Bleeding the Brakes
This job may be necessary if you have removed any major brake components such as the Master Cylinder, the calipers or wheel cylinders. I had to do it after I had the brake switch replaced. When something is removed from the closed hydraulic brake system, the system is no longer sealed, and air is allowed in. This causes air bubbles in your brake fluid. After the part is replaced it is vital that the air is removed, otherwise you will have problems when you go to slow down the car, and it won't.
Things that are your Beetle's way of telling you he/she needs the brakes bled include 'brake fade', the situation where your brake pedal sinks to the floor and your still rolling… fast!
This process should be carried out every two years as a form of preventative maintenance for your own safety. Its not too hard, more a bother than anything, but I guess you'd feel that way after having to do it over three times in one day like I just did!
I know of two ways to carry out this job, the first is the tedious one, but it requires the least parts. The second is quite easier, you can do it alone, but you will have to get your hands on a few more tools to complete the job.
1. METHOD
Notes:This is a job to be carried out by two people.
You will need clear, plastic tubing.
A 7 mm spanner.
A glass, which is partially filled with fresh brake fluid.
Procedure:
2--Your partner must be in the driver's seat to control the brake pedal.
3--Jack up one side of the car, and starting from the furthest wheel from the master cylinder (i.e. on right hand drive cars, start at the left rear wheel, for left hand drive start at right rear wheel) locate the nipple or valve on the upper part of the backing plate. The nipple should have a rubber cap on it. Take this off, but don't lose it.
4--Now lock the spanner over the nipple, push the tube so that it fits over the 'spout' and place the other end into the half filled glass of brake fluid.
5--Tell your partner to "pump" the brake pedal. Seeing as there was probably something wrong with your brakes to start with, the pedal should easily sink to the floor with every push. The pumping is creating pressure in the system. After a few pumps, tell your helper to "hold it" in, meaning to hold their foot down on the brake pedal. At this point you should use the spanner to open the nipple bleeder, which will cause the old brake fluid to come running out down the tube and into the glass. What you are looking for here is the discoloured old brake fluid and air bubbles. This process is aimed at removing both from the brake system. After the pressure is lost and there is little fluid running out, tighten the nipple bleeder and get your partner to pump the pedal again. You should continue this process till there is visible fresh brake fluid running out, and no more air bubbles can be seen.
6--Tighten the nipple, replace the rubber cap, you didn't lose it did you? And move on to the next farthest wheel from the master cylinder. You work that one out. You may want to check that there is a suitable amount of brake fluid remaining in the reservoir; it may need a top up after each brake is bled. If there is not enough fluid in the reservoir and you continue all your efforts will be in vain as this will allow air back into your system, therefore defeating the purpose of this procedure.
Brake fluid, excluding those that are silicon-based, will have a nasty effect on your nice paintwork.
Glycol-based fluids attack and strip paint, so take care to clean up any spills that may occur, as this is a major cause of rust. You may also want to put down some cardboard or similar around where you will be working to keep spilt fluid from staining your workshop/garage/driveway cement.
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