Remote brake servo fitting.

[Gmg31]

I’ve just installed a remote brake servo and the moment I start my engine the brakes come on and the wheels a locked. I’ve connected pipe from the master cylinder to the side of the servo and the pipe from the end of the servo to the 4 branch union. Is it possible I’ve done this the wrong way round?

[Pfreen]

I assume you have a Lockheed booster.  If so, you have it plumbed correctly.  It would seem the air valve or air valve piston is stuck.

I hope the diagram helps.

[4129R]

Do the brakes release if you disconnect the rubber suction pipe from the inlet manifold?

[shortjedi]

I seem to remember there is supposed to be locking device fitted to the filter/ valve for shipping. Mine didn't have one.  Be careful when removing the plastic cap, there is a spring inside.

[jbcollier]

Use the diagram above to see which way the pipes are fitted.  Usually fitting them backwards means no brakes.

Is this a new or rebuilt booster?

[Gmg31]

It a second hand one. I may have made an error in trying to save a few pounds. Duh

[jbcollier]

I have overhauled a few boosters (10 or so?).  I have also fixed other people's overhauls.  One chap fit a valve backwards so the booster actually pushed back rather than assisted.  Now that was a firm, but remarkably ineffective, pedal.  They eat up a lot of time to overhaul so we got to the point of only fitting new ones.  It was much cheaper than all the work that is involved in overhauling a 40+ year old original.

[Gmg31]

Thanks JB. I’ll have a look at that valve before I decide what to do. Clearly the vacuum part is working well so I don’t want to make a hasty decision.

[Gmg31]

I took the cap off the top of the valve. The valve doesn’t come out so I’m assuming it can’t be upside down. However within the cap was a plastic collar which, as far as I can see would only serve to block any escaping air. Not sure if it’s meant to be there.

[jbcollier]

When you apply the brakes, fluid pressure pushes the valve up shutting off engine vacuum and allowing atmospheric pressure in.  The "filter" keeps muck from getting in.

[Gmg31]

In the photo it looks like a soft felt filter but it’s actually hard plastic.  I’m guessing this is my most likely problem.

[jbcollier]

Nope, sounds right.