TheSamba.com :: View topic - bleeding brakes...not sure what im doing wrong.....

Thu Nov 05, 2009 8:24 am

I swapped out my master brake cylinder on my 73 Westfalia and tried to bleed my brakes but seem to be doing something wrong....when i start in the rear, loosen the bleeder screw, almost no fluid comes out at all. I have tried using a self bleeder bottle with no luck and the help of a buddy. still nothing. Do i need to be using a vacuum bleeder? Is there something that i am missing?
Thanks in advance for your help Samba crew....

Thu Nov 05, 2009 8:26 am

You need to bleed the master cylinder itself first if you have not done so yet.

Thu Nov 05, 2009 8:27 am

Perhaps your rear rubber flex hose is bad or clogged?

Or is the wheel cyl not replaced? Used wheel cyls often have clogged bleeder screws. Take the screw all the way out and see.

Thu Nov 05, 2009 8:28 am

I opened up both lines feeding into the master cylinder and let them drip for 5 or so min's. Is there another way to bleed the master?

Thu Nov 05, 2009 8:30 am

Rear wheel cylinders are about 200 miles fresh...

Thu Nov 05, 2009 8:31 am

MCBAIN wrote: Rear wheel cylinders are about 200 miles fresh...

Okay what about that flex hose. When you put that wheel cyl on 200 miles ago with the old master did it bleed off okay then?

Thu Nov 05, 2009 8:35 am

Bench bleeding the M/C will help a lot. Some say it isn't necessary, but I've always done it. It sure does save a lot of pumping and bleeding if the M/C is already full. Others say that you should start up front first after replacing the M/C when dealing with front discs and rear drums. You'll hear a lot of different respones and opinions about all of this.

Thu Nov 05, 2009 8:35 am

Found this info in another thread:

Quote: You do not need to remove the master cylinder to bleed
close all bleeders and gently pump the pedal 6-7 times and hold it
down.then open the brake line @ the m/cylinder that goes to the REAR ONLY. the pedal will sink a little.Close the brake line and repeat until you feel the pedal getting firmer.

then go to the right rear and repeat this a couple times
then the left side. and make sure to check and refill the resovoir as needed.

From this thread, which addresses the same issues you're having:
http://www.thesamba.com/vw/forum/viewtopic.php?t=292097&highlight=bleeding+master

Thu Nov 05, 2009 8:38 am

Flex hose....not sure where my flex hose is....
and the system did bleed fine after the wheel cylinders were replaced.
I didnt do the work but the bus stopped fine for about 200 miles. At that point the brake pedal started slouching and I noticed i was having to pour in a significant amount of fluid but no visible leaks. Pulled the master and felt inside the booster and it was full of fluid. Swapped it out and here i am.

Thu Nov 05, 2009 8:39 am

Keith asks pertinent questions regarding the replacement of the rear cylinders, you should have seen some fluid come out of the brake lines once they were removed.

Thu Nov 05, 2009 8:41 am

OHHHH, you have a roached Booster now if it's full of fluid, bummer is that the fluid can return to the engine through the vac line if it's that full.

Thu Nov 05, 2009 8:41 am

Definitely sounds like your master needs to be bled. Either take it off and bench bleed it, or try bleeding it while on your Bus as stated above.

bench bleeding:
http://www.thesamba.com/vw/forum/viewtopic.php?t=93598&highlight=bench+bleeding

Your booster may be toast, too, if it's full of fluid.

You have a flex hose at each wheel, it goes from the central metal brake line to each wheel cylinder. It's rubber so it can move up and down with the suspension.

Thu Nov 05, 2009 8:46 am

Since my booster was full, is it toast? I got most of the fluid out, not every last drop but the majority. Do i need to pull it and completely clean it out before proceeding?

I will definitely try bleeding the master per the description

and my flex hoses are new...thanks for the explanation of what my flex hoses are.

Thu Nov 05, 2009 8:53 am

I would think that removing the fluid from the booser is not fixing the problem. Could be wrong. Wasn't there a thread not long ago highlighting someone who rebuilds those?

Thu Nov 05, 2009 8:56 am

i thought i was fixing the problem by replacing the master. The master was leak in the first place.

Thu Nov 05, 2009 9:00 am

I said I could be wrong. I would bench bleed the master and go from there. When I replaced the master on my bug I ran into the same symtoms and was hard headed about pulling it out to bench bleed it. I did bench bleed it and they bleed in no time at all.

Thu Nov 05, 2009 9:40 am

I was just asking about the flex lines etc to get more detail as the problem can be caused by several things.

I do like to "wet the whistle" on the bench on new masters, it's not really a true "bench bleed" with as many open ports as these masters have on them before install.

You should try cracking the lines at the master and let them drip a few seconds and it will take a good # of pumps to push the air out all the way to the rear.

As far as the fluid in the booster, I have seen them survive being filled with fluid. It just depends on how long it's been leaking into the booster before you noticed and got to it.

I'd say roll with it but put rebuild or replacement on your list.

Thu Nov 05, 2009 9:43 am

Cool...thanks for all your help guys.
I will give this all a go tonight and let you know how it goes.

Thu Nov 05, 2009 10:00 am

Here is the address of the place that rebuilds them. They do it cheaper than any NOS or new booster I've ever seen.

If the fluid was not in there for months or years you might be all right, but who knows for how long. And they can only "suck" the fluid in through the vac line to the intake if the diaphragm ends up with a hole in it/fails or rusted guts get a hole from the corrosive fluid/moisture sitting for a good while.

Karl wrote: Take it off and send it to:

H & R Automotive Parts
10328 Oakwood Dr
Dallas, TX 75217
972-286-5516

Thu Nov 05, 2009 3:52 pm

Bleeding air from the MC while it's installed should be fairly quick and easy. It has been on mine. One thing that might be involved in it not working or not being a quick job is bleeding the back first. Bentley say front first. I do front first. It's a one man job. A helper is nice but not needed. Nor is pressure bleeding or other goodies needed.