I want to check the brake fluid level of my car, its my first time so I dont know how to check it.

  • Recommend you purchase a Chilton or Haynes repair manual for your car. It tells you how to do that and a whole lot more. $20 well spent.
    – zipzit
    Aug 2, 2017 at 10:04
  • @zipzit - Agree with you, but will tell you these manuals are now running ~$35/ea ... ask me how I know, lol. Aug 3, 2017 at 12:59

1 Answer 1


To check the brake fluid in your master cylinder, follow these steps:

1. Open the brake fluid reservoir on top of your master cylinder of your car: If you have the kind with a little plastic bottle on top, just unscrew the cap on the little plastic bottle that sits on top of the master cylinder of car. If you have a metal reservoir, use a screwdriver to pry the retaining clamp off the top.

WARNING: Don’t let any dirt fall into the chambers when you open the lid. If your hood area is full of grime and dust, wipe the lid before you remove it.

2. Take a look at the lid: As the brake fluid in your master cylinder recedes (when it’s forced into the brake lines), the diaphragm cups are pushed down by air that comes in through vents in the lid. The cups descend and touch the surface of the remaining brake fluid to prevent evaporation and to keep the dust and dirt out. When the fluid flows back in, the cups are pushed back up.

3. Look inside the master cylinder of the car: The brake fluid should be up to the “Full” line on the side of the cylinder or within 1⁄2 inch of the top of each chamber. If it isn’t, buy the proper brake fluid for your vehicle and add it until the level meets the line.

NOTE: Close the brake fluid reservoir as quickly as possible so that oxygen or water vapour in the air doesn’t contaminate the fluid. And try not to drip it on anything; it eats paint!

  1. If both chambers of your car’s master cylinder are filled with brake fluid to the proper level, close the master cylinder carefully, without letting any dirt falls into it.

Because most master cylinders are pretty airtight, you shouldn’t lose brake fluid in any quantity unless it’s leaking out somewhere else.

5. Use a flashlight to look for stain marks, wetness or gunk under the master cylinder:

If your car’s master cylinder is or has been leaking, you’ll see evidence of it when you look closely.

  • Addendum: brake fluid is corrosive, so if you accidentally drop it on painted parts, remember to wash with water immediately! If you don't have water immediately available, don't use windshield washer fluid as a substitute as the components in the engine bay may not withstand washer fluid. I accidentally dropped brake fluid on the brake booster, then washed with windshield washer fluid (thought it was a good idea to do that), then the booster become so full of rust I had to sand and re-paint it.
    – juhist
    Aug 2, 2017 at 11:32
  • The brake fluid should only be to the "Full" line on the reservoir when your brake pads are new. As your brake pads wear, the level will go down slightly. As long as it is above the minimum mark you are ok. If you top off your fluid when your pads are worn, then the fluid can spill out over the top when you replace your pads.
    – Glen Yates
    Aug 2, 2017 at 15:39

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