Brake Bleeding Problems

[gfnetadmin]

I've just finished changing front and back brake pads and rotors, having a difficult time getting the brakes bled. Along with brakes, replaced struts, Control Arm bushings, also had to replace right side inner CV Joint, so rather than fighting with the front calipers during all of this, I disconnected the brake lines and removed the calipers. When I disconnected the front brake lines, I saw how bad the condition of the brake fluid was. I've had this '96 B4 for a couple years, haven't put a lot of miles on it, I know I should have addressed the brake fluid sooner.

So I've connected my Motive Power Bleeder, tested for leaks prior to filling the bleeder with fluid. Added fluid, and pumped the power bleeder up to about 12 PSI. Starting with the right rear, all I got was a small stream of dark colored fluid. Same with rear driver's side. Almost nothing from the front passenger side, only the front driver's side seem to bleed half decent. I left both rear bleeders open while trying to bleed the fronts, nothing coming out of the rears.

Seeing the condition of the old fluid, would the gunk I saw coming from the disconnected front brake lines now prevent me from bleeding the brakes properly? Before I have someone assist with trying to bleed using the pedal, wondering if doing this would force even more bad stuff through the system?

 

[moroza]

Gunk might be clogging it, yes, but I doubt it. That said, I've never seen a bleeding tool, no matter how fancy or expensive, that was as effective as two people - one at the pedal, the other cracking open bleeder screws connected to tight-fitting clear tubes whose other end is in a jar below the level of old fluid. It's not slick, elegant, or efficient (or features in Snap-On's catalog), but it's the most sure-fire way of bleeding brakes, especially from scratch (that is, where there's a lot of air in a lot of areas of the circuit). Do one at a time, starting with the furthest away from the master cylinder (RR) and working up to the closest (FL).

Some BMW traction control systems require special tools to bleed the brakes properly. I don't know if VW ABS systems are anything like this, though I've bled quite a few VWs and never encountered problems. Still... do you have ABS?

 

[gfnetadmin]

No ABS. I did get a helping foot for a short time tonight, also raised the rear axle beam with jacks as the car is sitting on jack stands on all 4 corners, tires off, just in case the brake proportioning valve was restricting rear fluid flow.

Manual bleed process using the pedal was a little better in the back. Person on the brake pedal could feel the pedal go down when I opened the bleeders, some fluid coming out, but not what I would expect to see. I did have a piece of wood under the pedal so that the pedal wouldn't hit the floor. Front right side, no difference, no fluid coming out either using a power bleeder or using the pedal. After I lost my helping foot, I went back to the power bleeder, no fluid at all bled from the rears or the right front. Driver's side front bleeds fine either with pedal or power bleeder.

So could 21 year old brake fluid (I'm assuming it was never changed), drained at the front caliper brake lines cause something like this? My next steps?

 

[KLXD]

Have you completely removed the recalcitrant bleeder screw to see it the leetle holes are plugged up?

 

[00013cave]

Have you completely removed the recalcitrant bleeder screw to see it the leetle holes are plugged up?

Agree with this. The hole can easily get clogged after time. You should remove them and you may have to drill it out from both ends and blow through with air

 

[oilhammer]

Sometimes removal of the bleeder screw altogether and stomping down hard on the pedal with force any crud out of the hole. And you can check the bleeder screw itself with a light, and if necessary a tiny drill bit to clean it out and blow it clean with some brake cleaner.

We have a BG branded power bleeder here at the shop, it works awesome, but even it sometimes doesn't have the oomph to push out a blocked up hole.

 

[206danebmx]

I had this same problem when bleeding my brakes too, I believe I have the same motive power bleeder. The rears wouldn't really bleed at all, the fronts a little better, its seemed to help a little if I pushed on the brake pedal with the bleeder hooked up but ultimately I ended up using the old reliable two person manual bleeding.

I wonder if there is some design of the brake system that prevents the power bleeder from working well on these cars. I used the same bleeder on my BMW and it was a dream!

It could also just be some nasty clogged lines? I had brand new rear calipers on mine too when bleeding the B4.

 

[aja8888]

Sometimes the soft lines will swell inside and clogs will make it worse. I always change out old soft lines when doing a complete brake job on an old car.

 

[hey_allen]

I had to pull 3 of the 4 bleeder screws on my Jetta when I last worked on the brakes, since they had a nasty buildup completely blocking the passage through the screws.

If I remember correctly, I ended up having to drill the hardened mess out of two of them.

As a preventative measure, I did add rubber dust caps to them afterward. They are cheap and available from most auto parts stores, though often not out on the shelves.

 

[gfnetadmin]

Thanks to all who have offered advice on my brake bleeding problem. I managed to get clean fluid flowing from three calipers by manually bleeding using the pedal. Only the front passenger side refuses to bleed. As suggested by a number of members, I removed the bleeder screw from this caliper that doesn't bleed, it was partially plugged, but was also dry as a bone, no sign of brake fluid anywhere in the area where the bleeder screw threads into the caliper. While I was trying to bleed this caliper manually, I could feel the brake line pulsating as the brake pedal was being pumped, but even with a brand new bleeder screw, no difference.

I'll give Oilhammer's suggestion on applying the brakes with the bleeder screw out a try tomorrow, also will change out the soft lines as a preventive maintenance item, they didn't look so good either, thought about replacing them when I was putting things back together.

I'm also questioning the Motive power bleeder, as after I got fluid flowing from the rear calipers using the pedal, I went back to the Motive, and couldn't get anything from either rear caliper, same as someone else here mentioned. Strange, as I bought this Motive bleeder new a year or so ago to bleed brakes on another B4. At that time, everything on that car was new, Master Cylinder, all new metal and rubber brake lines, proportioning valve, and calipers, I had no trouble at all using the power bleeder, thought it was a pretty good investment. Could be a case of hardening of the brake arteries on this car?

Again, thanks to all who responded.

 

[oilhammer]

Just remember that the power bleeders cannot come anywhere near the pressure post-m/c that the hydraulics get from normal brake operation. That's why they are fine for normal fluid flushing PM, and even for service on cars that perhaps are newer and/or have no issues with neglected gunk in the system.

But on something that is 20+ years old, that perhaps did not get the TLC it should have in its past life and is now being resurrected, they may not always work as intended.