Q: Cannot flush the brake system

asked by on

I have a 1985 Ford Mustang, 2.3l with only 29,000 miles. I am trying to flush the brake lines.

I have a small vacuum pump as can be found in any auto store. With great effort I was able to flush the right rear (drum) brake. However, although all the other bleeders are free, I cannot get any brake fluid out of the other three wheels (front disc) although the pump shows about 15" of vacuum. The pedal is firm, with no signs of air in the system, nor does the car pull to either side.

I removed the bleeder on the left rear wheel and it is not clogged.

For what it's worth, I drove the car after filling the master cylinder with new fluid and flushing the right rear. Now the front brakes (large) reservoir shows some old fluid, but the small rear brake reservoir still appears clear to me. I don't know if that means something is amiss with the rear brakes, but in any event that wouldn't explain why I can't flush the front brakes.

I'd appreciate any advice you can offer.

My car has 29000 miles.
My car has an automatic transmission.

Hi there. From the description you have provided for flushing your vehicle’s brake fluid, something is amiss. Assuming, your vehicle is not equipped with ABS (anti-lock braking system) it could be a problem with combination/proportioning valve not allowing fluid to flow, with a vacuum pump.

It could also be the master cylinder not allowing the fluid to flow. Considering your vehicle has a good, firm brake pedal and no pulling issues. I would not recommend replacing either component.

You could try flushing the system with an assistant. Open the bleeder, have an assistant depress the brake pedal and hold while you tighten the bleeder. Have your assistant release the brake pedal and then repeat the procedure until fresh fluid is seen. A clear vacuum tube would help direct the dirty fluid into a container. If you would like to have this done, a qualified professional from YourMechanic can perform this brake fluid service at your home or office.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. Cannot flush the brake system

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 making squealing noise like some things being sheared off. 1991 Ford Mustang

Hello - setting up the ring and pinion gears in the differential is a highly specialized task, requiring specialized knowledge and tools. And the parts are not inexpensive, so all the more important to get this right up front. Check...

Q: Clunking car when I go over bumps

Basically, any bolted on or "jointed" moving part or bushing could account for noise in the front end. Not included in your list are rack and pinion mounts/bushings, strut bearings, tie rod ends, even brake parts (caliper torque plate), loose...

Q: Changed transmission and now have NO indication what gear i am using, is this legal?

As for the legality of this particular setup on your vehicle, I would recommend Consulting with local or state professionals who can guide you in the right direction as to what particular modifications are not allowed in your state on...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...