WTF is going on with my brakes? (Subaru content)

Working on my cursed 2003 Subaru Baja. It started leaking from three brake lines last week simultaneously. One was one of the (2) feed lines from the master cylinder to the electronic brake control module (EBCM), one was from the EBCM to the LF caliper, and the last was from the EBCM to the RF caliper. We ended up replacing the entire line from the EBCM to the RF caliper, because that one was short and routed pretty simply. We patched the other two lines in good sections, simply because the routing is somewhat satanic. We had all the brake lines detached from the EBCM at some point, trying to get things routed.

Got it all buttoned up last night and went to bleed the brakes and some seriously strange stuff started going on. RR brake bled normally, and the car started building a brake pedal. Move to the LR caliper, and you can take the bleeder all the way out and nothing comes out of the caliper, not air, not fluid, nothing. Brake pedal doesn't sink down either, when you open the bleeder. Okay, strange. Same thing at the RF and LF calipers. The vehicle builds a brake pedal like normal if you pump the pedal, but the 3 brakes do not apply at all. Cracking the lines, we have fluid getting to the EBCM from the master cylinder.

Do these require some sort of automated bleed procedure from a Subaru scan tool? I did see some references to it, but everyone was saying that their car, they bled the brakes for days and were getting fluid out of the calipers but it never built a brake pedal. Mines the complete opposite.

Help. I really hate this car.

Did you pressure bleed? My suspicion is that you need to activate the ABS via the scan tool, but pressure bleeding might help I suppose. If you had more stopping power I'd say go out on an empty road and activate the ABS with some hard stops, but that's probably a bad idea with one rear caliper functioning.

The springing of three simultaneous leaks suggests there's something else going on, perhaps pressure being retained rather than released. Have you checked to make sure the rubber lines haven't swollen internally?

I have personally witnessed (and had to bypass) an ABS valve body locking up- no fluid in, no fluid out.  It was one of those things I would have thought of as an internet myth if I hadn't encountered it in all of its' real world, "it's negative berkeley out here and the brakes are locked solid what is my life?" glory.

02Pilot said:

Did you pressure bleed? My suspicion is that you need to activate the ABS via the scan tool, but pressure bleeding might help I suppose. If you had more stopping power I'd say go out on an empty road and activate the ABS with some hard stops, but that's probably a bad idea with one rear caliper functioning.

The springing of three simultaneous leaks suggests there's something else going on, perhaps pressure being retained rather than released. Have you checked to make sure the rubber lines haven't swollen internally?

The three leaks were because they were all running through one of those plastic clips that holds dirt and stuff against the lines, and thanks to lovely NY road salt they all rotted out. Maybe one of them was leaking and making the others leak, but they were all so crusty, we knew that they weren't long from leaking, and by the time we fiddled around with the line that definitely was leaking, they would be. 

Yeah, I'm not crazy enough to try and do ABS stops with only one rear brake. Although if I totalled it in the process, I'd be rid of this wretched car.

How long since the fluid had been changed? If it's old, there's a bunch of water in it - if that's the case I wouldn't be surprised if the ABS pump is locked up with rust.

It shouldn't be, but make sure the hole in the caliper isn't plugged- Pull the bleeder screw right out, and push a pick through into the piston bore.

Try gravity bleeding.  If you have a ton of air in the lines, which you obviously do, it is very hard to build any kind of pressure at all.  Start by cracking the lines at the master until you get clean fluid, then crack them at the inlet oto the abs, then crack at the outlet, and so on.  Don't bother pumping the pedal.  If you get no significant amount of fluid out the line, see paragraph 3.

Did the master cylinder piston stick down in the bore?  You said you bled one, and the rest won't go.  If you pushed the brake pedal down farther than its normal travel, you might have run the piston down into some rusty junk in the bore, and its not coming back far enough to uncover the transfer port.  With power brakes, you won't be able to feel this, but you can probably unbolt the master from the booster and pull it far enough away to see if its returned all the way.

Streetwiseguy said:

It shouldn't be, but make sure the hole in the caliper isn't plugged- Pull the bleeder screw right out, and push a pick through into the piston bore.

Try gravity bleeding.  If you have a ton of air in the lines, which you obviously do, it is very hard to build any kind of pressure at all.  Start by cracking the lines at the master until you get clean fluid, then crack them at the inlet oto the abs, then crack at the outlet, and so on.  Don't bother pumping the pedal.  If you get no significant amount of fluid out the line, see paragraph 3.

Did the master cylinder piston stick down in the bore?  You said you bled one, and the rest won't go.  If you pushed the brake pedal down farther than its normal travel, you might have run the piston down into some rusty junk in the bore, and its not coming back far enough to uncover the transfer port.  With power brakes, you won't be able to feel this, but you can probably unbolt the master from the booster and pull it far enough away to see if its returned all the way.

I know the calipers aren't plugged, because I bled them at my work before discovering the leaking lines (They weren't full-out blown,. I just had a pedal that slowly sank and thought maybe I had air in a caliper or some such) and they bled fine.

We tried using one of the handheld suction pumps on it, but had no luck. 

I know (or at least strongly believe) the master cylinder is okay, because if we crack the feed lines from the master to the EBCM, the pedal sinks normally and we get fluid at the fittings there.

The ABS did still work on this car before attempting the repair, because we had some really greasy snow the week before and the ABS activated and worked fine then

I was curious about your problem so I did a bit of searching, it seems like you can activate the ABS module through the diagnostic port by grounding a couple of pins - https://www.iwsti.com/forums/gd-general/95155-im-stumped-brake-problems.html but which pins may depend on your specific year. Check out http://jdmfsm.info/Auto/Japan/Subaru/ for a bunch of service manuals (if you go up in the parent directory there are other manufacturers as well), the baja section is lacking but the legacy/outback section should have your answer. On page 2778 of the 03my_legacy-eu.pdf it details the procedure to activate the pump and that is where I would start. Under the 04 baja section there is a really good description of how the ABS system functions.

I had an 04 Legacy and I'd pull the ABS fuse over the winter as I hated how the system performed on the half wet asphalt, half slush/ice I was always driving on but it worked decently through the rest of the year when all 4 tires had the same grip levels.

Good luck,

Adam

the ABS valve is a pass-through device when the ABS is not actively controlling brake fluid pressure.  should have no effect on current bleed situation.  i recommend pressure bleeding with a low pressure applied to reservoir, 10 PSI is plenty.  do this with one bleeder from each brake circuit open simultaneously.  it's a diagonal split system, so i would open both rears, and let it flow until clean fluid comes from both bleeders.  then i'd close those and do both fronts simultaneously.  i don't know the exact hardware details of your system, but sometimes the "bleeding with both circuits open" works because some systems have a shuttle valve in them that physically moves to block off a circuit that has a leak.  those devices need to see equal pressure on both sides to reset.

Gravity bleeding works well if you are not impatient.  A better way is a pressure bleed.  Get a used cap for the master, drill a hole for an air chuck, attach the air chuck (and seal it), hook up an airline (limit to 5-7 psi) and go around loosening each bleeder screw. I had to do this with my Duramax (completely rusty brake lines) and it would not gravity bleed.  That truck has a notorious ABS system.  The pressure bleed worked first time and so well that bleeding with the scan tool was an afterthought.

I had this same problem with an older BMW. Manually cycling the ABS pump (after some percussive maintenance) fixed it right away. 

Well, gents, let it not be said that I'm too proud to admit when I screwed up. Had the patch lines to the left front caliper and the middle feed line to the EBCM swapped, causing some strange fluid lock condition. Swapped the two and all is good. D'oh

At least it followed the rule of "if it worked fine and then suddenly didn't work, the problem is likely something simple"