Skip the auto shop - Our mechanics make house calls

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.

A: Hi there. From the description you have pro...

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 1000 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!

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: Rear window not going back up

Hi there. Most likely either the regulator or the window motor transmission is stripped. The faulty part will need to be replaced in either case. My advice would be to enlist the help of a mechanic, like one from YourMechanic,...

Q: Brake light comes on momentarily after hard braking (like going down a hill) but only after coming to a complete stop

If your brake fluid is a little low then when you brake hard or first stopping then the fluid my just need to be topped off. Have the fluid checked and if just a little low on fluid then top...

Q: Truck keeps bogs down and dies when I let off gas.

It is very possible that you have a weak fuel pump. Having to keep your foot on the accelerator to keep the engine running is an indication of low fuel pressure. The pump works harder at higher RPMs in order...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...