# B5 passat 1.8t loss of brake pressure... any ideas?



## MyCarIsRed (Aug 9, 2004)

i have a 99 passat 1.8t. 4 wheel disc, abs. yesterday i was driving in moderate traffic and the pedal starting going soft. before long the pedal was going straight to the floor. i was able to pump the brakes to get enough pressure to stop and pull over. i sat on the side of the road for about an hour trying to figure out the problem before driving again. the brakes were back to normal for about another 10 min, then went soft again. i limped it home and today drove it for about 15min to a friends house to help look at it. the whole way there it felt normal. 

has anyone ever heard of anything like this or know what it may be? we think it may be a bulging line or a small leak in one of them. it's hard to tell because it's been raining here and everything is wet, but there is some obvious wear on one of the front lines. 

Any help is huge. thanks in advance vortex :thumbup: 

p.s. until this is resolved i'm driving a chrysler minivan so lets get this figured out quick:laugh:


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## KG18t (Aug 9, 2006)

Does the pedal go smoothly to the floor? Or does it hold a bit of pressure and then go down?


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## MyCarIsRed (Aug 9, 2004)

when it's gone it's gone. it just drops. then i can pump it up and it'll hold pressure and slowly drop


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## ps2375 (Aug 13, 2003)

master cylinder would be my first guess. Have you checked fluid level and for leaks around car?


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## MyCarIsRed (Aug 9, 2004)

fluid level is good. doesn't seem to be losing fluid. master isn't leaking or anything. the line is really worn. i don't think it's leaking, but it is worn to the point where it could be bulging under pressure when it's hot. that was my thought. i ordered new lines because it definitely needs them regardless of whether or not it's the root of the problem. i didn't think it was the master because it still has full clutch function. wouldn't the clutch be affected? i thought it was controlled by the same master cylinder? there is a fair chance i'm wrong on that.


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## ps2375 (Aug 13, 2003)

The fluid for the clutch is from the same reservoir, but they have separate master cylinders.


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## MyCarIsRed (Aug 9, 2004)

gotcha. so this sounds like a brake master issue to you? i'm pretty weak in the brake problem diagnosis area. as soon as i figured out that it was normal when cold and soft as it got hot i just scratched my head and threw up my hands. 

btw, thanks for all of your help... this minivan is killing me.:facepalm:


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## ps2375 (Aug 13, 2003)

If one of the lines are worn, I'd deff do that first.:thumbup:


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## MyCarIsRed (Aug 9, 2004)

that was the idea. the lines are bad so i was going to take care of that if for nothing else but maintenance. I just picked the car up 2 weeks ago so i'd rather be on the safe side with this stuff because i don't know the history. :thumbup:


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## EuroSportChicago (Jun 9, 2010)

If you havent spotted any leaks or messed up lines, check the pistons on the calipers for the seal, if its bulging/getting stuck. it could leave bubbles there if it is not releasing the correct way


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## spitpilot (Feb 14, 2000)

Line would break if it bulged enuff to let pedal go to the floor...If you can see no fluid leaks at the wheels....I'd bet its master cylinder seals....if one leaks it can bleed preesure interally..so you see nothing, but get no braking power..if the last seal leaks you'll be dumpin fluid into the booster..but you said "no fluid level problem"...so that points to internal MC seal leak....Gotta flush that fluid every other year...keeps crud/corrosion from eating seals in the MC/Calipers...which cost $$$ more than $10 worth of fluid every other year!


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## MyCarIsRed (Aug 9, 2004)

yeah. i'm good about maintaining cars. i just picked this one up 2 weeks ago. it's got some miles so i'm guessing it was just time. i ordered a new master and rubber lines. the ground was pretty wet where i was stranded, so i couldn't really tell if anything was leaking. everything was wet. the rubber lines need replacing regardless... they were pretty beat up. i'll do the whole job at once and never have to worry about it ever again.:thumbup:


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## EuroSportChicago (Jun 9, 2010)

MyCarIsRed said:


> yeah. i'm good about maintaining cars. i just picked this one up 2 weeks ago. it's got some miles so i'm guessing it was just time. i ordered a new master and rubber lines. the ground was pretty wet where i was stranded, so i couldn't really tell if anything was leaking. everything was wet. the rubber lines need replacing regardless... they were pretty beat up. i'll do the whole job at once and never have to worry about it ever again.:thumbup:


Git er dun


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