For some reason I always seem to get air in my brake system when I change my brake pads! On more than one occasion I have changed the pads only to get the "spongy" brake pedal. I purchased one of those MittyVac One-man brake bleeders but have not had success getting the air out of the system.

1) Is there a trick to changing the pads and not getting air in the system and

2) If I do get air in the system, is there a trick to using the bleeder?

 

First off, there is no way to get air into the calipers unless your opening the bleeder and letting it in. It's a completely closed system except for the Reservoir. I generally do not open the bleeders to get the pistons to retract. I manually compress them back into the cylinders after extracting fluid from the reservoir (otherwise the returning fluids will overfill the reservoir and then you have brake fluid dripping on your car.

YouTube has several good vids. on bleading brakes.
This one is accurate.

Couple things to keep in mind... First and foremost, is that brake fluid eats paint. Always have clean rags at the ready and use caution.
Also the vid excludes a common practice.... Always begin with the brake that is furthest from the reservoir, then bleeding the next furthest and so on and so on...
When bleeding the system, never let the reservoir go dry, or it will suck air into the system, and you have to start all over again.

 

What Vince is saying above is all good. I too want to add that you should not be picking up air from pad replacement.

I do the same as Vince, I draw fluid out of my reservoir before pushing the pistons back into the calipers, followed by a replacement of the brake fluid by simple, "wife pushing the brake" method. In my last two Jags, changing the fluid following pad changes was a matter of a few minutes, no air bubbles what so ever.

I had only one car that did what you are describing, it was a Lamborghini. It seem to have generated its own air supply in the brake lines; my wife could attest to the hours we had spent trying to evacuate the air from the system. Finally, what fixed it was changing out the power brake vacuum unit. Somehow, and I do not know how, it introduced the air bubbles into the system.

Make sure that your method of pumping does not cause cavitation, which would be the source of the air bubbles. All pumping should be done slowly and smoothly, rather than hurriedly and abruptly. There is also a chance you have a piston seal that is sucking air as the pistons are pushed alternately back into the caliper. Well, these are guesses but, something is not right in your system.

Good luck troubleshooting,

Albert

 

Thanks guys! You each brought up things that I have been doing incorrectly:
1) @CleverName-I always open the bleeder screw and then retract the piston
2) @axr6-I have been pumping rather quickly

I also always encounter difficulty retracting the rear calipers. I typically remove the calipers and use a vise grip to rotate the piston. I bought one of those kits that include interchangeable disks but none of the disk fit my pistons. The drivers side goes in real easy but the passenger side take some elbow grease.

I took the car into the dealer and they bled the system and replaced the fluid. However I am now getting a fault message that says "Can not apply park brake".

 

@CleveName-I noticed that in the video the tech opens the bleeder screw and then pumps 15 times. I was under the impression that you are supposed to pump 15 times and then open the bleeder screw. Which method is ideal?

 

There is no real "count" so to speak, I always watching for clean fluid,that is the key your working for.... Not sure I grasp your whole question...Putting a vacuum on a bleeder that is not open accomplishes nothing.

As for your parking brake, I would guess they forgot to calibrate it after working on your car...

My data is for an 07-09 and references a special switch used to activate and deactivate the parking system from the fuse block behind the rear seat.
Personally, I would give it a try using the primary switch because you have nothing to loose... Otherwise its back to the dealer ya go..
Here is the procedure from my manual:

Parking Brake Calibration
The parking brake system must be calibrated whenever the battery has been disconnected or has been in a state of discharge, or repairs have been carried out to the rear service or parking brake system.
NOTE:
If new rear brake pads have been installed, pressure must be applied to the brake pedal a minimum of five times prior to calibration of the parking brake system.

To calibrate the parking brake system:
1 . Place gear selector lever in 'P' Park position.
2 . Release parking brake cable tension to service position. Parking Brake Cable Tension Release
3 . Set the ignition status to 'ON'.
4 . Apply and hold the footbrake then pull up the parking brake switch.
5 . To release the parking brake, apply and hold the footbrake then release and press down the parking brake switch.

Without the special tool/switch... I read this as
1. ignition off, in park.
2. ignition to "On" (not start)
3. press and hold foot brake while setting parking brake to "on" (pull up)
4. Press and hold foot brake while setting parking brake to "off" (press down)

Hope it works for ya!...

BOL
Vince

 

Add one "note to self" in your bleed procedure. Do not open the bleed nipple too far as your vacuum will draw air around the threads of the nipple as opposed to fluid from the caliper.

I learned this the way I learn most things --- the hard way.