How to fix spongy brakes, or carry out a brake fluid bleed
This is a bleeding process which i have used for over 10 years on everything from motorbikes, cars, trucks and rally cars.
It is as follows : ------
Use 2 people....i know this may be hard to arrange but i have even used my mom.
Use one person to sit in the vehicle, engine off. Now firstly go to the furthest brake bleed nipple from the reservoir. If the reservoir is located on the left hand front of the vehicle, then go to the right hand rear nipple (with wheels off, preferably). And vice-versa.
Next, with the nipple CLOSED, get the assistant to pump the brakes slowly (do not go fast, it is not a race....lol). Down, as far as it will go, and all the way up....repeat 2-3 times.
Next, get them to hold the brake pedal down, now OPEN the bleed nipple, and ask them to repeat, all the way down, and then up again, 2- 3 times, then CLOSE the nipple. This flushes the system out. Again, sloooowly.
Next, with the NIPPLE closed, get assistant to pump the pedal again SLOWLY 2-3 times, this action forces the remaining air in the system to the nipple end of the brake lines.
Next, have your assistant hold the pedal down, gently OPEN the nipple slowly until the fluid comes out...as the fluid is still coming, CLOSE the bleed nipple. DO NOT let them get to the bottom of the stroke.
What happenes if they reach the floor, and you still have the nipple OPEN, is that a small amount of air leaks into the system, and after a couple of days driving with heat expansion, your brakes are spongy again.
Repeat this 2-3 times on that wheel.
Go to the opposite side of the vehilce now, the left hand rear wheel and perform the same action.
Then the right front wheel.
And finally the left front wheel, the closest to the brake master cylinder reservoir.
Remember to use fresh, new up to date brake fluid.
And use a clear tube or straight into a bucket, so that you can see successfully the air coming out of the system.
Failing this, if you have bled the sytem properly, and this still occurs, and you have no leaks, it is time for a brake master cylinder replacement.
As there is a number of rubber seals that keep each brake sytem seperate, within the master cylinder as a safety precaution. If one sytem fails...ie left front brake hose leaks, then that side of the sytem (the left front and right rear, in a opposite system) will leak out, BUT the right front system(which includes the left rear as well)will still maintain pressure to be able to slow the vehicle down to a stop (obviously with increased pedal travel)
REMEMBER not to get any brake fluid on the paintwork, as it is a great paint remover (over time). If you do get it on the paintwork, just wash off with water immediately.
I hope this helps all of those who read this advice.
Please vote if you liked it !!!
And happy motoring.............
on Jun 30, 2010 | Mitsubishi Outlander Cars & Trucks