I bought a Mighty Vac last year to trouble shoot the vacuum system on my
C***v*tte. These are neat little devices and I have used it for many
things since then. They are especially handy if you own a newer car with
vacuum controlled devices.
I bought the one that includes the vacuum gauge and would highly recomend
this one over the model without the gauge. They also build a steel version
that is even more expensive. Mine is plastic, works great and cost me 35
bucks at Big Wheel.
I have never used mine to bleed brakes, prefering to get my SO involved int
this process. For general brake bleeding tips, I offer the following:
1) Do not let the master cylinder run dry during the process. If it does,
you have to start all over again.
2) When you have to bleed you brakes, go all the way and change the brake
fluid. I would use DOT 4. Ford brake fluid is supposedly the hot tip in
racing circles as it is the same as some name brand racing fluid at a much
lower price.
3) Soak your bleeders with wonder goo before trying to loosen them. The
longer you can do this the better. I would consider replacing the bleeder
screws if they are fairly old. They are usually fairly cheap and few
things are more agravating than breaking one off.
4) If you aren't getting fluid out of the bleeder, I would first suspect a
clogged bleed screw. I have had this problem many times over the years.
Remove the screw completely. If that doesn't help, I would work from the
master cylinder out, loosening joints to find the blockage. Soak these
with wonder goo, also. Use a brake line wrench (looks like a six point box
wrench with one side cut out. The brake line nuts can freeze in two ways.
They can freeze into the caliper / cylinder / junction and be impossible to
loosen. This will be obvious. They can also freeze onto the brake line
flange. You will be all happy that the nut starts turning only to notice
that you have twisted off the brake line after a couple of turns. This
really sucks. If all you want to do is burp the line at the junction,
sometimes you can get it loose enough even with the nut frozen to the brake
line flange but be careful! Replacing brake lines is not my idea of a good
time.
5) If none of this works, you probably have a problem in the master
cylinder. For some MC's, you can clear a clog by gently forcing brake
fluid backwards thru it with a syringe. This may not work on some due to
residual pressure valves. The brake pedal must be completely released to
do this.
6) I none of this works, try it again. Hydraulics can be finick and
sometimes it just takes time to work a stubborn bubble out. Also, some
service centers can pressure bleed systems.
7) If in doubt, replace the part. I have had my brakes fail 3 times over
the past 25 years. Only once was there an actual accident involved,
(totaled a Saab 96 on the back of a Caddy on my way to the Florida Keys.
Bent the licence plate on the Caddy) but it is very dangerous and can also
cause loss of body function control.
8) Finally, concerning using a Mighty Vac to bleed a hydraulic system,
remember that suction relies on good seals. If the brake bleeder is rusty
or loosened too far, air can get in instead of brake fluid. Try removing
the bleeder and coating the threads with anti-sieze to seal them. Also try
cleaning the head of the bleeder to promote a seal with the attachement
tube.
Good luck and happy braking
Bill Eastman
61 MGA with working hydraulics when stored this fall
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