Vacuum brake bleeder set up

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by: Cobalt327, Crosley, Foperfoauto, Jon, Triaged
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Contents

[edit] Overview

These instructions will allow a person to successfully vacuum bleed a hydraulic brake or clutch system.

[edit] What is needed:

  • Vacuum pump
  • Glass jar with lid
  • Clear tubing
  • Brass fittings
  • All this should cost around $20

[edit] Vacuum jar

Most any jar can be used; the one shown is an old spaghetti sauce jar with drilled holes in the lid and some brass fittings in it. Use rubber washers to get a tight seal. Using a canning jar like made by Ball or Mason will work well; they have a lid insert with a rubber seal.

Complete lid and jar assembly
Underside of lid showing details

[edit] Fittings

Shown being used are 3 male 1/4-NPT x 1/8 barb fittings, 1 female 1/4-NPT x 1/8 barb fitting, 1 female 1/4-NPT x 1/8-NPT coupler, and 1 female 1/4-NPT 90° fitting. Also put a ball valve on the pressure input side. The valve is needed to control the vacuum.

[edit] Vacuum pump

There are several brands of hand held vacuum pumps available. The most recognised is probably the Miti-Vac unit.

You can also get inexpensive venturi (need an air compressor to operate) vacuum pumps made for AC work from Harbor Freight. The vacuum fitting is 1/8-NPT on the other side.

Miti-Vac bleeder kit p/n MV8500
Pneumatic Venturi type vacuum pump similar to what's sold by Harbor Freight

[edit] Warnings

There are a few issues with vacuum bleeding. First is sucking air around the bleeder valve threads. The solution is to use Teflon (PTFE) tape or Teflon thread sealer on the threads. If some air leaks past the threads this isn't much of an issue as long as mostly brake fluid is in the bleeder hose. Throttling down the vacuum pump also helps.

Be sure to keep an eye on the fluid level in the master cylinder reservoir as it will go down quickly. If you are flushing out old brake fluid use a turkey baster (that will never be used on food again) to remove the old brake fluid from the reservoir. Refill with fresh fluid before resuming bleeding.

Warning Warning: Most brake fluid will severely damage painted surfaces if exposed for long. Remove and wash using a lot of clean water and mild soap, rinse clean.
Warning Warning: If you are using engine vacuum for bleeding the brakes, then this means the engine is running . Anytime the engine is running unattended by a driver, chock the wheels, put the transmission in Park and/or set the parking brake. Good ventilation is essential!
Warning Warning: Be safe: If the vehicle is raised off the ground, use jackstands and chock the wheels, use Park and parking brake as needed.
Warning Warning: The only thing (chemical) that should ever make contact with brake fluid is the same type of brake fluid.

Also see Health and safety in the shop or garage.

[edit] How to use the venturi-type vacuum pump

Hook up a hose from the brake bleeder to the fitting on the jar with the short piece of hose inside the jar. Hook the other fitting on the jar to the vacuum pump. Hook up the vacuum pump to your compressor. A ball valve can be used on the compressor side to throttle down the amount of vacuum.

[edit] Using a hand held vacuum pump

Leave the engine bay alone, go to an auto parts store and buy a hand-operated vacuum pump that includes all the fittings needed to bleed a hydraulic system, or from Amazon.com, etc.: Cost is about $30 made of plastic resin, $35 for the brass version, ca. 2012.

Regardless of the type of vacuum source used, remember to vent the master cylinder by loosening the cover. If you leave the lid locked down when you are trying to bleed, the fluid won't flow.

[edit] Using a syringe

A large syringe (30–100cc) can be used to draw out the fluid. These syringes do not have needles and are disposable.

[edit] Alternative vacuum source

This might not be 'recommended' by the auto manufacturers, but engine vacuum has been successfully used instead of a pump. No compressor or pump is required, just the jar and some hoses. If using the engine as a vacuum source, do make sure you are using manifold vacuum at the sourcing port and not ported vacuum.

Make sure to connect directly to intake manifold vacuum (below carburetor or throttle body), do NOT go through any valves,solenoids, etc. that may be damaged if brake fluid enters them (although the jar should prevent that).

If you do get brake fluid past the jar and into the engine, a little bit won't hurt, just STAY AWAY from the exhaust pipe! Burning brake fluid STINKS!!!

Not recommended for diesels because they have a vacuum pump, normally with a rubber diaphragm. Brake fluid could damage it.

[edit] Tips

Another tip is to use clear tube from a home fix-it store (Ace, Lowes or Home Depot, etc.) or the pet (fish) section of a discount store. The clear vinyl will snuggly fit over the tip of the bleeder; you can see the air bubbles. The pet section should also have the petcock valves designed to go into the clear vinyl, check back in the fish section. Its all cheap and disposable.

You can also remove a vacuum reservoir from a salvage car and use this reservoir as a portable source, use the clear tubing, and the petcock to open and close the line. You can then charge this with manifold vacuum, close the line and then shut off the engine before you start the repair of the brakes. This way you have portable vacuum without having to keep engine running.

Always bleed the brakes from the furthest point from master cylinder first. The master is typically on the driver side firewall so you would bleed in following order: passenger rear, then driver rear (refilling the master cylinder as needed), then bleed the passenger front and then the driver front. At conclusion check the fluid level, button up the tires, torque the lug nuts to spec, remove the stands, drop the car, and then check pedal position, pedal travel and then test drive.

For rear drums you will need to reset the star adjuster prior to the road test, this is easy to do if the vehicle is equipped with self-adjusting rear brakes by driving in reverse and consistently lightly stabbing the brakes. This lets the star adjuster set the proper distance between the shoe facings and the drum.

[edit] Bleeder screws

You can use fresh bleeder screws to make pairs of brake bleeders with the tubing already securely attached to keep with the bleeder set up you have. Many bleeders are metric threads; all GM made prior to 1982 should be SAE; Ford and MOPAR is a toss-up; most cars after 1982 should be metric.

[edit] Also see:

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