The Hydraulic brake booster is located behind the Brake master cylinder on
the Fire wall in the engine bay.
What happens is that the front main
seal in the unit gets worn out and Power steering fluid runs past it and finds
its way through the grub screw on the bottom of the unit, and then it drips on
to the chasis rail and then manages to make it way to under the wheel archs and
make a big disgusting mess.
What we are doing is fixing this
problem...it is not to difficult and rewarding.
First you have to
depresurize the brake system! pump the brake pedal 20times with the engine off.
Now you have to remove the Master cylinder, this task is tackled in the
link below..follow that and come back here.
Brake Master cylinder replacment HERE!
Also while you have all this crap off your car....you may consider also
replacing all those delapitated Power steering hoses..find it here:
First you will need to buy a seal for the Hydraulic brake Booster.
I
bought mine from Steve Haygood in the US, for about a $1 or something, i cant
remember
If your here in Australia ordering a seal from the US for a $1 is Not worth
the bother.(but if your buying a new MC from there get it at the same time.)
So here are the dimensions of the seal (ask for a O-ring) which you
should be able to take down to a bearing/engineering supplies and provide you
with the exact same seal photo below:
The Red dot one is the NEW seal and the Yellow dot is the Old seal. (or
O-Ring)
You can see a visable diffrence between the thickness of the old
seal compared to the new one...the Old one when you ran it through your fingers,
felt eliptical rather than round...it is hard to think that what looks to only
be a small diffrence can cause such a messy leak.
The Dimensions for a
New seal are as follows:
Outside diameter: 44mm
Inside diameter:
37mm
Thickness of rubber: 2.5mm
Now i measuered it with a
Micrometer and it should be very close to what i have stated, but it is
difficult to measure something accuratly made of rubber.
Firstly a photo of the leak you are trying to fix!
In the photo above you are looking from underneath the Brake booster, where
you see the Red fluid (power steeing fluid) that is the leak.
The Fluid
finds a path past the Seal and follows down the Grub Screw (Retaining screw) and
drips constantly.
So you should have your Master cylinder off by now,
and be looking at this:
Now you have to push the Black plastic part of the Brake booster in, then
undo the grub screw that is not meant to be undone. Sounds easy yeh?
It
is.
Get your 2 old Brake Master Cylinder bolts and find some suitable
washers that will go just over the black plastic part on each side of the brake
booster as pictured below:
Now screw in the bolts till it retains the black plastic sleeve and has
pushed it back a touch so as to make removing the Grub Screw Easier.
Now
remove the Grub Screw, you will need a pair of Vice grips as the grub screw is
supposed to be tamper proof....but not IDIOT proof :)
If you looked at
the Brake Master cylinder write up, you may have noticed a handsome set of Vice
grips there that would do the job perfectly..buy some.
Ok, with the Grub
screw removed, the only thing that is stopping the giant spring located indside
the Brake booster is the bolts with the washers retaining it.
Undo the
bolts untill they are near the end of there thread...but dont leave it till the
last thread!!.
Now push your hand on the black plastic sleeve (no need
to touch the Metal bar in the middle of it at all)
You should be able to
push it in a little.
Now get a helper to remove the bolts !!!!BUT DONT
LET GO OF THE PLASTIC SLEEVE!!!
Now let the Plastic sleeve out slowly
till all the tension is gone.
Some power steering fluid is going to pour
out..not a big deal.
It should look like this:
No need to go pulling out the whole Spring....... there is no need to, so
dont disturb it.
Just remove the black plastic sleeve at the front of
the spring and you will have this:
The photo above is the spring with the Black plastic sleeve removed. The photo below is what the black plastic sleeve looks like when removed from the Spring, this is where your $1 seal goes...at this stage i should mention one of these units will cost you about $600 plus from the dealer. so a theoretical saving of $599 id say...i bought some beer with the change.
Just replace the seal with your new seal where the old seal sat on the ridge
of the plastic sleave.
There is another seal around the metal bar in the
centre, that can also be replaced and i cover it in the link below (i do NOT
reccomend you do it though), also there are alot more seals deep inside the
Brake booster, if you want to know more and delve deep into the booster, i cover
the operation here:
Brake Booster Overhaul (Not available)
But if the Power steering fluid leak is the only problem then you should be
fine with just the one main seal.
It is the same as pulling it apart except that you have to line it up.
Put your black plastic sleeve with the new O-Ring (Seal) onto the
Spring.
Try and line up the Plastic sleeve as close as you can to the
grooves and grub screw retianing hole before pushing the spring back in.
Use your palm and push the Spring back in, while holding it in, get your
helper to put the Brake master cylinder Bolts with the Washers back into the
Brake booster to retain it, once they are in you can let go and it should be
retained by the bolts.
Hopefully it is still i roughly in line. slowly
do up the Bolts until the grub screw hole is viable through the plastic sleeve
at the bottom (refer 2 photos above).
If it is not inline, just loosen
the bolts off and try and twist it into the right spot, if that does not
work...take it off again and start over and try and line it up again.
(i
actually ended up taking it and having another shot at lining up, it took me
about 4 goes to get it right)
When it is in line, put the Grub screw
back in and tighten.
You can remove the bolts with the washers and it
should stay retained.
Put your Master Cylinder back on.
Now you
should be able to retain a nice clean engine bay. Good Luck.
