E30 Front Calipers - Can't bleed, pedal soft

[Mikedsvt]

Hi guys. Newbie here...

1988 325i

Morther in law had this car and gave it to us, sat for a 2-3 yrs and knew it needed work but 0 rust. Drove it 150ish miles and the brake peddle left something to be desired. I ordered rotors and pads and then started to pull her apart.

The ball joints, tierods and front shocks were junk. Ordered replacement kit from FCPEuro. Full front end was rebuilt, I've done prbyy 20 cars brakes in my life. Took for a test drive and locked them up in my gravel driveway as a test. Then the peddle lost all stiffness and brakes were shit. Pull all 4 corners and attempted to bleed...

Rears would bleed with no issue. Fronts had barely any fluid even with the bleeder fully out. Read on here a few thing suspect master cylinder, abs or the rubber supply lines collapsed. Thought 100% possible on the lines as I propped calipers up during the work and they fell a couple times. Figured old hoses from 88 may have collapsed. I cut tepathe line and pushed the brakes and got a stream of fluid. Not super powerful but plenty of fluid coming out. Clamped it off and picked up new lines.


Installed both sides and on passengers side the caliper piston was fully extended and the inner oad was missing. Some idiot (me) for the forst time ever left a pad out as i found itbin my magnetic tray.

Try to bleed the fronts, still not much from bleeders. I pull bleeder fully out and still not much fluid either side. So what now? The reservoir has plenty of fluid, I can try power bleed tmrw. But do I target the master cylinder? How do I test it, how do I bleed the ABS pump? What issue may I have caused? Replace calipers?8

[thebutterson]

I've had issues like that before. In fact, just a few days ago I was bleeding and had almost no flow out of a rear caliper. I pulled the bleed screw out and still almost nothing. Then I took some safety wire and started poking around in the hole and I freed up some debris and then all the sudden I had LOTS of flow.

These old calipers get rusty muck in them if they don't get bled for a long time. It's relatively cheap to get a reseal kit and pop the piston out and clean them. I've had several calipers improve operation from doing this. It's also cheaper than a reman'd caliper that comes shiny silver and then quickly rusts.

It's also possible that during your brake test one of the seals in the master cylinder was damaged. There have been reports of this when exercising the MC in areas that it hasn't slid through in a long time. A bad or worn seal in the MC will not allow you to generate as much pressure as you should. I've had this happen to me too.

[bangn]

sounds like a cactus brake master, not uncommon. Taking the nipples right out is going to allow a lot air to get in the system too which wont be helping. Given the master is 35 years old I would be replacing it, good chance even when its bled up your car might start releasing the brakes slowly at the traffic lights. The rubber hoses wont collapse, but they will crack from age and leak.

Given the issues you're having I would be looking for a vac bleeder if you can or someone with a vac bleeder (workshop). Although the two person approach works, it sucks and can cause a lot of headaches for the inexperienced and needs to be done exactly right or you will never get all that air out and chase your tail.

[Mikedsvt]

Bangn - what is the exactly right way? I've done all 4, RR, LR, FR, FL in that order. Hoses have been replaced, if I bled with front caliper line unhooked fluid would come out. Not under ton of pressure but it would. Pump the brake and hold, Crack the bleeder, close bleeder release pedal.

I think or hope the master and full bleed will fix it

[e30vert]

Good chance you have sludge build up in one or more calipers. Mine were sludgy years ago before I pulled all the calipers and rebuilt them with new seals and other parts. I also polished the pistons slightly.

[Mikedsvt]

For anyone who finds this post searching for the same issue here is am update.

Purchased a new brake master cylinder. Removed the old one, cleaned the reservoir of nastiness and vacuum bled all 4 corners. After the RR the pedal was super stiff, continued to the rest. Stiff pedal and great brakes afelterwards...

The seals on the master looked fine, pumped it manually and evacuated fluid. Possible it was clogged internally or at reservoir as it was full of sludge. I pushed a lot of crap fluid out and will be power bleeding and swapping all fluid.

How does everyone's antilock perform? I can lock the car up and gravel and don't feel much of anything abs wise. No light on either...

[jbontke]

How does everyone's antilock perform? I can lock the car up and gravel and don't feel much of anything abs wise. No light on either...

Does the ABS light have a bulb in it?

[e30vert]

For anyone who finds this post searching for the same issue here is am update.

Purchased a new brake master cylinder. Removed the old one, cleaned the reservoir of nastiness and vacuum bled all 4 corners. After the RR the pedal was super stiff, continued to the rest. Stiff pedal and great brakes afelterwards...

The seals on the master looked fine, pumped it manually and evacuated fluid. Possible it was clogged internally or at reservoir as it was full of sludge. I pushed a lot of crap fluid out and will be power bleeding and swapping all fluid.

How does everyone's antilock perform? I can lock the car up and gravel and don't feel much of anything abs wise. No light on either...

Makes perfect sense. Sludge is much more compressible than brake fluid. :LOL.

Good follow up for others with similar issues
ABS? Never engages for me and I hate it anyway. Vert see's excellent weather or its covered and hibernating.