A fundamental problem with the vacuum extraction type of brake bleeder such
as the Mity Vac is that they rely on an air tight seal around the threads of
the bleeder screw to achieve a vacuum seal. My experience with these is
that this is very hard to get, most of the time, so that the vacuum jar gets
bubbles on every stroke, and you never know when the lines are clear of air.
I have an expensive (Snap-on) commercially made brake pressure bleeder, but
I've found it just as convenient to supply pressure to the reservoir
directly from my air compressor, with the regulator set to 30 PSI to
overcome the check valve in the master cylinder, and just bleed off fluid
until I see clear new fluid coming down into the jar. I have to stop and
top up the master cylinder each two wheels or so to avoid drawing in air,
but that is a small price to pay for a perfect bleed every time. I have one
spare master cylinder cap for each of the types I have worked on, with the
vent holes plugged and a motorcycle type (metal screw in) tire valve
installed. My air hose chuck has a latch-on type tire chuck, so I just
clip it on the cap, set the pressure, and off I go, merrily riding around on
my creeper!
Dick Benjamin
----- Original Message -----
From: "mike sutton" <mikanlin62@xxxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Tuesday, March 18, 2003 6:09 PM
Subject: Re: IML: Brake Bleeders
> In a word about Mity Vac's , as far as brake bleeding: THEY SUCK! And no
> pun intended either. They are great for checking vacuum advances, heater
> controls or actuators, lots of vacuum operated or controlled devices. We
> never had the degree of success with mity vac bleeding that we did with
> pressure bleeding.
>
> This was over the course of several years, bleeding brakes on cars,
trucks,
> industrial equipment....anything with hydraulic brakes. One problem is
that
> with a mityvac, you have the potential problem of pulling air into the
> system as well as pulling brake fluid from the master cylinder. Another
> difficulty is getting some of the mity vacs to work as well if you
> inadvertently get brake fluid into it.
>
> We used a pressure bleeder that was nearly identical to the garden sprayer
> type that was mentioned earlier. It was a commercial pump and canister,
and
> a 0 - 15 psi gauge on it, a shut off valve, and a length of hose and
adapter
> that was made up to attach to the fittings that were installed on the
> various master cylinder covers we had for the different master cylinders
we
> worked with.
>
> The one caveat with these , or any pressure bleeder - dont let the fluid
> level get too low or you just went from pressure bleeding to pressure
> aerating in a very short time.
>
> Have fun
>
> Mikey
> 62 Crown Coupe
>
>
>
Back to the Home of the Forward Look Network