Brake
bleeding is a repair job that must be done throughout the life span of a car. Parts
avatar advises to bleed your car’s brakes every two or three years.
Whenever our mechanic
advises to bleed the car’s brakes, we often ignore it. It is not like we are
waiting for our car to break down. So why not give it a go now rather waiting
for the damage to occur. Most automobile manufacturers advise to bleed your
vehicle’s brakes every three years. As the fluid’s heat resistance reduces by
time, it can cause brake system to corrode. So it is necessary to bleed the
brakes to get optimum performance out of brake system.
Before moving further, let’s
know what is bleeding of brakes and why it is necessary.
Basically, when we are
bleeding the brakes, we are actually removing air out of hydraulic brake lines of car. Air makes its way
through leaks in brake system components. Brake fluid’s heating resistance
decreases by time as over the period of time it absorbs water from atmosphere.
Due to friction, caused by heavy braking, fluid heats up thus turning water
into steam. Air leaking in the brake lines makes the pedal spongy, and in worst
cases the brakes may fail completely.
Before starting
bleeding process, it is essential to check the brake system parts for leakage.
If you find a leak, replace the faulty component immediately. Entire braking
system is like a closed compound so if the fluid level is low, that means there
may be a leak in master cylinder. So fix the leak first. Front and rear Brake pads of car wear out frequently so
they may also cause air to enter the brake system. Brake pads should also be
replaced if necessary.
PRE - BRAKE BLEEDING
PREPARATIONS
Have all the tools
prepared beforehand. For the full replacement of the fluid in the brake system
you will need at least three cans of brake fluid. 10mm box wrench for disc
brakes and 8mm box wrench for drum brakes can be used if necessary. You will
also need one way bleeder screws, pressure brake bleeder and vacuum brake
bleeder to bleed the brakes. No matter what method for bleeding you use, same
tools are used.
Before you plan to
bleed the brakes, loosen the bleeder valves by applying the penetrating oil.
When you place the vehicle on the jack stands, on the day of bleed, after
removing all four wheels, tighten one lug nut against rear and front disc brake rotor of car's brake system and place a
square object to keep the brake pedal from falling to the floor when you start
bleeding. Mostly you have to bleed the brakes several times, so keep the
equipments ready with you.
If you see the traces of air in the system, bleed it
again until there is no air and fluid is flowing clearly inside. Also the fluid
to be used for bleeding should be manufacturer’s recommended. There are DOT
ratings specified by the manufacturer. Not every vehicle runs on same brake fluid of car
so check owner’s manual before buying any fluid.
THE BLEEDING TASK
In bleeding task you
can either do it yourself or can take help of your friend.
Step
1
Jack up the car and secure with jack
stands. Now remove all the four wheels.
Step
2
The next task is to
locate the bleeder screw and spray them with penetrating oil. Find the proper
wrench that fits the screw and loosen the screw. Using proper wrench could
decrease chances of screw’s hex head going round. If the screw is stuck, you
can spray penetrator like WD- 40. After doing so, retighten all the screws
again.
Step
3
Now, the fluid level in
the master cylinder should be checked. If the fluid level is lower, then add
more fluid level up to the mark. This process should be done at frequent levels
because its level drops as the old fluid is drained off. Filling it to the top
is necessary because if the reservoir empties, air will get into the system and
you will have to repeat the whole task to release the air out. Always use
manufacturer’s recommended fluid. Using any other fluid may damage the brake
system as not every fluid is compatible with every brake system. Do not spill
the fluid because it penetrates easily.
Step
4
You must keep owners
manual with you. The sequence of bleeding the brakes differs from one car to
other. This information can be found in owner’s manual. In some cars, the most
distant brake from the master cylinder of car is bled first. For
example, if you ware bleeding a rear wheel drive vehicle then start with right
rear wheel, then move to the left rear wheel; then move it to the right front
wheel and eventually to left front wheel.
Step
5
After bleeding each
brake properly and adding fluid to the master cylinder, pump the brake several
times when the car’s engine is off with the help of a helper. Brake pedal
should no longer feel spongy when you press it. If there is still spongy
feeling coming while pressing the brake, master cylinder and bleeder screws
must be checked again.
Step
6
When your helper
maintains pressure on the pedal, open the bleeder screw a small amount. The
fluid will pass through the clear tube and the pedal will begin dropping
towards the floor. When your helper signals you for “floor”, close the bleeder
screw. Also check the fluid level again.
Repeat the process of
pumping the brake, opening the bleeder screw and closing it, several times
until the stream of fluid flowing is free of air bubbles. After every five
times the brake pedal is depressed, top off the master cylinder reservoir with
fresh fluid. Do not let the air enter the master cylinder in any case.
Repeat these steps on
the remaining three brake locations in the sequence instructed in your owner’s
manual. If there is fluid eruption, there may be some air bubbles still trapped
in the system.
Step
7
Visually inspect all
the bleeder screws for any signs of leakage. Check that all the bleeder screws
are tight. Put the tires back on. Test the brakes before heading out onto the
road.
To test the brakes on
the road, wait until there is no traffic, drive slowly and press brake pedal as
you would normally. The car should pull up quickly and the pedal should not
feel spongy.
Now your brakes have
been properly bled.
There are several ways
to bleed the brakes like pump and hold method, vacuum method and pressure
method. So you can choose whatever method you want to provided you successfully
the air out of the brake system. You can consult your owner’s manual if you
find difficulty in locating the components of brake system.
For other brake
system part’s aftermarket purchase, do not forget to visit Partsavatar.ca
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