E53 Brake Booster Removal

[sam512bb]

Good day All,

I thought I would post up my experience with replacing the brake booster on my 2004 X5 4.4L... As found on various sites on the internet, my X5 exhibited the same symptoms of a brake booster failure... one needed to use a lot of pedal pressure to brake. Having researched the issue I found a few threads on other sites that detailed the removal of the brake booster. These threads were quite helpful, but all required the disconnection of the master cylinder. Doing this will require bleeding of the entire system and to do so requires a specialty diagnostic tool (via OBD) for the process. I tried to find any threads where the master cylinder could be left in place, but found none. In fact the booster removal thread posters thought it unlikely that one could remove the booster without removing the master cylinder (MC)... Well, I can tell you absolutely that you can remove and reinstall the brake booster without removing the master cylinder, as I just did it myself earlier today. The entire process took about 3-4 hours with a few breaks (if you can forgive the pun) as I worked.

There is a lot of info on what to remove to get to the booster and MC and so there is no point for me to reiterate. The only real trick is to:

a. Unbolt the MC from the booster and leave in place
b. Ensure that all plastic brackets, etc that hold the brake lines in place are disconnected and free to move
c. Go into the cabin and disconnect the booster from the firewall and dislodge the clip holding the pin and brake pedal

Now that this assembly is free you can pull the booster forward along with the MC. Once the booster is loose you can wiggle the MC and carefully push it away from the Booster. Be careful not to bend the brake lines too much. Once the MC is clear of the booster, you can remove the booster. In my case the booster came out if I angled it towards the engine. That was it...

I used a Cardone replacement booster and it came with its own MC to Booster seal. This seal is not the same as the original OEM one and is slightly larger in its outer diameter. Consequently, I left the original seal and used the Cardone seal as well. This allows the original to seal between the inner hole the MC and the cardone between the MC surface and the booster surface. I then loosely installed the booster and positioned it so it was oriented correctly, but askew in the fire wall. I made sure the brake pedal rod was in a suitable position for attachment. I then mounted the MC to the booster and started the mounting nuts and ensuring that the MC and booster were mating properly. Tightening slowly on either nut to ensure all was fine. I was careful not to overtighten these nuts.

I then pushed the booster in place while ensuring the pedal rod was correctly oriented. Once this was done I installed the mounting nuts on the inside of the firewall and again alternating tightening each side and double checking that the booster was fitting correctly. Once in place I tightened it all up including the brake line connections that I loosened and put everything back together. The only issue was to push the brake lines back into the holders, rubbers, etc ... and leaving the MC in place did bend the brake lines a bit. However, this was not a big issue and everything went back together fine. More importantly, everything is working great and I did not have to rebleed my brake system which save a lot of time.

I hope the above helps anyone who is thinking about doing this job.

Cheers.

[Romocarguy]

Sam512bb. VERY helpful post. Same issue w my 06’ 4.4 and as I was contemplating a DIY I was concerned about whether or not I had to remove MC. You’ve given me the confidence to forge ahead. One question, did you find it necessary to remove wiper linkage arms that are attached to wiper motor? Thanks.