Kasey: Yes, if you have a bubble of air trapped in front of the
working end of your switch, the air will compress but you will not
have enough pressure exerted to hydraulically move the switch
diaphragm. Overtightening is possible but usually results in
stripped threads and leaks, not inoperative switches. Also, no
teflon thread or pipe compound should be used because it can
interfere with a good ground for the switches.
I have changed master cylinders for over 25 year on bugs and have
never done what I'm about to suggest: bench bleeding. In this
procedure, the MC is held in place in a vice and brake fluid is
dripped into the MC with a toothpick, one drop at a time, then the
switches are installed. Someone who has actually done this can give
you more specifics and details but that is the basic idea.
As for brake bleeding, it's not that complicated of a task, and is
highly recommended (and absolutely necessary if you remove the MC).
So now you've filled the MC as full as you can get it on the bench,
you've filled the switch ports with fluid and installed the
switches, and you've reinstalled the MC. Now get a helper and go to
it. The fluid reservoir should be full and care given that it
doesn't run dry. Start at the right rear wheel; put a small wrench
(7 or 8 mm?) on the bleeder; put a short piece of plastic tubing on
the bleeder, and the other end into a jar filled with a little
fluid...this is so air is not drawn back into the brake lines; Have
your friend pump the brakes and hold them down; crack the bleeder
open and watch the fluid be forced out, then tighten the bleeder. Do
you see bubbles? Repeat until you don't see bubbles. Tighten the
bleeder (not too hard, or it will strip right off). Now go up and
check the fluid level in the reservoir. Repeat process for left rear
then right front, then left front CHECK fluid level after each whee!
Get used to this process; it should be repeated (completely flushing
the old brake fluid out) every couple of years or so. Failure to do
this results in moisture collecting in the system (brake fluid is
hygroscopic..i.e. it loves water) and causes pitting and other
corrosion to occur. If this seem like too much to tackle, go to one
of the major national repair shops (but NOT to Brakes Plus if you
want my opinion) and ask them to bleed the system for you. Good
luck. And you have checked the fuses and the bulbs? Clancy
kasey wrote:
>
> Please disregard my last post because I have definitely traced all
> the wires going in and out of my master cylinder. the lines going
> in have power, and i have directly put power into the lines going
> out and the brake light work fine. i have just paid $10.00 for 2
> brand new brake light switches and installed BOTH of them...but my
> brake lights still do not work do not work do not work!!!!!! could
> there be a pocket of air in the master cylinder that's keeping these
> switches from operating properly??? if so, how can i get the air out
> (besides bleeding all the brake lines)??? Could I have
> "over-tightened" the switches when I screwed them in (and
> potentially froze something inside)? Finally, can someone tell me
> if they've also run into the problem of 2 new switches that don't
> work??? thanks.
>