Jetta brakes-bleeding

Don't mean to offend you, but how are you bleeding the lines? Also, when you let the lines drain, did you remove the cap off the reservoir?

Darryl.

Buy a power bleeder and use that instead of pumping the brakes. They work great.

Just a guess but have you followed the procedure to adjust the e brake? As I recall on my 99.5 jetta after installing pads you eather pull the e brake or push the pedal first but I don't remember the correct one and it's importance was stressed. Check your Bently. Also instead of pumping out the fluid try another method. One is to make and attatch a small garden sprayer with fluid in it and then pump the sprayer and pressureze the whole system and then bleed. Another procedure is attatch a small vacume pump, hand or motor powered, to each wheel cylinder and suck the fluid/air out. Also I think I read a quart a wheel in the bently.

JoBo

Are you getting any help bleeding it, or you are doing this all by yourself? Bleeding should be: With a Helper and the bleeder closed, the brake pedal is pumped a few times and held down then the bleeder is opened observing fluid flowing through the clear hose into a bottle of fluid. Or a one-way valve on that hose helps. I usually open the lines one at a time at the new brake master and make sure I bleed that before I attempt to bleed the wheels in this order; RR,LR, RF, LF.

Or a power bleeder and you can bleed by yourself easier. ;-)

Some have talked about gravity bleeding, but I think it takes longer and air bubbles may get trapped in places. Not sure on this though.

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

All questions are fair game...thanks all for your suggestions. More detail:

First, I do not much want to buy a machine although I'm sure they work wonderfully. I live a space constrained existence, and do not imagine myself doing more brake work for a long time. Once this gets done that is.

The e-brake is not yet connected.

I don't quite get the garden sprayer idea -- if I were to do this to the individual lines at the master cylinder, wouldn't I still have to bleed it out anyway once I reconnect the lines? Otherwise I need to seal the garden sprayer to the reservoir cap somehow...??

"When I let the lines drain...": when I left it overnight with one caliper line unconnected, the cap might have been off the reservoir, I forget. But not much fluid was collected, and once everything was assembled, I refilled the reservoir before trying to pump it.

On how I did the bleeding:

I have pliers clamped (fairly gently) on the regulator at the back holding the rocker plate on it in the position it would be if I were driving with a ton of bricks in the trunk.

I had an assistant help me do one of two things in the three or four cracks I took at bleeding the system:

- open bleeder, pump brakes gently several times, until no bubbles are seen coming out, holding pedal down at end and closing valve

- have assistant push pedal down once and hold, open bleeder, close bleeder when flow stops watching for bubbles, release pedal, repeat.

I will certainly try the assistant pump pedal several times and hold, open bleeder, close bleeder when flow stops, assistant release pedal, repeat method if that is substantially different than what I already did. And perhaps I just haven't been sufficiently patient. How many valve cycles is reasonable for this, and is it important to do it quickly? I don't think I did more than four or five cycles of valve openings and closings on any wheel since I was never getting any bubbles by that point, and didn't want to empty the reservoir, but maybe that was just the calm before the storm.

I believe the reservoir cap was generally on, although maybe not screwed down tightly, when I was bleeding.

I did the wheels more or less in the order mentioned RR LR RF LF.

One respondent mentioned a quart of fluid per wheel, I haven't run nearly that much through yet, which makes me ask: is it kosher to feed the mostly clean fluid you bleed out the brakes back into the reservoir, or would a smart person just throw it away (how do you dispose of it, like motor oil? I live in Mass.)? I have long since removed all the of the dark cloudy stuff that was in there when I started, but I still get the odd flake or bit of crud coming out.

Good day, Peter.

You can get "speed bleeders", bleeding nipples with a built-in check valve for easy one-man bleeding. Check

stay on the car and should not affect your "space constrainedexistence". You can also get similar check valves that you insertin-line with your bleeder hose. With both methods, I worry (perhapsneedlessly) that some small amount of air may bleed back into the system(around the nipple threads) on the pedal up-stroke. I usually finish ofwith two or three "pump, hold, open valve, close valve, release" cycles(kind of defeats the one-man operation promised by the speed bleeders,doesn't it?).

Throw it away. Both the Bentley and the brake fluid bottle has stern warnings about this.

Where I live, (northern CA) you can make an appointment with the county for hazardous waste drop-off. Whenever I have accumulated enough motor oil, brake fluid, paint thinner etc. I make an appointment and drop it off. It's free.

Peter,

Too bad if your first m/c (may have) failed because of bottoming out...that is a shame.

For this new m/c, did you bench bleed it at all, or did you install it, and then just fill it and start the wheel bleeding process?

I had an 81 Rabbit (with probably a similar m/c to yours, and probably similar m/c available at Pep Boys/AutoZone etc.) When I had to replace the m/c, I went through three reman units from Pep Boys before I had to buy a new one ($110 instead of $35, and this was in 1990). The problems I had with the reman units were that the seals at the push-rod end of the master cylinder were not able to seal properly since the cylinder had been honed out (as part of the reman process) The result was that although I was able to get the thing bled, I kept loosing brake fluid rapidly but without a drop on the ground. Eventually I discovered that the vacuum booster was inhaling the fluid from the m/c!

So, be aware that there's a possibility that a reman won't work out and you'll have to spring for a new one.

Good luck, Arthur P.S. Sorry if someone already mentioned these possibilities, I didn't read all of the responses to date very carefully.

Sounds like I didn't bleed it for (nearly) long enough for a m/c replacement. No I did not bench bleed the master cylinder. I bolted it on, installed the brake lines, then popped the old reservoir on and filled it. Bench bleeding presumably would involve just sitting it level and pushing the piston by hand with the reservoir installed until fluid squirts out the brake ports? Shame if that's necessary as it's a damn sight easier to put the fittings back without the reservoir installed. I don't think any special bench bleeding "kit" or fittings were provided as one person suggested but I'll have a second look.

I will certainly be on the lookout for disappearing fluid once it's together. I am crossing my fingers that this m/c is serviceable.

Thanks, Peter.

Arthur Russell wrote:

You can slightly loosen one brake master line at a time at the master and push on the brake pedal. Loosen it just enough to try to let the air out and barely enough to let the fluid out with pedal pushing difficulty. So actually the line is almost bolted down completely. ;-) Do this to all the brake master lines.

I forgot was this a GLI with rear calipers? You have to make sure that the are no air gaps between pads and rotors. Caliper pistons may push out but then retract creating air gaps and making the brake pedal travel further down.

Incorrectly installed brake shoes could create the same problem too!

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

No I did not bench bleed the master cylinder. I bolted it

If you didn't bench bleed then that is most likely your problem

I don't think any special bench bleeding "kit" or fittings

I been involved in replacing about 4 master cylinders now and they all came with explicit instructions on bench bleeding and a bleeder "kit". All the kit consists of is two cheap plastic hoses and fittings. You hook up the fittings to each half of the master cylinder then the hoses are routed back into the reservoir. You then pump the piston slowly by hand until only bubble free fluid is going to the master cylinder. The instructions on the last master cylinder stated that #1 reason for problems with new master cylinders was not bench bleeding them. If yours didn't come with the kit I'd go back to where you bought it and have them pull another one off the shelf to see if yours was just missing. I bought several auto parts over the years that were missing parts/defective because they were previously sold and returned to the self. In fact now that I think of it, one of the master cylinders was missing the big O-ring for the booster end due to this.

HTH

Steve

Peter: I cant believe no one had mentioned this to you yet, but you have to also bleed the booster. Have you done this?? Once the brakes are bled(and between you and me, I agree that buying brake bleeding devices is unneccessary) you need to also bleed the booster, the bleeder screw is the same as on the brakes. Hopefully that helps you. I dont see the point in buying brake bleeding equipment for a job that is easily done using two people, if you have the people power, its just as quick to pump pump pump hold and crack the screw. I do have a bleeding device as my girlfriend is sometimes unwilling and/or unavailable, but you dont really need one. IMHO.

J

||Peter: I cant believe no one had mentioned this to you yet, but you ||have to also bleed the booster. Have you done this?? Once the brakes ||are bled(and between you and me, I agree that buying brake bleeding ||devices is unneccessary) you need to also bleed the booster, the ||bleeder screw is the same as on the brakes. Hopefully that helps you. ||I dont see the point in buying brake bleeding equipment for a job that ||is easily done using two people, if you have the people power, its ||just as quick to pump pump pump hold and crack the screw.

Just be sure the pumper does not bottom out the piston in the MC bore. That can ruin the seals and put you in the market for a enw MC.

|| I do have a ||bleeding device

I've done bleeding a lot of different ways. Usually I use gravity bleeding. I just bought a vacuum bleeder, which I think is the best of all possible choices.

- Easiest on the hardware

- Does not force air into the fluid like a pressure bleeder (the pro versions have a rubber bladder to prevent this)

||as my girlfriend is sometimes unwilling and/or ||unavailable, but you dont really need one. IMHO.

Don't need a girlfriend, or a bleeding device? [avoiding the obvious opening] Texas Parts Guy

Could you elaborate on this? I replaced the MC on an '87 GTi and I can assure you that the booster was not in any way connected to the hydraulic system. What am I missing here?

Jim B.

I straightened my rookie cap today and started over trying to do everything very carefully. I'm a lot closer but still not there. From replacing the rear pads a few years ago I think I remember that when everything is bled and all the boost is gone, the pedal stops after only about 1/4 of full travel. Right now I'm getting it to stop about 1/2 or 2/3 of the way down after 3 pumps, first pump still goes nearly to the floor; I've bled many quarts of fluid through the system. The DOT4 stuff the reservoir says I should use is hard to find for some reason as well. Everyone's always out of it. I've cleaned out three stores now.

I did have the parts to bench bleed the master cyl so I did that. I also noticed that the reservoir does not snap down flush against the seals in the reman m/c like it did the original. But I don't think it seals on the bottom face of the reservoir, rather on the two barbs, so that shouldn't matter.

I bled all the lines again, taking out 12-16 oz of fluid per wheel the first time around. The pedal at this point was still going all the way to the floor. Then I released the rear brake pressure regulator, after which it built up pressure more easily. I went around and bled everything again for almost as long and got some more bubbles out the back.

After all this, when bleeding, we noticed that after the 3 pumps and opening the valve, the pedal sinks when the rr or lf caliper is bled, but not when the others are bled, even though there's always pressure and fluid always comes out. I guess this is telling me that there's still some kind of big bubble in either the lr or rf line or their common m/c section? Maybe I ruined my good work with the bench bleeding tilting it in or installing the lines. FWIW the lr caliper isn't clamping much without 4 or 5 pumps. The rr seems to work.

Also, the pedal still sometimes catches on the way up, with the sound of something sucking or squirting up front. Don't know what this could be. Don't like it.

Final scary thing, sometimes when pumping the pedal will get very stiff after the few pumps, but then with a sound the pedal will suddenly sink most of the way down. Scary because I imagine that could be the stupid m/c leaking again, but in a different way than the sinking pedal from before the replacement, and I'm looking for a high level of confidence in my brakes. Maybe this could also be a bubble phenomenon. Once again, I don't want to start over.

I think it's driveable now; I'm real close to throwing in the towel and calling in the pros. I'm testing the patience of my assistant for sure!

Thanks all, Peter.

snip

I have seen some NEW brake masters that were bad, although they were for a T3.

I probably would exchange that brake master for another one. Was it new or remanned? I prefer good brands that are new like ATE.

When you bleed just leave that proportioning valve alone, but make sure the lever moves freely. Also with care you could isolate each wheel caliper by carefully clamping the hoses closed to find out if the calipers or the master are creating your low pedal problem. Hoses might swell when the pedal is depressed, or those air gaps between the pads and rotors. Of course I am assuming that you would see any brake fluid leaks coming out of the lines. ;-)

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

I been watching your issue and the only suggestion I have is "are you sure you put things together correctly"?. I have never seen a master cylinder go bad from all the fluid draining out overnight. If you have no air coming out when bleeding then I would look to see if the pads float freely within the calipers, and there is no space between the pad and rotor. Are the bleeders on top of the calipers? Sounds dumb but I have seen calipers installed on the wrong side of the car. Hard to do in the rear but easy with the fronts. But... sounds like you need someone else to check it out.

Easy to do in the rear if you have A3 calipers on an A2.

:-)

||Easy to do in the rear if you have A3 calipers on an A2.

What would be the advantage of switching to A3 calipers? Texas Parts Guy