# 2001 VW Golf: ABS Brake bleeding



## iblackford (Sep 19, 2013)

Hi All, I am writing for a friend, we worked on his 2001 TDI Golf recently to fix a right rear brake caliper. 

Background: Right Rear brake caliper had seized. E-brake would not work either as the piston would not self-return. 

Actions taken:
1) Caliper was removed (banjo bolt removed) and removed from the car. 
2) Caliper was torn down. Piston, bore, and all sealing surfaces polished with 1000grit wet sandpaper and rebuilt. 
3) Caliper was put back onto the car and the banjo bolt reinstalled. It was then that we realized the bleeder screw was siezed solid, and cross threaded from a previous repair. 
4) Attempts were made to bleed the system through the banjo bolt. We got partial hydraulic brakes, no leaks, but all air could not be removed from the system. 
5) E-brake now worked. 
6) Caliper was removed again. Bleeder screw was drilled out. Care was taken when drilling and no sealing surfaces were damaged from drilling. Small amounts of thread were damaged. 
7) Since the bleeder screw was cross threaded, the thread was cleaned (M10 x 1.0) up with a tap. A new bleeder screw was installed, but we were not confident that the threads were strong enough to seal correctly. 
8) Caliper was rebolted to the car. Attempts to bleed with the new bleeder screw resulted in stripping of the remaining weak threads. 
9) Bleeder screw hole was tapped to 7/16" x 20 for using a larger bleeder screw. We used a marker on the bleed screw seat of the caliper and confirmed that the new bleeder screw was mating to this seat correctly. 
10) Caliper was rebolted to the vehicle and another bleed attempt made. During this bleed procedure, the pedal suddenly got firm. No amount of pushing on the pedal resulted in fluid going to the rear caliper (even through the banjo bolt..). All other wheels work fine. 
11) We then found through forum searches that the ABS system may have air in the system. We made an RS232-->OBD2 cable and installed VAG-COM. 
12) By running the VAG-COM ABS tests we could hear the ABS pump engage and disengage. 
13) During the bleed procedure, (NOT while it asks you to open the bleeders and pump 10x, but just before this) the pedal got soft for a few moments. During this few moments we were able to resume our bleeding. ABS output tests did not give us the same soft-pedal. 
14) We cycled through the ABS bleed a few times and used the soft-pedal moments to bleed the rear brakes. We found that the bleeder screw leaked air in slightly even when in the closed position. The bleeder screw was further tightened until it better seated in the caliper and did not leak in the closed position. We now have partial hydraulic brakes on this caliper during this soft-pedal condition. No hydraulic brakes on this caliper in normal hard-pedal conditions.
15) Vehicle battery was removed. Hard pedal condition existed. 
16) Battery attached and rear wheel was put back on. Vehicle was driven with no right rear brakes. He reported that the other 3 wheels were much more responsive than they had ever been (If the ABS system had some air in it previously, did we now purge some of it?). This is the current status of the car. 

Questions:
1) What could be possibly causing this hard pedal condition? Why would the right rear wheel be locked out? 
2) What is the ABS system doing during the bleed procedure that could cause our soft-pedal condition? 
3) The ABS bleed procedure calls for loosening of the front right and front left bleeder screws. Is this necessary? Can any bleeder in the system be used? We were reluctant to touch the other bleeder screws as they may be stuck. 

Thanks for any help that can be provided.


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## dogdog (Jul 26, 2007)

<
13) During the bleed procedure, (NOT while it asks you to open the bleeders and pump 10x, but just before this) the pedal got soft for a few moments. During this few moments we were able to resume our bleeding. ABS output tests did not give us the same soft-pedal. 
>

this is something new, maybe to newer model years able to cycle abs test via vag-com as bleeding brake lines. what I had to do when rebuilding my rear brakes / lines , I had to follow the sequences to completely bleed air out of the braking systems a few times. Maybe you can get away with short cuts but never heard of via vag-com cycling the abs units.



In the manual. Do it via some one pumping the brake (2 man job) or with one of those pressure bleeders from ECS tuning. There is no # of times to open and close, it is pump till you get all the airs till you don't see air bubble flowing from the hose properly connected to the bleeder screw. and never reuse the fluid from the bleed.

ITT Mark20 IE abs module system. 
bleeding sequences are
Right Rear
Left Rear
Right Front
Left Front

ITT Mark60 IE abs module system
Bleeding Sequences are
Left Front
Right Front
Left Rear
Right Rear


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## dogdog (Jul 26, 2007)

Anyone correct me if my memory serves use common sense. 
The manual bleeding procedure is 

follow the recommended sequences for your abs module
car off/ caliper remounted to car with disc / drum, tires are optional
have some one pump the brake till it is firm then hold it down.
The other guy connects a clear tube to your bleeder attached to a plastic bottle to collect the fluid
use a proper sized wrench crack open the bleeder screw till the fluid start flowing....
if you have air in system, you would see bubbles in the stream.... might also see bubbles if you attached the clear hose loosely to the bleeder screw.
watch your fluid level never let it drop to low /empty on your brake ....reservoir 
close the bleeder screw when the brake travels all the way down to the floor before he/she/it lifts the brake paddle, so air don't get suck back in from screw.
repeat pumping and bleeding till stream flows without bubbles.

continue with all 4 brakes in the recommended sequence, and repeat again for the 2nd time should be faster.
mount tire and check make sure it is not rotating once brake is pressed. check all 4 wheels / brakes. I used the breaker bar and hand try to rotate tire while the car is jacked up and some one pressing the brake. repeat the bleeding if necessary.

after you have done this manual steps, probably will sprint to fork over the $$$ for that power bleeder. they have a nice video how to also for power bleeding.


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