How The **** Do You Change The Brake Master Cylinder In Mk4 Gti?

[morepatrols]

Hi all,
 
The usual braking problem has been found in my 2000 Mk4 Vw Golf GTi 150 ps AUM.
 
Going to change the brake master cylinder due to the very soft and foot to be floor feeling with little braking effect.
 
Understand the ABS will need bleeding via a VAG link and VCDS.
 
The hard questions are as follows:
 
1 - Does VCDS lite allow the ABS to be bled?
2 - How do you remove the master cylinder:
2a - Access to offside mounting bolt is impossible
2b - Access to the brake lines is virtually impossible
 
I guess i remove the reservoir from the master cylinder (again access to the plastic lock catch is impossible), then this gives me access to the bolts.
 
Brake lines I just cant see how I can get access to them.
 
Any thoughts, suggestions, pictures, videos, tips etc will be well welcomed!
 
Cheers
 
Paul

[xtetx]

Just done one on mine.

Absolute nightmare as it's so tight to work at the back of the engine surrounded by pipes and minimal space.

2 x bolts on the master cylinder in to the servo. Think these are 13mm.
You can
Remove the bottle but it is near impossible to remove the bolt that holds the bottle to the cylinder.
I actually put the spanner underneath the master cylinder and got the back bolt off with some serious will power and patients.

There are 2 x hard lines with nuts that are attached under the master cylinder to remove. Think these are 11mm and you will need definatly need a stubby spanner for this as the charge pipe at the back of the engine gets in the way.

You are best to get a syringe and remove the brake fluid from the master cylinder bottle first.
Remove the cylinder.
Fit the new cylinder and ensure you get the piston from the servo in to the master cylinder as if you miss it you will have to redo it all again! Trust me I know haha!
Then once you have fitted the new cylinder you will need to bleed the system. Make sure you use a bleeder kit as you don't want to destroy your new master cylinder.
Bleed the master cylinder, bottom bleeding nipple first, then the top one.
Then bleed all brakes furthest from the master cylinder so back near side, back offside, front near side, front offside.

Job done.

[matt@onlychargeddubs]

As above, crap job!

You shouldn't need to bleed the ABS and I wouldn't even bother trying unless you've got a proper bleeding machine

[morepatrols]

Top notch reply lads, appreciate it.

What time frame would you put on the job, I have done most things to cars over the years and practically rebuilt my house from scratch (I mean it!) so I am handy. Just seems that access is impossible.

I have seen people on youtube pre bleeding the master cylinders (which dont have bleed valves) guessing this isnt necessary.

--- I actually put the spanner underneath the master cylinder and got the back bolt off with some serious will power and patients. --

Xtetx are you saying you got a spanner or socket set under the master cylinder to the offside bolt? Just seems well tough with virtually no access. Was it as hard to refasten the new one, or did you fit the new one without the reservoir on top?

--- I actually put the spanner underneath the master cylinder and got the back bolt off with some serious will power and patients. ---

is there a definitive way of knowing you have got it in the right place? Did you change the seal?

Cheers again lads, still not looking forward to it but at least I know it can be done!

Paul

[xtetx]

It depends how quickly you get the master cylinder off!
I would say around 3 hours.
You could break off the old master cylinder bottle to gain access to the bolt as I doubt anybody could get it off as it is such a tight space.

I gained access from the back and under the cylinder without removing the bottle. I used a spanner as a socket is impossible to get on with the little room available.
You know you have got the bolt by running your hand under and feeling (that's how I did it, serious nightmare.)

Which seal do you mean?

I didn't bleed the abs pump and my brakes are fine.

[mar_k]

Are you certain its the master cylinder?
May just need bleeding properly, They are a PITA to bleed, Requires pressure bleeding and also the 2 nipples on the master cylinder need bleeding too.

I messed mine up trying to bleed the old 'pedal up, pedal down' routine.
Had next to no pedal, Pretty much how you describe.

I had the brakes pressure bleed properly buy a garage that knows VW's and the brakes were better than ever.

[Prawny]

I've done a few in situ and it is entirely possible.

I've not removed the fluid res from the top at all and managed it with simple halfords socket set tools each time.

On a stock car you'll need to remove the charge pipe and bracket, access to the 11mm fluid connections underneath is from the turbo area across, very slow progress though.

Access for the MC to servo bolts is by using a 13mm deep socket on an extension and slotting it in from the front between teh coolant bottle and cambelt cover. Again slow process but entirely possible.

it's taken me 60-90 minutes to do the swap typically in the past, not including bleeding the system afterwards.

with the engine out it takes 5 minutes 

[VeeDubLuke]

Hi there I have a VW tdi pd 110bhp engine runs beautifully, however my brake pedal is spongy...
the brake pedal was going to the floor so I ordered a new brake master cylinder (which needed EPS) off a suppliers but had no luck the brake pedal is still spongy after fitting it and bleeding out the system several times. thinking it may be the masters cylinder being faulty of the shelf, I ordered another one and I have bled the system out eight times and the brake pedal is still spongy and going to the floor while the car is running (when the engine is not running the pedal goes hard) could anyone help me in assessing this is the cure to this problem?