How to Bleed the Brakes on an Aircooled Volkswagen Beetle
One of the most important steps to make a bug's brakes safe for use is to properly bleed the system. Any time the brake system has been open, such as to replace the master or wheel cylinders, it is critical to bleed the brakes before the vehicle is driven.
1 Assemble tools and supplies:
New brake fluid.
A clear container partially filled with brake fluid.
A length of 3/16" tubing.
A box-end (usually 7mm) wrench.
The stock is 7 mm; if wheel cylinders have been replaced it's possible that the valves are 1/4-inch or 5/16-inch.
2 Ensure the brakes on all four wheels are properly adjusted.
3 Remove the master cylinder reservoir cover and check the level and condition of the brake fluid.
If it is dirty or filled with debris, replace it with good fluid.
Make sure the reservoir is filled to the horizontal seam.
Reinstall the cover on both the reservoir and the bottle.
4 Begin at the wheel the furthest from the master cylinder, the right rear wheel, loosen the bleeder valve slightly then snug it up so it can be loosened quickly and easily.
The bleeder valve is below the bolt for the wheel cylinder and above the hard brake line.
It should be covered with a small rubber grommet.
5 With the box wrench on the valve, place one end of the tubing firmly over the bleeder valve and submerge the other end in a small quantity of brake fluid in a clear glass container.
Have the assistant pump the brakes slowly a few times to get pressure in the system, then depress the pedal firmly and hold it down.
While the pedal is depressed, open the bleeder valve just enough to allow a flow of fluid to leave the valve. The brake pedal will sink. Watch for air bubbles to exit the end of the tube submerged in the brake fluid.
Close the valve and have your assistant slowly return the brake pedal to its normal position.
6 Repeat the steps until no more air bubbles appear in the container and clean bright colored fluid emerges from the valve, then tighten the bleeder valve.
7 Move to the left rear wheel, then move to the right front wheel and end with the left front wheel. Be sure to check the fluid level in the master cylinder reservoir frequently.
8 At the end of the operation refill the master cylinder reservoir to the horizontal seam.
Be sure to check the fluid level in the master cylinder reservoir frequently during the bleeding operation.
Add fluid as necessary to prevent the fluid level from falling low enough to allow air bubbles into the master cylinder.
After every wheel, more often if there is a lot of air in the system.
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