Brake booster test

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11th July 2016, 11:55 AM
Throbbinhood

Quote:

Originally Posted by Bigcol

snip...3 pumps on the pedal, holding pedal on the third pump - let the fluid out - pedal goes to floor, mate locks bleeder nipple, pump again, and again and again
(I always go for 3 or 4 times per wheel, until new clean fluid is coming out )

Put something behind your brake pedal Dom. If you push the pedal to the floor, the piston will be travelling further than normal and you could damage a seal etc if there is any pitting there. Fwiw, I've used a vacuum bleeder before and it worked well for me.

EDIT: Didn't see this in your last post Dom, which mirrors what I've said above.

Quote:

Originally Posted by Bigcol

snip..ALWAYS start at the nipple furthest away from Master Cylinder
so
passenger rear
drivers rear
passenger front
drivers front

The brake bias valve has been left out of the above and must be bled. From what I remember reading, it should be done first. Then PR, DR, PF, DF.
11th July 2016, 02:19 PM
dom14

Quote:

Originally Posted by Throbbinhood

Put something behind your brake pedal Dom. If you push the pedal to the floor, the piston will be travelling further than normal and you could damage a seal etc if there is any pitting there. Fwiw, I've used a vacuum bleeder before and it worked well for me.

EDIT: Didn't see this in your last post Dom, which mirrors what I've said above.

The brake bias valve has been left out of the above and must be bled. From what I remember reading, it should be done first. Then PR, DR, PF, DF.

True. I think the vacuum bleeder is worth the money you spend on it. Master cylinder is way too expensive to damage it.

Does the bias valve has a bleed nipple?
11th July 2016, 07:39 PM
Bigcol

some do, some dont

depends on what yours looks like Dom
11th July 2016, 07:42 PM
Bigcol

Quote:

Originally Posted by dom14

True. I think the vacuum bleeder is worth the money you spend on it. Master cylinder is way too expensive to damage it.

a proper Vacuum bleeder is the correct way

the cheap and nasty one with a ball bearing in the end of a tube from Supercrap is shyte
11th July 2016, 11:20 PM
pearcey

G`day Guys
Bleeding the system with a new or recon master is a simple job but needs two people.
One on the pedal and one at the wheels. doesn`t really matter which where you start , but first bleed the master. Fill the master and REPLACE the cap,person on the pedal pushes pedal to floor (do not bang the pedal down, just push it down easy) only once, holding pedal down. person on the spanners cracks the pipes at the master, once air and fluid stop flowing retighten tube nuts, now person on the pedal releases pedal SLOWLY over a time of around 5 seconds. DO NOT pump.Repeat until all air is expelled and only fluid comes out.WARNING the fluid does squirt all over the place so a cover of rag and plenty of water around is necessary. IF the fluid gets on paint work wash it off strait away with flowing water.. OK master bleed now to the wheels, dosen`t matter where you start but farthest away is not a bad place to start. Person on pedal pushes pedal down and holds it down, spanner man opens bleeder and waits until air and fluid stops flowing, shut bleeder then person on pedal, SLOWLY "5 seconds "releases pedal,then waits another 10 second before pushing pedal to floor again. Repeat until only fluid comes out at the bleeder. Repeat process at each wheel and then you should have a good hard pedal.DO NOT bleed brakes with the engine running. Now with a reasonably amont of pressure on the pedal start the motor and the pedal should drop a small distance, this indicates that the booster is working.
If there is a bleeder on the load sensing valve bleed this before doing the rears.
OK reasons for NOT pumping pedal. the seals in the master are designed to collapse when the pedal is released and any air in the reservoir side of the piston will be dragged into the pressure side, but releasing it slowly gives the reservoir side time to recover, once the system is air free it can operate at any speed. The same problem happens with drum brake system where when bleeding, a quick release of the pedal can and will draw air into the wheel cyls especially if they are old. Another thing I do is to clamp of all the hoses apart from the wheel being bled, this stop back and forth movement of fluid apart from the wheel being worked on. WARNING DO NOT CLAMP BRAIDED HOSES.
Hope this is of some help.
12th July 2016, 01:57 AM
dom14

Quote:

Originally Posted by pearcey

G`day Guys
Bleeding the system with a new or recon master is a simple job but needs two people.
One on the pedal and one at the wheels. doesn`t really matter which where you start , but first bleed the master. Fill the master and REPLACE the cap,person on the pedal pushes pedal to floor (do not bang the pedal down, just push it down easy) only once, holding pedal down. person on the spanners cracks the pipes at the master, once air and fluid stop flowing retighten tube nuts, now person on the pedal releases pedal SLOWLY over a time of around 5 seconds. DO NOT pump.Repeat until all air is expelled and only fluid comes out.WARNING the fluid does squirt all over the place so a cover of rag and plenty of water around is necessary. IF the fluid gets on paint work wash it off strait away with flowing water.. OK master bleed now to the wheels, dosen`t matter where you start but farthest away is not a bad place to start. Person on pedal pushes pedal down and holds it down, spanner man opens bleeder and waits until air and fluid stops flowing, shut bleeder then person on pedal, SLOWLY "5 seconds "releases pedal,then waits another 10 second before pushing pedal to floor again. Repeat until only fluid comes out at the bleeder. Repeat process at each wheel and then you should have a good hard pedal.DO NOT bleed brakes with the engine running. Now with a reasonably amont of pressure on the pedal start the motor and the pedal should drop a small distance, this indicates that the booster is working.
If there is a bleeder on the load sensing valve bleed this before doing the rears.
OK reasons for NOT pumping pedal. the seals in the master are designed to collapse when the pedal is released and any air in the reservoir side of the piston will be dragged into the pressure side, but releasing it slowly gives the reservoir side time to recover, once the system is air free it can operate at any speed. The same problem happens with drum brake system where when bleeding, a quick release of the pedal can and will draw air into the wheel cyls especially if they are old. Another thing I do is to clamp of all the hoses apart from the wheel being bled, this stop back and forth movement of fluid apart from the wheel being worked on. WARNING DO NOT CLAMP BRAIDED HOSES.
Hope this is of some help.

Hi Pearcey,
I've been wondering. From what I've heard so far, bleeding the master cylinder is very important to make sure the brake's are working properly.
Yet, there's no bleed nipple on the master pump. It's not that easy to bleed the master pump without making a mess, even when bench bleed it.

Why haven't they put a bleed nipple on them? I'm wondering!
12th July 2016, 02:01 AM
dom14

Quote:

Originally Posted by Bigcol

a proper Vacuum bleeder is the correct way

the cheap and nasty one with a ball bearing in the end of a tube from Supercrap is shyte

How about this one?

http://www.ebay.com.au/itm/Brand-New...4AAOSwstxVTgGF
12th July 2016, 02:18 AM
dom14

Quote:

Originally Posted by Bigcol

a proper Vacuum bleeder is the correct way

the cheap and nasty one with a ball bearing in the end of a tube from Supercrap is shyte

I just realized, a cheap bicycle pump or a balloon pump with a long enough transparent vacuum hose attached to it,
is also a good makeshift vacuum bleeder.
12th July 2016, 09:33 AM
pearcey

G`day Dom.
Yep bleeding the master is a bit messy, but it`s only done once every few years , not like changing the the oil filter every 6 months.
Only problem with brake fluid is it removes paint in a very short time, hence plenty of water.
Bleed nipples on the master are an added expense that serves no real purpose so the factory leaves them off.
There are a few older cars and trucks with them but these are on masters that are very hard to get at and would have made bleeding at the factory a lot easier and less time consuming (which equals money saved)
12th July 2016, 11:02 PM
dom14

Quote:

Originally Posted by pearcey

G`day Dom.
Yep bleeding the master is a bit messy, but it`s only done once every few years , not like changing the the oil filter every 6 months.
Only problem with brake fluid is it removes paint in a very short time, hence plenty of water.
Bleed nipples on the master are an added expense that serves no real purpose so the factory leaves them off.
There are a few older cars and trucks with them but these are on masters that are very hard to get at and would have made bleeding at the factory a lot easier and less time consuming (which equals money saved)

Yeah, the brake oil leak from the master cylinder has ruined the paint on the brake booster and the body, which has caused rust as well. I had to respray the whole area with metal care paint to avoid any further damage.
I understand the master cylinder get bled once every few years, but that's enough to damage the paint if I drop some on the paint.
Yes, of course, plenty of wet rags should prevent from brake oil getting onto the paint.

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