Headlight lift mechanism - right delayed

[makepeace]

Hi all,

My 76 Elite's right headlight takes quite a while to pop up when compared to the left. Probably around 10s. The roadworthy centre marked this as being a problem.

Anything particularly I should check and any way of solving this or is it expected behaviour? I mentioned to them that they are vacuum operated and that this sort of behaviour could be expected, and it seems like they might give me a pass for it, but would like to try if there is anything that can be done. 

[Escape]

The vacuum is used to pull the headlight pod down, it pops up with a spring. So I'd have a good look at the linkage and spray some lubricating oil on the hinges and pivots, that should help things.

[exeterjeep]

I had to replace one of the solenoid valves, I could hear it sucking when the engine was running. May be the valve is sort of sticking to release the vacuum. Very early cars had 1 valve fitted to power both lights but later ones had a valve in under each of the headlamp/pods. Getting at them is a bit restrictive as you have to take the headlight out and work through the aperture.

[Angus553]

Having worked on my vacuum headlights several times. I found the best way to remove the system was to undo the bolt at the bottom of the vacuum and the 2 retaining bolts at the top of the unit thus giving access to everything. One point to note is when undoing the 2 top bolts a knee and hand  on the headlight pod keeps everything in place whilst the unit is withdrawn as when the 2 bolts are released the unit pops up instantly!! Having also broken my solenoid valve and fixed it,it then chose to work faster than the other one and having tried everything to re sync them as it was annoying me,(made the decision to fit MX5 motors instead.)  Having taken everything out and fibreglassed the rusted out vacuum pods and lubricated the relevent parts it worked much better but the lights just wouldnt synchronise. Replaced some pipe work and used jubilee clips on all the joins as well.

[Dion]

On 22/11/2021 at 10:55, exeterjeep said:

Getting at them is a bit restrictive as you have to take the headlight out and work through the aperture.

Seems my 1975 Elite had an inspection cover in the panel under the bumper (but the panel lid is missing from my car). Curiously only on the RH side. Anyhow the headlamp mechanism is very accessible when the front bumper is off as there are large holes behind the bumper.

[Tony D]

Sounds like a dodgy solenoid valve to me. 

When the valve changes state, it has to drop the vac to atmosphere. If the piston in the valve doesn't fully move, there'll be a restriction, making response slower. 

Any openings behind the bumper are bodges done by previous owners I'm sure. 

Tony 

[makepeace]

So I removed the pod and took everything apart and lubricated etc. Same story after reassembly. Next is to remove both and compare and then possibly look at a replacement solenoid. Thanks for the suggestions all!

[exeterjeep]

If you find it easy to get at both solenoid valves you could try switching them around, to see if the problem changes sides?

[makepeace]

Running out of time with this, which prompted me to think of an improvement to this system.

What if... One paralleled the two lines going to each solenoid, ie, connect the two actuators, and the two sides of the vac system with some extra pipe and t pieces. This then gives some redundancy and will also synchronise the two pods in every way other than the actuators and springs.

Thoughts? Is there a hole in this concept?