Possible servo problem
Turbo Mini Forums

Hi,

Just tried bleeding the brakes for the first time on my new mini and for some reason, the pedal goes 3/4's of the way then gets stiffer.

Then as you push through the stiff bit something gives and a noise around the brake servo makes a fast hissing noise like a massive air bubble has been pushed out! The servo jerks when this happens. As you let off a few little bubbles come back through to the servo resivour.

Im barely getting any fluid through the calipers too, all i can think off is that its some kind of air lock?

Not really sure, just wondered if anyone might know what the porblem is!!

Thanks,

Rich

its indeed air mate - keep bleedin them til it stops hissing - worked for me

Ant

Hi,
Try bleeding it at the master cylinder first.
When you've got fluid there, move to the wheels.
Cheers,
Gavin :)

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Is it direct servo or remote?

Thanks for the info! Ill try bleeding the servo later.

Im not sure what type servo it is ive only just got the car. how can you tell the difference then?

Cheers

Rich

direct is mounted on the pedal box and has physical linkages to it.

The remote's are mounted anywhere and is piped in.

Ahh ok thanks Iain, its direct then!

What where you thinking about then 1380turbo?

Im going to bled the servo now see what i come up with.

Rich

Took a quick video of what the servo is doing then the brake pedal is depressed.

http://s17.photobucket.com/albums/b85/Rich...nt=MOV00037.flv

Not really sure about how to bleed the master cylinder as theres no nipples or anything. How should it be done?

Rich

Hi,
Use the pipes like you would bleed nipples.
Crack pipe off 1/4 to 1/2 a turn, press pedal, tighten pipe, release pedal.
Repeat until fluid with no air comes out.
Cheers,
Gavin :)

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I run a remote servo rich 1275 and get the same thing under bleeding as the diaphragm in the servo moves. A slight hiss but the pedal is solid straight after.

Try what Bat suggests and let us know how you get on.

Karl

Hi, had a quick look at my brakes again today, tried further bleeding which seemed to help a little bit as the sound has now gone!

Carried on bleeding the wheels, then tested to see if when the pedal is depressed it would lock the front discs - no.

However when the brakes are pumped the pedal gets alot stiffer and the travel shortens, when you hold down the pedal after pumping the front discs are locked! Its as if there is air in the system and pumping compresses it, giving the desired effect on the calipers.

When the pedal is released after being held down (after pumping) there are several large bubbles that can be seen bubbling out of the corner of the resivour quite quickly, and lots of brown shit comes with them, filling up and settleing in the bottom of the resivour.

I can only think that there is air being trapped somewhere in the master cylinder, and its not being pushed out by bleeding the wheels.

Ive looked at the master cylinder on the servo but cannot see how to bleed it! If the pipes are taken off the side of the master cylinder the the rubber tube fitted over the pipe, surely this wouldnt have an effect, as the fluid comes out of the master cylinder then travels down the pipe? Obviusly if the pipe is taken out then the pedal pushed down then the fluid is just going to piss out the side of the master cylinder?

Can anyone help lol, im a tad confused:$

Rich

Yeah he meant undo the copper pipes coming out the side of the master cylinder and let the fluid piss out (while bleedin), then bleed as normal.

How do you mean "while bleeding"?

So i dont fully remove the pipes just endo them a few turns, depress the pedal then do them up and then release the pedal?

Is that right?

Rich

How do you mean "while bleeding"?

So i dont fully remove the pipes just endo them a few turns, depress the pedal then do them up and then release the pedal?

Is that right?

Rich

Go with this plan

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AAAAH i get it now. I thought you meant take the pipes completely out so i was getting confused!!

Ill have a go at bleeding the master cylinder later and see how it goes!

Rich

also try bleeding as good as you can, then if you can pump the brakes to get them to work, try pumping the pedal then holding it down hard with a block of wood against the seat. leave over night, remove the wood and try the brakes.

trust me this can and does work, also its so simple and quick its worth a try!