brake master cylinder

medicpaul

Guest
Hi guys, I need to replace the brake master cylinder on my TDI, is this a difficult job?
 

Pyro

Guest
theres alot to do and alot to go wrong mate and with the breaks you dont want it to go wrong ;)i did mypunto took me about 6 hours with help from an exsperienced machaninc and i was in training but we did master replaced all the pipes under the hood and the slave cylider :)
 

Pyro

Guest
well if its that easy then go for it :cartman: my punto was a cu nt to do had a tiny engine but just couldnt get to it and taking all the pipes off was hard work did you drain the system??
 

medicpaul

Guest
Managed to get my hands on a haynes, sounds simple enough for the mk4 golf but no doubt the leon will be trouble, thats just sods law. According to mr haynes its a matter of undoing the pipes and removing the 2 mounting screws while installing is the same but blleding the brake system is required. Guess I'll need to look probaly tommorrow.
 

Steely

semiskimmed cupra R
Dec 30, 2008
1,425
5
Doncaster
the master cylinders the easy part, having to remove the brake servo from behind when thats failed is the hard part :p

two 12/13mm hex bolts hold it to the brake servo,

2 brake lines running from the bottom of the cylinder 11mm IIRC

no more than 2 hours to swap, the painful bit will be re bleeding them, Dont push your foot to the floor when pumping the pedal, This is what killed my brake servo buy splitting the internal diapragm,

this is on a 1.8t, and it meant disconnecting the engine from the car and dropping it 8-9 inches just to squease it out,

whats the issue with your brake master cylinder?

27022010238.jpg

27022010233.jpg

27022010236.jpg
 
Feb 28, 2010
1,367
1
Southampton
Steely, you seem to know what your talking about so can I ask you this:

During the summer now and again I noticed this hissing noise from the pedal area which then went as soon as I even brushed on the brake pedal. I do my share of track days, so uprated discs & it failed the MOT on the brake master cylinder start of the month. The reason was that a nipple was "leaking" and even though the car aced the brake efficiency test when sat idling you can put your foot all the way down on the brake pedal and it doesnt get harder. They fixed this but it didnt really feel any different and the wknd after I went around silverstone!
Now its all back to normal, hissing, full throw on the brake pedal etc! I dono what crappy fluid they put in and braided hoses are on my to do list.
Do you have any suggestions, what could it be? :( suggestions are servo and cylinder. I can get hold of a 2nd hand servo and mastercylinder - can these be serviced before going in?
Thanks for your help,
Andy
 

Steely

semiskimmed cupra R
Dec 30, 2008
1,425
5
Doncaster
Sorry for the late reply, only just reread this thread my bad :(

hissing contant whilst your foots on the brake pedal indicates split diaphragm in the servo if its inside the car, otherwise it could be a faulty vac line to the servo,

your master cylinder, i wouldnt think you'd have an issue with, everyone went on about how you can roll the seals on them, I went to the trouble of getting an old one from a scrappies and stripping it down, its near on impossible to roll them, you'll have to be very unlucky if you do,

the master cylinder has 2 chambers, with 2 bleed nipples, one controlling the front offside and rear nearside, and the other controlling the front near side and rear offside, ( same with any car)

you're best bleeding the master cylinder by pumping the pedal BUT only half way, do not put your foot to the floor***, do both nipples at the same time, with some aquatic air line on each one, each about a metre long, air bubbles in the master cylinder will cause soggy pedal :) (do this with the engine running to you'l clear it far quicker, just make sure the res is full)

hope this helps
 
Lecatona HPFP (High-pressure Fuel Pump Upgrades)