vacuum cylinders, early Plus 2

[bill griffiths]

I am working my way through the failure of my headlights to "pop up", the engine only having been started recently after an extensive rebuild.
Some vacuum exists in the front chamber after the motor has run at various revs for about a couple of minutes.
The front chamber has passed the test of holding pressure after applying compressed air.
My recollection from an earlier identical car is that it took little time for sufficient vacuum to build up to raise the pods.
Non return valve mounted on front manifold.
No obvious leaks.
No physical impediment to the pods opening.
Springs correctly installed.
Tube to off side cylinder removed and blocked.
Similarly, vacuum pipe to booster blocked off. (This comes via a non return valve from the rear manifold.)
Operating valve removed from dash and the two tubes joined. One runs to the near side cylinder, the other to the T at the front of the resevoir. I don't see it matters which is which.

I am now grasping at straws!
When I checked the parts diagram, I noted that the failsafe cylinders all have different numbers.
My car is non-failsafe. I am wondering if they are different, and If I have been supplied with a pair of the failsafe variety! Might that be relevant?
The cylinders were supplied new, and have sat, installed, for a couple of years.
Any thoughts of something I have forgotten?
Regards,
Bill

[oldelanman]

Operating valve removed from dash and the two tubes joined. One runs to the near side cylinder, the other to the T at the front of the resevoir. I don't see it matters which is which.

Bypassing the valve will certainly eliminate it as a cause of your problem but it does matter which way round the pipes are connected. When pulled out to raise the headlamps the inlet and outlet ports are simply connected together but when pushed in to lower the headlamps the vacuum supply from the reservoir is closed off and the pipe to the actuators is opened to atmosphere. Reverse the connections and the reservoir will be vented and the engine will "see" a continuous vacuum leak.

You seem to have checked most things but have checked the lamp pods are moving freely when you raise them manually ? They may be siezed on the pivots. That will also check that the actuator diaphragms are moving freely.

As your actuators are new they are unlikely to be leaking but if you want to eliminate that possibility you can do a simple check without removing them from the car. Disconnect the vacuum pipe(s) from the actuator, raise the headlamp manually to expel the air then blank off the port(s), the pod should stay up if there is not a leak. Off the car you can do the same test by suspending the actuator and hanging a weight from the pull rod.

[bill griffiths]

Dear Roger, Thanks for your assistance.
After the test you suggested to check the vacuum cans, one stayed up all night...and the other one
failed entirely.
I purchased both new about 3 years ago and my own fault for not checking them earlier. They have been installed for about 2 years but were only put to the test last week when I first started the new engine.
I can find no information about whether, unused supposedly from new, there is any way to improve their (lack of) performance.
Perhaps viagra?
Regards, Bill

[oldelanman]

Hi Bill,
It does seem odd that a new actuator should fail so soon.
Assuming the early Plus 2 is basically the same set-up as the 2 seater, the LH actuator has 2 ports ...did you blank them both when doing your test ? Just a thought !
Regards,

[alan.barker]

I have done a repair for a small leak by using a Puncture Repair pressurised canister.
Use some rubber tube and connect to the Vacuum Unit. You have nothing to loose
Alan