Q: Brakes not pumping up.

asked by on

Brakes will not bleed or even pump up. Brake fluid is not going into the master cylinder. Already installed new master cylinder and made sure the booster was working to push the cylinder in.

My car has 104000 miles.
My car has an automatic transmission.

The best thing to do with a new master cylinder is to bench bleed it. Here’s how:

  1. You use a vice to grab the nubs of the master cylinder and mount it up about waist high. If you don’t have a vice, there is usually another way to hold the master cylinder.

  2. Most master cylinders come with a couple of hoses and some threaded fittings. You attach the fitting to where the brake lines go, attach the hoses to the fitting and place the ends of the hoses into the master cylinder reservoir.

  3. Use a large Phillips head screwdriver to push the piston of the master cylinder in. Be careful not to push it in to the end of its travel. It could damage the inner seals and you don’t have to use a Phillips head screwdriver, just something like it.

  4. Keep pushing it in and out until the lines you have placed in the reservoir are no longer pushing air into the reservoir.

  5. Keep the lines in the reservoir and mount the master cylinder to the car.

  6. Remove the bleeder lines and attach the brake lines.

  7. Begin at the right rear wheel and bleed all four wheels until you don’t see any air coming out. Remember you will need to move the the air bubble from the master cylinder to the wheel you are bleeding at. This means to keep in mind how much fluid that is that will need to be moved through the line.

It is often hard to get fluid moving through a master cylinder on the car. If you don’t want to remove the master cylinder from the car, remove the brake lines and follow the bleeding procedure as if the master cylinder were mounted in a vise. Sometimes you have to use slow short strokes to get the bleeding started.

If you should need assistance with this, I recommend enlisting a certified technician, such as one from YourMechanic who can flush the brake system at your own convenience.

Good luck!

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Brakes not pumping up.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car started shaking won't start engine light keeps flashing

Hi There, Generally, the check engine light comes on when something fairly serious is going on with the vehicle. This can happen for many different reasons such as a faulty mass air flow sensor, a faulty O2 sensor, a bad...

Q: Whining from transmission to rear end area 2007 Chevrolet Silverado 1500

Hello - your intuition is correct. The ring and pinion gear are severely worn, and will need to be replaced (w/all new ring and pinion bearings) to eliminate the "noise under load" you notice. Setting up a ring & pinion...

Q: Possible braking issue.

Your vehicle is new enough that there should be a manufacturer warranty so do avail yourself of that protection. If you believe the brakes have actuated, or are sticking, in one of these episodes, simply pull over and measure (or...

Related articles

What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.