Anyone who’s done a brake job knows that the worst is saved for last. Bleeding the brakes can be a time consuming, frustrating job.
Most use the two man procedure of having one person pump the brakes while the other works the bleeder screws. Others use the vacuum pump method, squeezing that little hand pump until their hands cramp with fatigue.
There is another option, pressure bleeding. The principle is simple. You pressurize the hydraulic system, open one end and let the fluid run until all the air is forced out.
This has not been a viable option for the hobbiest due to the high cost of most of those units. Some can be as much as $500.00, although more inexpensive options are available.
For a cheap guy like me, that was out of the budget. My solution? Build it myself! Follow along as I give you the step by step on how you can build a pressure bleeder for under $25.00.
The first step is to gather the parts you’ll need. I purchased a half gallon garden sprayer at my local hardware store for $14.00. The ¼ inch hose nipple, castle nut and washer were in my spare parts bin. The plate is some scrap 1/8 inch metal but you could easily use plexiglass or wood for this. You will need some type of gasket material. I had cork on the shelf but some type of rubber might be more durable. You’ll also need a hose clamp or clip to hold the hose to the nipple along with some RTV sealant.
Remove your master cylinder cap and trace an outline on your cap material. We are using a scribe since we are working with metal. Cut the plate slightly larger than the outline. You’ll want it to overlap the master cylinder edges to get a good seal.
Since this car used a GM dual reservoir with a smaller back chamber than front we need to determine the center of the smaller chamber. This way we’ll know where to drill the hole for the nipple. In this instance it was determined to drill it 1 inch from the edge. We do this on the smaller chamber to center it. We can then pressurize one chamber, bleed it, swap it around end to end and do the other chamber.
Mark your plate for drilling using the measurements from the master cylinder. Center the mark so that the plate will overlap the master cylinder edges and seal well.
Drilling the hole is pretty straight forward. The threaded end will need to protrude through the plate. With a ¼ inch nipple you’ll need a ½ inch bit. The nipple you select will depend on the size of the feed hose on the sprayer.
The next step is to glue your gasket material to the plate. I chose to use Permatex weatherstrip adheasive that I had handy. Any type of contact cement that will hold the gasket material to the plate material could be used. Remember, you’re dealing with brake fluid so be sure it will stand up to the chemicals. I use DOT 5 silicon fluid so I was felt confident they weatherstrip adheasive would hold up. Get the glue out to the very edge of the plate. This will keep the gasket material from peeling back.
After sticking the rim the gasket material to the plate, trim the hole for the nipple. Apply RTV to both sides of the plate to make an air tight seal. We found out after the fact that a washer on BOTH sides works better.
Trim away the excess gasket material.
Cut the wand from the hose using a sharp set of wire cutters or a box cutter. Shove the end of the hose onto the nipple and secure it with a clamp.
Here’s our finished pressure bleeder. All that’s left is to put in a quart of brake fluid, attach it to the master cylinder securely and pump it up. You don’t need a lot of pressure, 15 to 20 pounds will do the job. I found that about 10 pumps did the job for me.
Here it is in place on the car. A large C clamp is used to seal the plate to the master cylinder. This could also be done with an inexpensive ratchet strap. NOTE:A word of caution. I found that the C-clamp doesn't seal the lid like it should and I pumped some fluid out around the edges of my MC that ran down to the floor. No biggie for me since I run the DOT5 fluid that doesn't eat paint but others should be aware of this. I'll be trying it with small ratchet straps the next time to spread the pull down force evenly. Another option is to used a much thicker metal plate for that cover. This would keep it from flexing under the clamp and leaking out around the edges.