Had problems bleeding front caliper on '90 BMW 325is

[nel]

I bought this car a few months ago, and have been changing out all the fluids. This weekend I tried changing the brake fluid. Old fluid in the reservoir looked old, discolored. There was even residue on the bottom of the plastic reservoir.

I suctioned the old fluid out of the reservoir, replaced with new and repeated a few times to get rid of as much of the old as possible. Then I put my Motive pressure bleeder on it at 10 psi. The rears bled fine, but the driver's front didn't bleed at all. I removed the bleed valve and there's just a miniscule trickle of old, black-colored brake fluid. The passenger side doesn't bleed well either but the flow is a tad more than the driver's side.

I suspect a blockage and was planning on removing the hose from the caliper first and working my way up. I've never done this before so does anyone have any tips or advice?

Funny thing is that the brakes work fine--good stopping power so the fronts must be working.

 

[Tosh]

Don't open up any lines, as you will introduce air. What happens when you try to bleed the calipers the old fashioned way: by having an assistant steadily push the pedal while you crack open the bleed nipple? You may need advice specific to BMW: check those forums. But don't open any lines: a blockage is unlikely. Personally never used a pressure bleeder. I like the Mityvac...

 

[nel]

Problem solved. I loosened the brake hose at the caliper and it seemed to bleed okay, so I removed the bleed valve--again, very little flow. Finally, I probed the hole with a pick and must have removed some gunk because it's bleeding fine now.

You should have seen the old fluid--very dark, especially at the clutch slave cylinder.

As TxGreaseMonkey says in a separate thread, it's best to flush your brake system every 2 years or so. Looks like the previous owner had been neglecting this maintenance for a long time.

 

[srivett]

It sounds like you are missing the bleeder caps? They are a pain to track down for a reasonable price.

Steve

 

[srivett]

x

 

[labman]

I would replace the 15 year old rubber parts in the caliper the first pad change. Easiest way is rebuilt calipers. The hoses might be another doubtful part top replace before problems.

 

[nel]

Labman, I agree on rebuilding the calipers. Since I just changed pads, it'll be awhile. All the bleeder caps were intact--just a matter of negligence on the part of the previous owner.

 

[Tosh]

Right, no sense in looking for places to spend money. They'll come soon enough on their own. I think you should spend some effort on protecting all the plastic, vinyl, and rubber parts, as they deteriorate naturally over time, and you won't notice until something cracks...