I’m going to show you how you can easily test the condition of brake fluid in your vehicle, in order to determine if you should keep the existing brake fluid or replace it. Now it’s important to note about brake fluid, non silicone types, is that it’s hygroscopic.

Hygroscopic means it wants to absorb moisture from the air. So, if you read the side of the brake fluid bottle , it’s going to say, make sure the cap is kept very tight. The purpose of that is to prevent moisture from being absorbed into the bottle.

How To Easily Test Brake Fluid [Best Brake Fluid Testers Review]Now, just by looking at break fluid, you’re not going to be able to tell the condition of the brake fluid. So, what we’re going to be testing for is the level of moisture in the brake fluid. It’s very important that the moisture content of the brake fluid is as low as possible.

The brake fluid is designed to have a very high boiling point. If the brake fluid has absorbed a fair amount of moisture from the air, what’s going to happen, the boiling point is going to become lower. That could become a big problem if you’re doing excessive braking and components in your brake system begin to heat up. You do not want the brake fluid to begin to boil. You also have the problem that moisture inside the brake fluid can lead to corrosion of brake components.

How to test brake fluid for water content?

PTE Brake Fluid Tester - calibrated for DOT 4 Brake fluids
  • Quick and easy way to test for moisture content in the brake fluid; results appear in seconds!
  • LED light indicators show percentage of water in the brake fluid
  • Calibrated for cars using DOT 4 brake fluid only (found in most cars produced since 2006)
  • Takes 1 x AAA/1.5V battery (included)
  • Only takes seconds to know the results

In order to perform the test, you’re going to require a brake fluid tester, the best is PTE Tester. You take it, insert it into the brake fluid, push the button on the end, and you’re going to have an indication of the water content in the brake fluid. So, if you look right at the tester, these two LED’s, which says okay, less than one percent, two percent.

If you see the LED’s on three percent or greater than four percent, you’re definitely going to wanna flush out that brake fluid from your system.
Brake fluid tester pens are rather inexpensive. They’re super compact, and you can put them right inside your tool pouch and have them ready to go.
Matt Seals, Auto Mechanic
Matt Seals
Phoenix Systems (3003-B) Brake Fluid Test Strips, 2 Strips Per Package, Reveals Brake Fluid Condition
  • May save you from paying for an un-needed brake fluid exchange.
  • Gives you the peace of mind that your brake fluid is good and is safely performing its proper function.
  • Identifies potential brake flulid related problems before they occur -thereby ensuring your safety.
  • Simply remove the test strip from the foil wrapper, dip it into your brake fluid and 60 seconds later you will know the condition of your brake fluid. (scientific proof)
  • Great for DOT 3, 4 and 5.1 brake fluid (most vehicles use DOT 3 or 4)

These simple-to-use strips are not moisture or petroleum tests, but the only MAP-approved copper test that identifies bad brake fluid in 60 seconds! These innovative BrakeStrip testing strips identify the exact level of copper ions in your brake fluid–an early sign of corrosion and extremely damaging to your brake system.

They’re easy to use; simply dip them in fluid, shake them off, and a minute later, match the test strip color with the included chart to see the level of copper in your brake fluid. BrakeStrip brake fluid test strips from Phoenix Systems are inexpensive safeguards to preserve your stopping power – aren’t you and your family worth it?

How To Easily Test Brake Fluid [Best Brake Fluid Testers Review]

How to Test Brake Fluid

How To Easily Test Brake Fluid [Best Brake Fluid Testers Review]I’m now going to give you a quick demonstration.

Right heres a sample of brand new brake fluid, lets take a look. Insert and as you can see it’s right around under one percent. Now you can also test using a digital multi meter. If you place it on a high ohms, ten mega ohm or higher resistance range. Place the tips about that far apart, and you’ll get a fairly accurate reading.

It won’t be as accurate as the pen or as quick but it will still give you and idea if the brake fluid has excessive levels of moisture or normal levels of moisture.

So, place it in, the reading you see should rise above five mega ohm if the fluid is acceptable. If it stays below five mega ohm, that’s an indication you’re going to want to change the brake fluid.

How To Easily Test Brake Fluid [Best Brake Fluid Testers Review]As you can see, it’s rising up and above the five mega ohm range. So, this brake fluid would be considered good.

Now lets take a reading on the vehicle to see how it compares to the brand new brake fluid, which gives us a reading of just under one percent.

Now I’m going to put the pen inside the brake fluid, only enough to submerge the majority of two probes. You can see the probes are about 3/16th of an inch apart. I could push the button first, you can see a green LED. I wanna make sure I do not see any red showing up. If I do, I’m going to have to flush the system. Here we go. As you can see, it’s not looking good. It’s showing the last one lighting up at four.

How To Easily Test Brake Fluid [Best Brake Fluid Testers Review]

Now that I know this brake fluid needs to be replaced, the next step you’re going to suction out the brake fluid from this reservoir. Once the reservoir is filled with fresh brake fluid, I’m going to begin the bleeding process with the furthest wheel from the cylinder, whish is going to be the passengers rear. Let me take off the rear wheel and show you how it’s done.

How To Easily Test Brake Fluid [Best Brake Fluid Testers Review]

Okay, the brake bleeding process is very simple. This is the Brake Fluid Check Valve Tool:

MonkeyJack Motorcycle Clutch Brake Bleeder Hose One Way Valve Tube Bleeding Tool Kit
This item is little bleeder - motorcycle brake bleeding kit.

In my case, it’s a ten millimeter open end wrench is going to loosen it to allow the brake fluid to escape. Now you don’t have to use a check valve like you see right here, but if you want one of these, it makes it very simple to bleed the brakes by yourself but if you don’t have a check valve, you can use a straight piece of vinyl tubing.

Make sure the end of the tubing is submerged inside brake fluid. Because what’s going to happen, as you push down on the brake pedal, the fluid is going to move forward and when you lift the pedal up it’s gonna wanna retract a little bit. So, you don’t wanna draw any air back into the system. That’s why you wanna keep the end of the tube, without a check valve, submerged in brake fluid.

So, what I’m going to do now is just loosen this, get in the car, continue to slowly push the pedal all the way down and up. Down and up until I see clear fluid flowing through the line without any air bubbles. While you’re doing this, make sure the reservoir is kept full. You do not want it to go dry and draw air into the system.

After pushing the pedal a few times, the line if full of liquid, there’s some air right here, check valve is holding everything from allowing air to go backwards. So, let me keep pressing and keep flushing out the old fluid. Once this is complete, you’re going to tighten the nut and remove this tool.

Also, keep the following points in mind as you check the brake system:

  • Brake fluid is toxic, so take any rags with more than just a couple of small spots of fluid on them and any partially used cans of fluid to a toxic waste center for disposal.

  • Don’t get brake fluid on anything that’s painted because brake fluid eats paint. If you spill any, wipe it up immediately and dispose of the rag ecologically!

  • Don’t get grease or oil in your brake fluid; either one may ruin your hydraulic brake system.