Vacuum Canister Diaphragm - Concern About Leaving Pods Down?

[elanern]

All,

I just finished completing work on the headlight vacuum system - 1970 Federal S4 fail-safe with single canister. I repaired the one-way valve, which was the source of the only vacuum leak. Prior to the repair the pods would stay down for only a few seconds after I shut the engine off. Checking each vacuum circuit identified the valve as the leaker.

The two-piece valve has a rubber seal between the hose adapter and the main body. Replacing the seal (cut from a spare piece of rubber) and then resealing the assembly with RTV I've now got a vacuum system that is extremely robust. The headlight pods have remained closed for several days now, which, looking through the archives, seems to be acceptable.

My question is, what sort of stress does leaving the headlights in the closed position place on the canister diaphragm? Is it better if the car will sit for some time to open them up, thus relieving the canister of stress? Or doesn't it matter in terms of canister longevity?

BTW, I was surprised that the headlight switch still seals, having read many tales of failure with no readily available replacement.

Thanks for your comments.

[Frank Howard]

what sort of stress does leaving the headlights in the closed position place on the canister diaphragm?

None really. I think you are worrying about something that is not a problem in the first place. On an Elan, there are plenty of other things to worry about.

[rgh0]

I dont think the lightds staying down all the time causes any problems in terms of pod life or function. My plus2S 1230/5 has the failsafe system and they will stay down indefinitely ( the longest I had without using the car was when I was doing a GB rebuild a few years ago and they stayed down for over six months OK).

The system is orginal except for the check valve to the vaccuum reservoir and nothing else has needed replacement in 35 years. The check valve that holds vacuum so well is a $1 plastic body unit I picked up and replaced the orginal rubber disk in it with a polished Australian 1 cent cupro nickel coin.

cheers
Rohan