Brake Bleeding 1967 Bus

[spiffy]

Ran into a little snag tonight while bleeding the brakes. The drivers side rear tire would not cough up any fluid even while pumping the brake pedal.

What could be causing this?

1. Gunk in the line/nipple?
2. Symptom of a cylinder gone bad?

The other three nipples flowed freely.

[vwlover77]

Could be....
1) Gunk in the master cylinder (or other problems there)
2) Gunk in the line.
3) Pinched line
4) Gunk in the wheel cylinder or bleeder

How did the fluid look coming out of the other cylinders? How much of the old fluid did you get rid of during the bleeding (hopefully all that you could)?

[spiffy]

The fluid in the master is all clear and nice.

The crap that came out of the nipples looked like pigeon crap...so we pumped them until it was mostly clear.

So it sounds like I need to look at my hard lines and cylinder and possibly the bleeder.

I was trying to avoid 'airing' out the whole system but it sounds like I may have that task to tackle.

[Amskeptic]

The fluid in the master is all clear and nice.

The crap that came out of the nipples looked like pigeon crap...so we pumped them until it was mostly clear.

So it sounds like I need to look at my hard lines and cylinder and possibly the bleeder.

I was trying to avoid 'airing' out the whole system but it sounds like I may have that task to tackle.

A lot of air in the system can cause a semi-vapor lock. Top off the reservoir and open the bleeder screw and leave it open with a little hose going into your anti-air bottle at the wheel cylinder. Go find something else to do. Gravity will usually allow the fluid to displace enough air to let you get somewhere with the bleeding process when you return. Always allow plenty of slow and deliberate brake pumps between bleed screw openings, and give the system time to replenish the lines. . . this only occurs when your foot is off the brake pedal. A number of impatient people crack the screw open too much, pump the pedal too quickly, and wonder why pressure never develops.
Colin

[vdubyah73]

Internally collapsed flexible line on that wheel, or W/C full of pigeon crap.

Bill

[RSorak 71Westy]

Yea if the other 3 bleed ok the problem is close to/ in the wheel that didn't. 1st completely remove and inspect the bleedr screw then the hose.

[hambone]

I'm about to replace the MC on the Beetle, found this good advice on S*mba from Drscope. Never done it this way but worth a try:

One thing to be aware of is the corrosive paint killing nature of brake fluid. This stuff gets on your hands and then gets transferred to everything you touch. Try to keep your hands clean, or else in a few months, you will have places that you touched where the paint is doing funny things.

When you are done bleeding, it is also a good idea to flush away any fluid that got on the car with a hose.

One of the things I don't like about bench bleeding is the mess it makes on the bench. Be careful where that stuff is squirting to. It usually has a way of making to the car cover for your 100 point show car!

Anyway, here's a few pointers that might help...

First adjust all the shoes out. If they are not adjusted, you won't be able to bleed properly.

Make sure your pedal pusher is NOT in a hurry! They must use slow steady strokes. If they get going too fast, it will aerate the fluid filling it with millions of tiny bubbles that can take days to come back to the surface.

Dual master cylinder likes to have the fronts bled first. If you don't do that, sometimes they can't build enough pressure to get the rears to bleed.

If you have had the system open (new lines, new wheel cylinder, or new master) here is something that may help.

Understand that air is compressible. Brake fluid is not. If there is a lot of air in the lines, sometimes you just don't have enough pressure to push it out. It just compresses and doesn't move along.

Fill your reservoir. Go the Right rear. Open the bleeder and have your helper push the pedal and hold it down. Close the bleeder. Have the helper let the pedal up. Open the bleeder. Have them push the pedal DOWN AND HOLD IT. Close the bleeder. Have the helper let the pedal up. Open the bleeder. Have them push the pedal DOWN AND HOLD IT.

Do this several times or until you start to get fluid out when the pedal is pushed. Then go to the left rear and repeat the process. Then the right front, then the left front.

When you have good flow at all 4 corners, then go back to the traditional, pump a few times, hold the pedal down, open the bleeder, close the bleeder, pump a few times, open the bleeder......

[spiffy]

Yeah, that's a really helpful write up. I gonna try that.

Thanks Hammy! Nice lookin' out