Low speed braking

[Secretasiansam]

Thanks. Maybe important to mention. Symptoms occurred after changing brake light bulbs. I uses a short 2x4 to depress the brake pedal while I checked bulbs. Did I blow a hole in the booster by pressing too hard with the car off?

[andrewwynn]

Originally Posted by Secretasiansam

I have these same symptoms. Vac pump pulls and pulses. I do hear a whoosh sound. Does this point to booster?
Thanks!

When do you hear the whoosh? Vac pump pulls air Ina lot of places. I have an internal vacuum leak in my valve cover causing fits.

[X5chemist]

whooshes sounds = bad brake booster
I did one not too long ago on a different vehicle. Hopefully it's not too hard on a X.

[andrewwynn]

You said "hard on". Bwahhaahhaa

[EODguy]

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[Mistermorgan]

I’ve replaced the booster, I didn’t swap the master cylinder (I actually bought one but got sent one for. LHD which was no good for me)

I’ve run through the bleeding procedure using my foxwell and I’ve gone from having a hard pedal to a completely soft pedal. Guessing the master cylinder needs to be replaced too


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[andrewwynn]

Two separate bleeding functions in foxwell. Did you do them both? Also did you use pressure @ reservoir or vacuum at the wheels? Vacuum method is said not to work.

[Mistermorgan]

I’m using NT510 and it only has one function, I was using vacuum at the wheels.

I’ll give it another go today with pressure at the res - would I be better off using INPA for the bleed function or does it not exist in there?

[80stech]

The best way to bleed brakes is with a second person on the pedal. Vacuum won't do it and pressure bleeders are a cheat for when you need to do it alone. You need to get enough flow to force air out of the high spots (like the front brake lines where they go into the hoses.) The scan tool procedure is only to get the last bit of air out that might be trapped in or in front of the ABS valve/pump. When changing the master cylinder it's a good idea to start bleeding there. Sometimes the last bit of air will slowly come out of the compensating port overnight.

[EODguy]

Don't forget that the e53 has you do each wheel is a certain order and going out of that order does seem to leave bubbles in the ABS block.

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