How do you check to see if your car has enough brake fluid? You’re going to need to open and inspect your car’s Master Cylinder. When you step on the brakes, fluid moves from this assembly into the brake lines. When you release the brakes, the fluid moves from the lines back into the master cylinder. This may sound intimidating, but it’s really very simple, as long as you follow a couple guidelines to keep everything clean and free of contaminates.
There are 2 kinds of fluid reservoirs that you may encounter when checking the brake fluid. The first type is a little plastic bottle on top of the master cylinder. To open this type, just open the cap.
The other type is the metal type, with a lid thats held in place by a metal bar or retaining clamp across the top. Just use a flat screwdriver and pry the clamp off the top. It should just flip to the side of the master cylinder.
Don’t let any dirt or junk fall into the chambers when take the lid off. If you see lots of dirt, grime, or dust around the master cylinder, wipe around the lid before you remove it.
If you have the removable lid, there are 2 diaphragm cups that move up and down as the fluid moves into and out of the cylinder. If your fluid level is low, or if the cups are in the lower position, push them back up with a clean finger before you put the lid back on.
The brake fluid should be up to the “full” line on the cylinder or within 1/2″ of the top of each chamber. If not, get the correct brake fluid for your vehicle and add some.
After you’re done inspecting and adding any fluid, close the lid as quickly as possible to avoid any oxygen or water vapor from the air contaminating the fluid.
Grab a flashlight and check under and around the master cylinder. If it’s been leaking, you’ll see evidence of it. Most master cylinders seal pretty well, so if you’re low on fluid you may have a leak somewhere else. It’s a good idea to check your master cylinder every couple months, especially if was low on fluid the last time you checked it.