# cant get brake pressure! 88 jetta 8v



## 206929rr (Oct 5, 2009)

so i was having problems getting any brake pressure and was losing brake fluid( car is an 88 jetta gl 8v). After lookin over the car and not finding any visible leaks, it was suggested that the master was leaking into the booster, and thats why i couldnt see the leaks.
after replacing the master, we still couldnt get any pressure and was still losing fluid (empties the master resivior in less than 5 miles). i went through every thing i could think of. no leaks at the master, the lines, calipers, wheel cylinders, or rear proportioning valve.
so before i rip the whole brake system out, any thoughts?
thanks,
Sean


----------



## germancarnut51 (Mar 23, 2008)

*Re: cant get brake pressure! 88 jetta 8v (206929rr)*

If the brake fluid is leaking out in 5 mies of driving, obviously there's a leak that you have not found yet.
Have you personally checked every inch the the brake lines from master cylinder to caliper or wheel cylinder?
Did you install a brand new or rebuilt master cylinder or one you got from a junkyard?


----------



## 206929rr (Oct 5, 2009)

*Re: cant get brake pressure! 88 jetta 8v (germancarnut51)*

well heres what i found. i used to work at the les schwab i took it too and they let me use one of thier lifts from time to time. one of the guys was helping me out and he checked the wheel cylinders. he said they werent leaking. i asked him if he pulled the drums to check, he said he did. well apparently he just looked at the back of the drum and saw no moisture. when i pulled the drums this morning at the house to do some investigating, fluid dumped out. they were gushing fluid! so that seems to be the problem, replacing them on thursday, ill post the results thursday afternoon or arounf midnight that night. when i asked him why he said he pulled em, he said that he just assumed they were fin cuz the outside was dry. just goes to show that knowing someone, alot of times theyll half ass it just cuz ur not a customer. guess thats what i get for letting a "professional" mechanic help and not doing it on my own


----------



## 206929rr (Oct 5, 2009)

*Re: cant get brake pressure! 88 jetta 8v (206929rr)*

so yea replaced the wheel cylinders and still no pressure after letting it drip for a long time and mutiple bleedings














. only thing i can think of is the rear proportioning valve is holding air in the rear passenger line, because when you bleed the brakes, all the others shoot fluid out with good pressure, but that one only trickles, so ill intsall the new one in the morning and let you guys know what i find. oh yea and it was only leaking out the driver side wheel cylinder, thinking there might be a connection


----------



## germancarnut51 (Mar 23, 2008)

*Re: cant get brake pressure! 88 jetta 8v (206929rr)*

Are you bleeding the brakes with the rear of the car on jackstands? If so, do you have the stands on the axle beam so the rear axle and wheels are up where they sit when the car is on it's wheels, OR do you have the stands on the car body, and are letting the wheels droop down?
The reason why I ask is because the proportioning valve is designed to restrict flow to the rear wheels when the back of the car is raised (like the car is nosediving with the brakes on hard). If this is the case, you are not going to be able to bleed the brakes properly. To bleed the rear brakes you need the stands on the axle beam OR the car's rear wheels on the ground.


----------



## 206929rr (Oct 5, 2009)

*Re: cant get brake pressure! 88 jetta 8v (germancarnut51)*

actually we held the valve open with a bunjee cord, so that should replicate the car being on the ground as far as the valves is concerned. and it was just the rear pass drum that wasnt bleeding well, the others were fine


----------



## 206929rr (Oct 5, 2009)

*Re: cant get brake pressure! 88 jetta 8v (206929rr)*

i have a webb 276 cam. would the cam duration be large enough to cause a loss in vaccum so no pressure? i know some of my friends have had this problems in thier muscle cars with big cams. just a thought.


----------



## 91JETTAboy (Mar 16, 2008)

if you say the car is loosing fluid then you have a leak and its nothing mechanical.
it doesnt matter if its leaking a drip every 10 minutes or its squirting out all over, its letting air in your system causing no pressure. pump the pedal for a while and see if any spots are wet, that means all over your lines and calipers and m/c and booster
if you find a leak fix it and bleed them

or maybe they just have to be bled to begin with
do not have the car in the air when bleeding
if you did replace the m/c the pushrod on the booster could be missing
did you bench bleed the m/c before you put it on?
all you the BPV does is adjust the level of braking to the rear
also make sure all your calipers pistons move
also there are SIX soft lines on your brake system, make sure they are not expanding from being dry rotted



_Modified by 91JETTAboy at 8:18 PM 12-15-2009_


----------



## 206929rr (Oct 5, 2009)

*Re: (91JETTAboy)*

we bench bled the master, bled the brakes 3 times, and all the caliper pistons are moving. wouldnt holding the valve open replicate the car being on the ground? and from what i can remember its not losing fulid anymore. like i said, the only real symptom i can see is the rear right having bo pressure when you bleed the brakes. it just dribbles out while the others shoot a strong jet of fluid. so what im thinking is theres an air pocket stuck somewhere in that line or in the propotiong valve that is compressing when you step on the brakes. sometimes theres a high, hard pedal with no give, just a rock. and others it just hits the floor. i know theres air in the system somewhere but it dosent matter how many times you bleed them, gravity bleed them or anything. its very sporratic


----------

