Re: 4kq - Brake pressure regulator

[Andrei Talalaevskii <andrei@grad.physics.sunysb.edu>]

>
> The brake pressure regulator on my '84 4000sq is leaking and needs to be
> replaced.
>
> Q1 - Is it possible to temporarily plug the lines as I remove them, or will
> I get brake fluid all over the place and have to bleed the master cylinder
> and clutch anyhow?
>
>

If you have a brake line extension about 30 cm long, it is possible to
connect lines so that they bypass a pressure regulator.

1. Connect one of the front outlets of master cylinder directly to the
line that goes to the passenger front wheel. Originally this line is
connected to the pressure regulator and the second front outlet of mc is
originally connected to the line that goes to the driver's front wheel
(leave it intact).

2. connect one of the "rear" outlets of master cylinder to the line that
goes to the rear brakes. (the other rear mc outlet is plugged)

You will need an extension for Step 1 because the line won't reach the
cylinder. For step 2 you would only need to disconnect the line from
pressure regulator and connect it to master cylinder.

After that the pressure regulator will be totally removed from the
circuit. You can take it out or drive with it in place until you get a
new one. The pressure reg is expensive! You might want to try to rebuild
yours yourself. I have never done that but heard that it is possible. If
you choose to buy it, shop around!

Of course, this is a temporary solution and drive very carefully
especially on slippery road until you replace your pressure regulator.
Also, do not engage the center differential lock until your pressure
regulator is back.

You will have to bleed the brake system after that but not the clutch.


> Q2 - How much more would be involved if I wanted to remove the master
> cylinder so I could repaint the brake booster (lost some paint due to
> leaking brake fluid.)  Bentley manual seems to indicate that I would have
> to remove the booster and master cylinder together anyhow?
>

I don't understand why repaint the booster, but removal of mc from
booster is trivial. Two same screws hold both mc and the bracket of
pressure regulator to the booster.

> Q3 - I do not have a pressure bleeding setup, Can the master cylinder be
> pedal bled if it has run completely dry?
>

I use a pressure bleeder made from a thick-wall plastic bottle with two
holes in the cap, misc. couplers, PVC tubing and the tube from the
bicycle pump that is screwed on a spare tire. All these are available
from many catalogs for about $20 total. There has been a discussion
recently on commercial setup by "Gunsen" (sp?). Maybe other lister can
advise on it. It is the most effective method of bleeding, reduces the
required manpower to 1 person. Also, according to bentley, clutch can
only be pressure-bled.

HTH,

Andrei.

Golf & 4kq.