Interesting???.very interesting

[bcmc33]

When speaking to Classicar Automotive who is refurbishing my busted servo, I was told that the diaphragm had been virtually destroyed by petrol. The root cause is very common to the Elan due to the servo being being in the nose and below the manifold connection. (The +2 wouldn?t suffer with this potential problem).

Apparently, over time, petrol vapour in the vacuum pipe will turn to liquid at the lowest point and eventually work it?s way into the servo. I am told that the remedy is to put a ?U? bend in the system to collect the liquid when it forms which will then be sucked into the manifold on start-up.

So I plan to have the non-return valve in the servo pointing upwards so that the pipe can loop up and then drop down to the floor of the nose below the servo before routing it?s way around the radiator up to the manifold.

I guess an alternative would be to have a non-return valve on the manifold as per that fitted for the vacuum headlamp actuators.

[oldelanman]

Hi Brian,
That's a good tip. How deep would the U bend need to be do you think? My vacuum pipe already slopes down from the servo elbow then runs across the floor of the nose before rising up past the rad to the manifold so the lowest point of the tube is about 5 inches below the servo connection. Do you think that's sufficient?

When I rebuilt my servo there was a lot of gunge in the can which seemed to be mainly brake fluid but I guess that's to be expected after 38 years !

[bcmc33]

From what I can remember, Roger, I think my car was the same as yours. The pipe as it ran across the nose was defintely below the servo inlet, but I guess not by much, and I'm sure the non-return vale inlet was horizontal.
The advice was for a "U" bend in the system, and that's why I shall have the non-return valve pointing vertically so that when the pipe runs across the nose the simulated "U" bend will be about 6" deep.
I may also put a non-return valve in the pipe close to the manifold - as belt & braces approach.

[Elanintheforest]

I was just reading an old Girling manual, where it says that all seals and vacuum hoses must be replaced at 40,000 miles or 3 years. I'm sure that we all stick to that little maintenance tip!

Mark