Here’s how to test your motorcycle brake fluid yourself, so you can tell if your motorcycle brake fluid has gone bad. We’ll also look at why motorcycle brake fluid goes bad to begin with, and what bad brake fluid can mean for you and your motorcycle.
Brake fluid is one of the two most fluids in your motorcycle, and most manufacturers recommend replacing your brake fluid every two years. However, in my experience looking at dozens of people’s motorcycles every week, I can tell you that a lot of people are neglecting their brake fluid.
Considering how important proper brake performance is to motorcycle riding, you should make sure you test your brake fluid to see if it has gone bad at least once every year. Luckily, there are three easy ways to do that. The three ways we’ll be testing our motorcycle brake fluid are by feel, by sight, or with a tester. First let’s talk about how brake fluid goes bad in the first place.
Why does brake fluid go bad?
Most motorcycles use either DOT 3, DOT 4, or DOT 5 brake fluid. In other words, most motorcycles use a brake fluid that is hygroscopic. Hygroscopic is an adjective that describes something that will absorb moisture from right out of the air into your brake lines. That means even if you don’t use your vehicle, the brake fluid inside of it will absorb water from the humidity in the air. Even 2% to 3% water in your braking system can make a serious impact on your braking performance.
Why is old brake fluid a problem?
Your hygroscopic brake fluid absorbs water over time, and water has a much higher boiling limit than brake fluid. That means pure brake fluid performs very well as your brakes heat up, but brake fluid with water in it performs poorly as your brakes get hot. Under heaving breaking, your braking system could overheat, leading to brake fade, which is when your braking system gets so hot that it stops working when you need it the most.
Another problem with moisture getting into your brake fluid, is that by introducing moisture into your braking system you can start to create rust internally which can lead to failures that you can’t see coming.
What is brake fade?
Brake fade is the result of components in your braking system overheating under heavy braking. Bad brake fluid might not lead to brake fade in city traffic speeds, but it could lead to brake fade at highway speeds. You’ll be coming to a stop as you apply your brakes, and suddenly you’ll start traveling more quickly again, as your brakes have stopped performing properly.
Testing motorcycle brake fluid
Obviously, brakes are critical to motorcycle riding, so we want them to work. There are three ways to test your motorcycle brake fluid: by sight, by feel, and using a small tester device. We’ll go over all three in detail.
Testing motorcycle brake fluid by sight
One symptom of brake fluid absorbing moisture is that brake fluid will go from looking like a very pale yellow color, to looking like whiskey (or darker). That’s why most motorcycle master cylinders (the reservoirs that hold your brake fluid) are either clear or semi-clear bottles, or they have a little sight glass, so you can look inside and see what color your brake fluid is.
You can tell whether or not your brake fluid has gone bad by looking at the color of the fluid. Is it light and clear, or does it look amber like a shot of whiskey, or even darker? Another way of knowing whether your motorcycle brake fluid is good or bad is by imagining you were giving a urine sample to a doctor: does the color look healthy, or does it look like you’re in dire need of some fresh fluids?
You can take a look at the video above to see a comparison of the color of new versus old brake fluid.
Testing motorcycle brake fluid by feel
Another symptom of your brake fluid having absorbed too much moisture is a spongy or squishy feel to your brake lever. When you squeeze your brake lever it should feel firm and crisp, not squishy. The right versus wrong feel for your brake lever should be like the difference between squeezing the glutes on an Olympic athlete versus squeezing granny fanny. Good brake fluid will make your lever feel firm and strong, bad brake fluid will feel flabby.
It’s difficult to describe the right and wrong feeling, but in the video above I go over showing you how the brake lever will react differently in a motorcycle with good brake fluid versus with bad brake fluid and the differences are easily seen on camera. Have a look if you’d like to learn more about testing motorcycle brake fluid by feel.
Testing motorcycle brake fluid by brake fluid tester
The last way to check your brake fluid is with an electronic brake fluid tester. You can pick these up for about $10 on Amazon. They read the moisture in your brake fluid and let you know if it’s time for replacement.
If you’re brand new to motorcycle maintenance and you aren’t confident in your experience you should consider buying a brake fluid tester to help you get started. To use it you simply put remove the brake fluid reservoir cap and diaphragm and stick the tester into your brake fluid. Lights on the side will indicate whether your brake fluid is GOOD (0% moisture), OK (1%-2% moisture, or BAD (3% moisture or more).
Be careful not to spill any DOT-4 brake fluid on your motorcycle while using the tester. DOT-4 brake fluid is highly corrosive and will damage the paint and finish of your motorcycle.
You can take a look at the video earlier in this article to see step by step instructions on how to use a brake fluid tester.
Final thoughts on how to check motorcycle brake fluid
For $10, a break fluid tester is a great tool for a first timer do-it-yourself’er who wants good peace of mind, however, it isn’t necessary. You can save yourself the money by just using the sight test (pee test) or the feel test (butt test).Of course, if it’s been more than two years, there’s no need to test your brake fluid, even if the motorcycle’s been sitting, it will still need fresh brake fluid.
However you decide to test your brake fluid, just make sure you do it. It’s a great practice whether it’s part of every day motorcycle maintenance, or part of restoring an old motorcycle.
If you found this content helpful, please consider subscribing to YouMotorcycle on YouTube and leaving a comment on the bottom of this page to let me know it helped you out. I always enjoy hearing from readers, it gives me the juice I need to keep making content to help motorcyclists. Thanks for your time in reading this. If you have any questions please let me know!
How do you change brake fluid?
You can change your motorcycle brake fluid yourself, a process called bleeding brakes, in these five steps:
- Remove the covers, lids, and diaphragms to access the master cylinder reservoirs
- Suck out old fluid with a siphon,syringe, or turkey baster
- Refill brake fluid reservoir with newDOT-4 brake fluid (verify your motorcycle uses DOT-4)
- Bleed the brakes (follow the process detailed here)
- Repeat the process on the other brake (front or rear)
You can also simply watch this video which will go over it:
Side note: A strobing brake light can help keep you safe
This cheap flashing LED brake light for motorcycles will keep you safe from rear end collisions on your next motorcycle ride!
Here is the short answer: Yes, brake fluid can go bad. Brake fluid absorbs moisture, which reduces its performance. For that reason, it's best practice to change brake fluid every two years. However, brake fluid is one of the maintenance items that drivers miss most often.Can you tell if brake fluid is bad? ›
Brake fluid is usually a light, clear color. If it's not clean or transparent, then your brake fluid is dirty and needs changing. The reservoir should have a label that says, “full line.” If the brake liquid falls below that line, it's a sign your need to change your brake fluid or top it off.How long does brake fluid last in a motorcycle? ›
Glycol-based brake fluid needs changing at regular intervals as recommended by Harley® for your bike. For most riders, that's every 1-2 years. If you use DOT 5 you can go longer between changes. You can tell it's time with a tester or by checking the color of what's currently in your system.What happens if you don't change brake fluid in motorcycle? ›
What happens if I don't replace my brake fluid? If you don't have your Brake Fluid changed as recommended by your vehicle manufacturer this will lead to moisture contamination in your brake reservoir where the Brake Fluid is stored. As your brake fluid ages, it's also bound to be contaminated with 'debris buildup'.What color should brake fluid be motorcycle? ›
Like we said above, fresh brake fluid should be almost clear with a hint of yellow coloring. If your brake fluid resembles oil, and is a dark brown or black color, then you need a brake fluid flush and replacement.What problems can old brake fluid cause? ›
What Happens to Brake Fluid over Time? Like oil, brake fluid loses its effectiveness over time. The fluid can absorb moisture, which can lead to corrosion in your hydraulics system and other problems that make your brakes less effective, decreasing your ability to stop in critical driving situations.What does bad brake fluid look like? ›
Old brake fluid tends to be muddy brown/black and looks like used motor oil. Like motor oil, brake fluid gets darker the more grime and debris it picks up. The dirtier it gets, the less effective it becomes. Dark brake fluid is a good sign you should consider a brake fluid flush.How do you know if your brake fluid is burnt out? ›
Strange Noises or Smells when Braking
Burning smells after hard braking could mean that you have burnt-out brake fluid. In this case, you should pull over your vehicle into a safe place and give it time to cool down. You should also contact a local mechanic for insight and schedule a service visit.
To check your brake fluid, remove the cover of the master cylinder and dip a strip into the fluid. Shake off the excess fluid and wait 60 seconds before comparing the color of the strip with the guide on the brake fluid tester package. The guide tells you when it's time to change the fluid.How often do you need to bleed motorcycle brake fluid? ›
Replacing your brake fluid and bleeding the system of air bubbles is regular maintenance that your owner's manual will likely suggest doing once every two years.
It's also a good idea to take the cap off the reservoir every month or two, simply to visually inspect the fluid. If it's still good, it will be glossy and semi-transparent. If it looks dirty in any way, it's a good idea to get your local mechanic or auto workshop to change the fluid for you.How often do you need to change brake fluid on a bike? ›
This can result in enough water being in the system that the boiling point of the brake fluid drops and the braking power begins to fade. To prevent this from happening, DOT fluid should be replaced every 6 months.Can you just change brake fluid without bleeding? ›
A simple method to accomplish this without bleeding is to suck most of the fluid out of the master cylinder with a pump or kitchen meat basting utensil. Make sure you don't expose the circuit to air when taking the fluid out. Then refill with fresh fluid.What happens if I dont flush brake fluid? ›
Corrosion and rust can cause structural damage to your braking system, leading to costly repairs. Regular brake fluid service can prevent these deeper system issues from occurring. Brake fluid flushes are recommended every 30,000 miles or 2 years, depending on your driving and braking patterns.What color is bad brake fluid? ›
Fresh brake fluid should be relatively clear, if not slightly golden. This is true for practically any type of brake fluid. Over time, brake fluid becomes contaminated. When the brake fluid begins to darken and turn black or brown, then you know that the fluid is becoming too old.How important is it to change brake fluid motorcycle? ›
Changing your motorbike's brake fluid is a relatively easy DIY job. It may be hidden from view, but the liquid inside your bike's braking system should never be taken for granted. Over time the fluid degrades and overall performance can be affected, so regular changes are vital.Does brand of brake fluid matter motorcycle? ›
It is crucial you use the fluid specified by your brake manufacturer. Failure to do so will result in premature brake failure.Why is my motorcycle back brake squeaking? ›
If your pads still have enough material on them, the squeaking is most likely caused by debris getting trapped between the brake pad surface and the rotor surface, or by contamination of either the pad or rotor. This can happen while riding, obviously, as dirt, oil or debris can get kicked up from the road or trail.Can brake fluid last 10 years? ›
Brake fluid lives in a sealed system and can survive for years, but moisture from the surrounding air can work its way in through hoses and other parts of the brake system.Can old brake fluid make brakes soft? ›
Then it could be that old brake fluid is causing the poor brake performance. Or, you could have a possible leak causing your fluid to be low. Either way, get it checked out! This is one of the most common causes of spongy brakes.
Brake fluid does go bad. Your brake fluid is held inside a sealed system, and most of the time, it will last you at least a couple of years. However, moisture in the surrounding air can seep into the lines and other brake system parts, or components can wear out and cause a fluid leak.Why does brake fluid go black? ›
Normal Aging Gone to the Extreme: The most common reason that brake fluid appears brown or black is that normal ageing has gone unchecked (you haven't had the fluid changed in too long). Contaminants collect in the fluid, darkening the colour and reducing its ability to work.What does brake fluid smell like when it burns? ›
It smells like fish oil. You can find this leak in the middle or rear wheels. Brake fluids are slippery than engine oil. If brake fluid is leaking, have the vehicle repaired right away.What does dried brake fluid look like? ›
It's typically light yellow in color, but will brown as it ages. Now that you know what color brake fluid is, if you see it under your car around your wheel wells, you have a leak.Do you pump brakes after adding brake fluid? ›
Do You Have To Pump The Brakes After Adding Fluid. YES. You HAVE TO pump the brakes to push the fluid back through the system when you have finished.Do I check my brake fluid hot or cold? ›
It is best to check when the car is cold as the measurement provided is not only safer but also more accurate as liquid of any kind expands when heated. You should not check the brake fluid when the car is hot, as you will likely burn yourself.What tool do you use to test brake fluid? ›
Using a boiling point tester is the only accurate way to test brake fluid performance. It takes less than a minute to measure the boiling point and confirm if the brake fluid has absorbed too much moisture to be safe.How do I know if my bike brakes need bleeding? ›
Some telltale signs that the brakes on your bike need to be bled are that they feel squishy, or that you have to pull the lever almost all the way to the handlebars before they work. Bleeding your brakes will return braking power and precision.Do you bleed motorcycle brakes with cap on or off? ›
Pop the reservoir cap off if you haven't already, then slowly pump the brake lever – you might see some air bubbles appear; keep pumping until you don't see any more to complete bleeding of the master cylinder. You can now loosely refit the reservoir cap.Is it easy to bleed motorcycle brakes? ›
Chances are if you ride dirt bikes, ATVs, or operate any other wheeled powersports machine, you will eventually have to bleed your brakes. Brake bleeding in itself is not a difficult job, but there are a handful of tips and tricks that can make the process go more smoothly and result in better performing brakes.
For most motorbike use, it is only DOT 4 and DOT 5.1 that you need to concern yourself with, and it is likely that it will be one of these fluids that is recommended for your motorcycle. As DOT 5.1 is more hygroscopic than DOT 4 and therefore absorbs more moisture, it will need to be changed more often.What is the difference between DOT 3 and DOT 4 brake fluid for motorcycle? ›
The difference between DOT 3 and 4 is the boiling point—DOT 4's higher rating means it doesn't boil as quickly. DOT 5 fluids have ratings too, but they're silicone-based and don't absorb water like DOT 3 or 4.Can I use DOT 4 brake fluid in a Harley? ›
However, most Harley-Davidson® motorcycles use DOT 4 as DOT 5 compressibility and viscosity are not suitable for ABS. Remember to use always the recommended grade for your motorbike or higher.How do you check brake fluid on a bike? ›
HOW TO CHECK: Brake fluid reservoirs are usually found on the handlebars for the front brakes and near the rear tyre for the rear. Both of them have small glass windows marked with MAX and MIN level. The level of oil should be in between the MAX and MIN mark.How much does a brake fluid flush cost? ›
The costs of changing the brake fluid, or doing a brake fluid flush, should cost between $80 to $130 and should be done by a professional mechanic to ensure safety. These costs can vary based on whether you want to change the fluid yourself and the type of fluid you have.How long before brake fluid goes bad? ›
YOU SHOULD REPLACE BRAKE FLUID EVERY FEW YEARS
And the best way to find out how often to change brake fluid is to follow your manufacturer's recommendations. Some manufacturers say you should replace your brake fluid every two years. Others recommend every three years, or every 45,000 miles.
A short answer to this question is yes. Motor oil can only last for a certain period of time. That's why it comes with an expiry date. For this reason, oil goes bad with time just by sitting in the engine.When should I change my bike brake fluid? ›
But generally, the brake fluid level should be checked every month or so, and topped up if needed and it should be completely changed every two years. Before you start: There are different types of brake fluid used in motorcycles.What color should brake fluid be? ›
So, what does brake fluid look like? It's typically light yellow in color, but will brown as it ages. Now that you know what color brake fluid is, if you see it under your car around your wheel wells, you have a leak.Can you change brake fluid without bleeding? ›
A simple method to accomplish this without bleeding is to suck most of the fluid out of the master cylinder with a pump or kitchen meat basting utensil. Make sure you don't expose the circuit to air when taking the fluid out. Then refill with fresh fluid.
Brake fluid plays a vital role in your braking system, yet it's often ignored or forgotten. What happens if you run out of brake fluid? You risk your brakes failing completely, which is a huge safety concern. However, it is possible to stop safely when your brakes fail.How long can a motorcycle sit before it goes bad? ›
If you've never prepared your motorcycle for storage, we have a helpful guide on how to store a motorcycle on our website. When properly prepared and stored, a motorcycle can sit for up to 24 months without being ridden.Does sitting idle burn oil? ›
Car idling burns oil. The longer you leave your engine running means the more oil that has to circulate and burn. That means more frequent oil changes. It's bad for the environment.Does changing brake fluid improve braking? ›
Changing the brake fluid will improve braking providing there are no underlying issues with your braking system. Aging brake fluid will become contaminated with water and metal particles from the parts that make up the braking system, changing the fluid will prevent corrosion and the components eventually failing.What does dirty brake fluid look like? ›
Old brake fluid tends to be muddy brown/black and looks like used motor oil. Like motor oil, brake fluid gets darker the more grime and debris it picks up. The dirtier it gets, the less effective it becomes. Dark brake fluid is a good sign you should consider a brake fluid flush.How much does a motorcycle brake flush cost? ›
The costs of changing the brake fluid, or doing a brake fluid flush, should cost between $80 to $130 and should be done by a professional mechanic to ensure safety. These costs can vary based on whether you want to change the fluid yourself and the type of fluid you have.