# MK4 GTI Leaking brake fluid! Please help



## Clintron (Jun 30, 2009)

I'm leaking brake fluid from what looks to be a regulator bolted into the side of the transmission, it has two bolts and one line running out of it and a fitting for bleeding. What is this part called?


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## GTijoejoe (Oct 6, 2001)

*Re: MK4 GTI Leaking brake fluid! Please help (Clintron)*

Brake fluid going to a regulator off the transmission?







are we sure








Do you happen to have an auto?
Are we sure this is brake fluid?
Pictures may be in order...


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## waabaah (Jun 24, 2006)

*Re: MK4 GTI Leaking brake fluid! Please help (GTijoejoe)*

slave cylinder.
it is brake fluid but are you having to fill up your clutch master cylinder?


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## Clintron (Jun 30, 2009)

*Re: MK4 GTI Leaking brake fluid! Please help (waabaah)*

No my brake master cylinder keeps going low, I think I'm losing it from there. Is that possible?


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## Clintron (Jun 30, 2009)

*Re: MK4 GTI Leaking brake fluid! Please help (GTijoejoe)*

It's my Clutch master cylinder. But I'm losing brake fluid out of my brake master cylinder.


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## waabaah (Jun 24, 2006)

*Re: MK4 GTI Leaking brake fluid! Please help (Clintron)*

two separate systems...
so it sounds like there is another leak that you must find for the braking system....but before we jump the gun... how much brake fluid are you adding to your master and how long before you have to fill it up again??
if you just noticed the fluid low "once"...and havent filled it back up, you may just need pads and or rotors. this is a common feature of master cylinders since as your pads/rotors wear, the calipers themselves will collect more fluid and hence why the master cylinder will be low possibly resulting in illuminating your red brake light.



_Modified by waabaah at 5:36 PM 11-30-2009_


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## Clintron (Jun 30, 2009)

*Re: MK4 GTI Leaking brake fluid! Please help (waabaah)*

I definitely have a two leak problem, because I have filled up my brake master cylinder twice now, about a couple weeks apart. My pads and rotors are ok, where else is a common place for leaks? Where is the clutch cylinder located? Under my brake master cylinder? Thanks again very much appreciated!


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## waabaah (Jun 24, 2006)

*Re: MK4 GTI Leaking brake fluid! Please help (Clintron)*

yeah..i think pictures will be in order here...
reason being is i just happened to try to find my clutch master cylinder and coulndt find it. i will have to do some research on what type of system vw uses for clutch disengagement.
so more then likely your filling up your brake master cylinder. your going to need to take off each wheel and inspect for wetness.


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## GTijoejoe (Oct 6, 2001)

*Re: MK4 GTI Leaking brake fluid! Please help (waabaah)*


_Quote, originally posted by *waabaah* »_yeah..i think pictures will be in order here...
reason being is i just happened to try to find my clutch master cylinder and coulndt find it. i will have to do some research on what type of system vw uses for clutch disengagement.
so more then likely your filling up your brake master cylinder. your going to need to take off each wheel and inspect for wetness. 

Atleast MK3's use the same reservoir for brake and clutch, I suspect MKIV's would be the same, its good cost down for OEM's, typically the clutch is uneffected by brake fluid level... meaning if you have a brake system leak, the fluid will leave the brake MC res., but of course the clutch won't be effected because its MC is already filled with fluid. 
Now if you lose fluid such that the level is below the clutch MC fill, than its obviously a brake system leak, if it was a clutch system leak, the fluid would only drain to the clutch MC fill level... and your clutch wouldn't work properly.
As suggested you need to understand where the leak is, worst case is its your brake MC and its leaking in your booster's shell, check all lines and calipers etc.


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## IJM (Jul 30, 2001)

*Re: MK4 GTI Leaking brake fluid! Please help (GTijoejoe)*

Yes, MkIV cars use one reservoir for both the brake and clutch hydraulic systems. When your clutch slave cylinder (the one on the transmission housing with a bleeder valve) leaks, it'll draw down the brake fluid reservoir.


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## Clintron (Jun 30, 2009)

*Re: MK4 GTI Leaking brake fluid! Please help (IJM)*

OK cool! Good to know I don't have a brake system leak also.







What is the procedure for bleeding a Clutch slave cylinder? Similar to bleeding the brake system?


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## IJM (Jul 30, 2001)

*Re: MK4 GTI Leaking brake fluid! Please help (Clintron)*

I think that's how I did it several years ago, but you should check the DIY on it. I'm sure there's one somewhere.


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## germancarnut51 (Mar 23, 2008)

*Re: MK4 GTI Leaking brake fluid! Please help (Clintron)*

Whenever the clutch slave or clutch master leak, and need replacement, it's best to go ahead and change both, because when one dies the other follows soon.
When it's necessary to bleed either the clutch or brake system, it's best if you do both systems. Contamination is usually the cause of deterioration in the brake and clutch fluid systems. So, before installing new parts, it's best to change out the old dirty fluid to try to adoid early contamination of the new part/s.


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