Old, dirty brake fluid can reduce the effectiveness of your truck’s brakes. To ensure your brake fluid is clean and free from moisture, air, and dirt, it is important to occasionally flush your old brake fluid and replace it with new fluid. You can do this at home on your Silverado or Sierra by following these steps for making a simple DIY brake fluid pressure bleeder.
Tools & Materials Needed to Make a Brake Pressure Bleeder
- Standard garden sprayer — The type used for spraying fertilizer and nutrient solutions.
- 3/8” x 1/4” diameter clear vinyl hose — Approximately 10 feet will do.
- 1/8” NPT to ¼” hose fitting – To use to attach your hose to the brake fluid reservoir cap.
- 1/8” female NPT coupling – To help make the reservoir cap airtight
- A 1/8” flat washer — To go between the fitting and coupling.
- Master cylinder reservoir cap for your Silverado or Sierra — Consider Dorman part #42042.
- Reservoir cap gasket — To ensure a good seal for your pressure bleeder.
- Silicone gasket sealant — RTV or similar for sealing your threaded hose fitting.
- 5/16” and 3/8” drill bit and drill — for making a hole in the cap.
- A small hose clamp — to secure the hose to your bleeder.
All of these together typically cost under $25. Once you’ve built your pressure bleeder, you’ll need the following tools to bleed the brakes on your Chevrolet Silverado or GMC Sierra pickup:
- A new bottle of brake fluid — always start with new, sealed containers of brake fluid. An opened bottle can absorb moisture and air, rendering your brake fluid ineffective.
- A basic turkey baster (or similar tool) — For removing the old fluid from your master cylinder.
- A 10-mm wrench — For loosening your bleeder valves.
You probably have most of these things laying around the garage; however, we suggest you purchase a new sprayer since any water or dirt left in your old sprayer can contaminate your brake fluid.
How to Make a Brake Fluid Pressure Bleeder
While you can find brake bleeder kits for sale in auto parts stores, we have a cheap and easy alternative. Almost any inexpensive garden sprayer you’ll find in a garden center or hardware store will work for this project. Aim for one gallon or smaller, since you won’t need more than two or three quarts of fluid.
If possible, choose a sprayer with a pressure-relief valve. This makes it easier to remove the pressure in your sprayer when you’re done. The purpose of your pressure brake bleeder is to pressurize the brake fluid in the sprayer and force it through your brake system. Make sure you follow all the instructions for making the bleeder airtight.
There are two major tasks to be done: One is to create the pressure cap that installs on the master cylinder reservoir, and the other is to attach this pressure cap to your sprayer.
Start with your pressure cap assembly:
- Drill a hole in the middle of the new brake fluid cap using the 3/8” drill bit — we recommend starting with a 5/16” pilot hole to avoid cracking the cap.
- Remove the rough edges and plastic flashing around the drilled hole and thread your hose fitting into the hole — this will be a snug fit.
- Apply RTV sealant to the inside of the cap/hose fitting before installing the washer, more RTV sealant, and finally the 1/8″ coupling to create a leak-free threaded assembly.
- Cut a small hole in the center of the cap gasket so it fits over the coupling and allows your cap to seal against the brake fluid reservoir of your truck when screwed into place.
- Remove the hose supplied with the garden sprayer by unscrewing the fitting over it and carefully slitting the hose and pulling it off the 1/4″ hose barb fitting that comes with the sprayer — this hose it is not compatible with brake fluid.
- Use the original hose fitting that comes with the sprayer to attach your clear 1/4” hose to the sprayer — it simply installs in place of the original hose.
- Assemble the sprayer according to the original instructions — screw the pump and handle into place in the top of the sprayer body.
- Attach the free end of your clear hose to your pressure cap assembly by sliding the hose over the fitting on the cap and tightening it in place with the hose clamp.
Now assemble your pressure bleeder:
Your brake fluid pressure bleeder is now ready to use. It’s important to use enough RTV sealant to fully seal your pressure bleeder because any leaks can allow air bubbles to enter your brake fluid. This can cause spongy brakes. Follow the drying times on your RTV sealant. We suggest making your brake bleeder the day before you plan to bleed your brakes so it can dry overnight.
Tip: If there is a prominent ridge or seam on the inside of your new reservoir cap you may want to smooth this out with RTV sealant and let it dry completely before you attempt to drill into it to make the hole for the hose fitting.
How to Bleed Your Brakes
Once your pressure bleeder is completed, it’s time to put it to work. While a sprayer with a pressure gauge can be useful (to create approximately 20 psi of pressure), it isn’t necessary. If your brake fluid stops flowing, you can always pump your sprayer again to create more pressure.
Follow these steps to attach your pressure bleeder to your braking system and purge the worn and contaminated brake fluid from your brake lines:
- Fill your sprayer with two to three quarts of clean brake fluid.
- Remove your existing brake fluid reservoir cap.
- Suck out as much of old the fluid using the turkey baster.
- Fill your reservoir to the top with new brake fluid.
- Tighten your new pressure cap in place.
- Remove the wheel at the corner you’ll be bleeding first.
- Remove the cap from the bleeder valve and install a section of clear 1/4” hose over the valve nipple. Place the end of the hose in a clear bottle to catch your old brake fluid.
- Loosen your bleeder valve with a 10mm wrench until your brake fluid starts to flow.
- Pay close attention to the color of your old brake fluid so you’ll notice when the clean fluid flows.
- Once you see only clean fluid and no air bubbles, tighten your bleeder valve and replace the cap.
You’ll need to perform steps 7 to 10 for each wheel.
Tips for Bleeding Your Brakes:
- We suggest starting with the front brakes and finishing with the rear, as this ensures you eliminate all old brake fluid and air bubbles from your master cylinder and brake lines.
- If you jack up the front of your truck and remove the tires you won’t have to pause for as long between bleeding your front brakes. Then do the same for the rear.
- Brake fluid can mark paint and isn’t great for the environment, so avoid getting it on your truck or the ground.
All that’s left to do is remove your pressure bleeder cap from your truck, verify the level of your brake fluid and replace the original cap. You’re ready to hit the road again and harness the full braking power of your Chevrolet Silverado or GMC Sierra.
Do you have any tips or tricks for bleeding your brakes? Let us know in the comments below!