Heyyaa
One of the more important and most overlooked items of maintenance on our HDs, is the system’s Brake Fluid. Our brake system on the HD isn’t the best when new, so we need all the help we can get to extend the life.
Many people will drive their truck for years with the original fluid. Even when installing new linings, they’ll still ignore the fluid. Yet, in only 18-24 months, your brake fluid’s boiling point can drop as much as 200 degrees.
Today I flushed the system’s brake fluid, took some pics along the way, and wanted to share. You’ll need 2 quarts of fresh DOT-3 fluid.
There are many techniques used, and since I have an air compressor, I chose to use this kit from HF for $30.
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Brake Fluid Bleeder
If you don’t have air, they have a manual pump for le$$. Either of these will be much better than having to yell at your Brother-in-law to mash the brake pedal.
Brake Bleeder & Brake Bleeder Vacuum Pump Kit
We’ll start at the Master Cylinder. Remove the bleeder valve adapter from the end of the suction line and insert to drain the old fluid.
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Go ahead and dump the reservoir into your used/recycle oil container, readying the pump for the next step. This is what the old fluid looks like.
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Fill the Master Cylinder with fresh fluid and ready the kit’s fill bottle. Here, we have a clean MC with fresh clear fluid, you can see to the bottom now.
![Image]()
Select the appropriate sized adapter for the auto refill bottle. The bottle has a ball valve to keep closed until in position and ready to start, and then open. This functions similar to a water bottle for a hamster cage and will not overflow.
![Image]()
We’ll start at the farthest point from the MC (right rear wheel), working back to the closest (front left wheel). There’s no need to lift the truck, even a fat boy can fit. All of the bleeder valves will be facing towards the center of the truck. Pull the rubber cap, and using a 10mm wrench, break loose the valve (turning counterclockwise) and then close it loosely.
![Image]()
Insert the bleeder valve adapter (removed to drain the master cylinder) back into the drain hose and slip on the end of the valve.
![Image]()
With the air hooked up, pull and lock down the trigger to activate, then open the valve, ¾ to 1 full turn. When opened enough, you’ll see the hose start to jump/pulsate.
![Image]()
Once it starts to pump, crawl out and go ahead and sample your tasty beverage. The first and longest line will take the most time and drain the most fluid. When the collector reaches approximately ¾” deep, close the bleeder valve first, then release the trigger/pump action.
Remove the adapter from the valve, and using a white paper towel, hold under the valve and open it momentarily for a few drops of fluid, then close it. Inspect the oil stain on the white paper towel to insure you now have clean fluid at that point. If it’s clean, tighten the valve closed, replace the rubber cap, and move on to the left rear wheel. If it’s still dirty, hook up the adapter and repeat till clean.
Check the fluid level on your auto re-fill bottle, then move on to the left rear wheel and repeat to drain. This one will require a bit less fluid to run clean than the first one did.
![Image]()
When it’s running clean, move on to the front right wheel. Here, you can access the valve from the wheel well. It’s up top and facing rearward. When done, check your refill bottle’s fluid level and move on to finish at the front left wheel.
This fluid is 2 years old and has 22k miles on it….I was obviously overdue in flushing this.
![Image]()
Now, I have a nice firm pedal riding higher than before. No spongy feel and much less pressure needed to apply than before. I discovered a slight line blockage when draining the front right caliper, Now it’s flowing free.
One of the more important and most overlooked items of maintenance on our HDs, is the system’s Brake Fluid. Our brake system on the HD isn’t the best when new, so we need all the help we can get to extend the life.
Many people will drive their truck for years with the original fluid. Even when installing new linings, they’ll still ignore the fluid. Yet, in only 18-24 months, your brake fluid’s boiling point can drop as much as 200 degrees.
Today I flushed the system’s brake fluid, took some pics along the way, and wanted to share. You’ll need 2 quarts of fresh DOT-3 fluid.
There are many techniques used, and since I have an air compressor, I chose to use this kit from HF for $30.
Brake Fluid Bleeder
If you don’t have air, they have a manual pump for le$$. Either of these will be much better than having to yell at your Brother-in-law to mash the brake pedal.
Brake Bleeder & Brake Bleeder Vacuum Pump Kit
We’ll start at the Master Cylinder. Remove the bleeder valve adapter from the end of the suction line and insert to drain the old fluid.
Go ahead and dump the reservoir into your used/recycle oil container, readying the pump for the next step. This is what the old fluid looks like.
Fill the Master Cylinder with fresh fluid and ready the kit’s fill bottle. Here, we have a clean MC with fresh clear fluid, you can see to the bottom now.
Select the appropriate sized adapter for the auto refill bottle. The bottle has a ball valve to keep closed until in position and ready to start, and then open. This functions similar to a water bottle for a hamster cage and will not overflow.
We’ll start at the farthest point from the MC (right rear wheel), working back to the closest (front left wheel). There’s no need to lift the truck, even a fat boy can fit. All of the bleeder valves will be facing towards the center of the truck. Pull the rubber cap, and using a 10mm wrench, break loose the valve (turning counterclockwise) and then close it loosely.
Insert the bleeder valve adapter (removed to drain the master cylinder) back into the drain hose and slip on the end of the valve.
With the air hooked up, pull and lock down the trigger to activate, then open the valve, ¾ to 1 full turn. When opened enough, you’ll see the hose start to jump/pulsate.
Once it starts to pump, crawl out and go ahead and sample your tasty beverage. The first and longest line will take the most time and drain the most fluid. When the collector reaches approximately ¾” deep, close the bleeder valve first, then release the trigger/pump action.
Remove the adapter from the valve, and using a white paper towel, hold under the valve and open it momentarily for a few drops of fluid, then close it. Inspect the oil stain on the white paper towel to insure you now have clean fluid at that point. If it’s clean, tighten the valve closed, replace the rubber cap, and move on to the left rear wheel. If it’s still dirty, hook up the adapter and repeat till clean.
Check the fluid level on your auto re-fill bottle, then move on to the left rear wheel and repeat to drain. This one will require a bit less fluid to run clean than the first one did.
When it’s running clean, move on to the front right wheel. Here, you can access the valve from the wheel well. It’s up top and facing rearward. When done, check your refill bottle’s fluid level and move on to finish at the front left wheel.
This fluid is 2 years old and has 22k miles on it….I was obviously overdue in flushing this.
Now, I have a nice firm pedal riding higher than before. No spongy feel and much less pressure needed to apply than before. I discovered a slight line blockage when draining the front right caliper, Now it’s flowing free.
