum in the headlight system will float off the engine vacuum...when this is minimal such as full throttle, there will not be enough vacuum to keep the headlights in position.

Reasons why the non-return valves fail include soaking from petrol (eventually causes the elastomer to soften) and/or blockage with debris.

Easy enough to check out the non-return valve with a Mity pump. Then you know what to fix/replace.

Regards
Gerry

[RotoFlexible]

There is a good thread on electrical headlight actuation (with lots of photos) here. Actuators are easy to come by on ebay, from Celicas or Mazda Miatas/RX7s.

[paddy]

The symptoms you describe definitely point at the non-return valve.

I'm not sure I agree.

A failed non-return valve will result in the lights drooping directly in line with a drop in manifold vacuum, ie as soon as you put your foot down.

The symptom described (ie a slow droop when vacuum is low) I think does just indicate a leak somewhere (which could also include the non-return valve, but could equally be elsewhere). The leak will cause the accumulated vacuum to fall, and this will cause the lights to droop slowly whenever the vacuum reservoir is no longer being replenished continuously (so you will see it if manifold vacuum is low for any extended period).

Paddy

[leifanten]

Paddy,
would that not depend on if you have fail safe or non-fail safe mechanism? On a fail safe the lights would come out when you lose vacuum, on the non fail safe, they would drop when you lose vacuum?

[paddy]

would that not depend on if you have fail safe or non-fail safe mechanism? On a fail safe the lights would come out when you lose vacuum, on the non fail safe, they would drop when you lose vacuum?

Yes, I was thinking of non-failsafe.

Paddy

[Ross Robbins]

Thanks to all for the responses. I have been away from the computer for a day or so due to a work trip.

I will check the non return valve but I think Paddy is right that there is a leak somewhere we have tried diligently to staunch and have not been able to, hence the request for the electric alternative. The lights are fail safe and stay down for about 10-15 minutes after I switch off. If I am driving gently they stay down but as soon as I move more briskly they start the rise/fall pattern and when I really get after it they are just up all the time.

Thanks for the link Andrew. It is exactly what I was looking for.

[RotoFlexible]

This thread got me thinking about going back to the vacuum system. The electric actuators work fine (except when I crash ) but I always felt slightly guilty about abandoning an original system that can be made to work. With everything out of the nose and all the mounting holes about to be glassed over, it's a good time to pursue this project.

So, I hauled out the old vacuum components and, with the aid of a Mity Vac, leak tested them. The pods are fine. The switch leaked a lot, especially in the "lights up" position. I took it apart, cleaned up and greased the rubber valve and the surface it slides on, and added a thin shim to make up for wear. Now it's as good as new. The check valve (that screws into the manifold) is shot and will have to be replaced.

That leaves the reservoir. The car's at the body shop so I can't check it, but when the frame was out a few years ago, the welder who reinforced it for me found and welded the leaks in the reservoir. I'll test it when I get the car back, just to be sure.

Next step is to clean up and paint the pods, I guess.

[kstrutt11]

I fitted a TR7 motor to mine many years ago, which still works OK, basically you just replace the pod with a motor and make a link rod up (2 small rose joints and some threaded rod).
If I remember correctly there was a bit of fiddling around to get the crank on the motor at the right angle and matching the lengths of the cranks.
The only other problem I have had is it doesn't seem to have enough power to raise / lower the lights when the engine is off, A more modern motor such as the Mazda ones should be much better for this.


Kevin