Brake bleeding and other torments of the damned.

[jonathan909]

Back to my daughter's '03 Forester.  I won't get into all the painful details of what a horrorshow this has been to date.  Just trying to solve present problem:

Bleeding.

Since we weren't having any luck doing it Old School (stomp, twist, stomp, twist), I figured I'd give a power bleeder a shot.  Someone mentioned the Motive pressure bleeder here in an old thread, but looking around yielded mixed reviews that suggested they used to be great but in more recent years the quality fell off and everything leaked.  My local preferred source had the Performance Tool version:

https://wilmarllc.com/w89204/w89204-pneumatic-brake-bleed-kit

on the shelf and they have a painless refund policy, so it seemed worth a try.  The difference is rather than pushing fluid under pressure into the master cylinder, this one generates a vacuum from shop air and sucks at the wheel cylinder.

But on the first wheel (RR), we've already put 500ml of fluid through and the bubbles aren't letting up, leading me to believe that air is getting sucked through the threads of the bleed screw, as we have no reason to believe there are leaks anywhere else in the system.  I just learned that teflon tape is NFG for sealing in this application, as the brake fluid eats it.  Is there anything I can use to seal the threads and eliminate this (potential) leak during bleeding?  I realize, of course, that this is an intrinsic problem with a vacuum vs. pressure bleeder.

Helpful suggestions are, of course, welcome in addition to the actual answer.

 

 

 

[ronemus]

Use Speed Bleeders - just open, stomp as many times as necessary, then close.  I've used them on all my cars for over 20 years and they've worked flawlessly.  Easy and inexpensive.

[jonathan909]

They look like a Good Thing.  My only question is:  If you're stomping in the driver's seat, how are you to know when you've "stomp[ed] as many times as necessary"?

 

[czny]

13 hours ago, jonathan909 said:

They look like a Good Thing.  My only question is:  If you're stomping in the driver's seat, how are you to know when you've "stomp[ed] as many times as necessary"?

 

I've used something similar to bleed - a small hose with a check valve at the end. Far cheaper than vacuum bleeders etc.

They're called one man bleeders.

In my experience with Subaru master cylinders, it takes 6-8 pumps before you need to refill. 

Press the pedal slowly down, then slowly up so you don't draw more air back in. After closing bleeder, check your pedal for firmness or sponginess & sinking.

Rinse & repeat as needed until firm & holding well.

Edited October 17 by czny

[jonathan909]

I've decided that the Performance Tool bleeder I linked to at the outset is junk because sucking rather than blowing is inherently flawed.

In fact, here's what their product support person (who claimed that there are teflon tapes that resist brake fluid, but did not specify) said when I described the problem:

"These bleeders... suck at bleeding the system"

So I'll be returning it to Princess Auto today.  I'd try the Motive bleeder next (a jug with a hand pump that attaches to the master cylinder), but ran across this one:

https://speedibleed.com/

I like the idea of using shop air (or tire pressure - a cute hack) instead of a hand pump, it's cheaper than the Motive (which has no Canadian distributors - I'd have to buy it from Amazon), and comes from just over the border in BC.  Should be here in a day or two, will advise.

 

[czny]

Did you look up the ABS brake bleed procedure, IF that Forester has ABS?

https://www.subaruforester.org/threads/abs-pump-activation-bleeding-brakes.502561/

Edited October 17 by czny

[nvu]

Pressure bleeders are hit and miss as stated before.  It's the newer style reservoirs with a foam float in them.  They'll sometimes block the orifice and make things difficult.  I've had the motive one before,  More hassle than it's worth.  Especially cleaning it out after storage. Any remaining brake fluid you have will turn into brown gunk where black pump tube is, maybe it's the rubber bits.

I've had good results with a hand pump vacuum.  To get a good vacuum seal over the threads, I use thick grease and build a cone around the entire fitting.  Since mine is hand operated, I'd pump until there's enough vacuum, open and shut the valve, pump again.  The trick is to work the grease into the threads by getting a high vacuum with the bleeder closed, open slightly and close in small increments.  Once you're sure the grease has worked in, open just enough to get the fluid flowing while having moderate vacuum.  I just buy a big bottle of brake fluid, and slap it on top of the reservoir like a water jug.  It was a mityvac kit from 2000's, dunno if they're as good nowadays.

[jonathan909]

7 hours ago, czny said:

Did you look up the ABS brake bleed procedure, IF that Forester has ABS?

https://www.subaruforester.org/threads/abs-pump-activation-bleeding-brakes.502561/

Yes, it has ABS.  Haynes said something about using a scan tool to cycle the ABS, but mine doesn't appear to support that function.  If it's a simple matter of manually activating the ABS via a diag connector pin, that doesn't sound like a big deal - should be easy enough to track that down.

[jonathan909]

3 hours ago, nvu said:

Pressure bleeders are hit and miss as stated before.  It's the newer style reservoirs with a foam float in them.  They'll sometimes block the orifice and make things difficult.  I've had the motive one before,  More hassle than it's worth.  Especially cleaning it out after storage. Any remaining brake fluid you have will turn into brown gunk where black pump tube is, maybe it's the rubber bits.

I've had good results with a hand pump vacuum.  To get a good vacuum seal over the threads, I use thick grease and build a cone around the entire fitting.  Since mine is hand operated, I'd pump until there's enough vacuum, open and shut the valve, pump again.  The trick is to work the grease into the threads by getting a high vacuum with the bleeder closed, open slightly and close in small increments.  Once you're sure the grease has worked in, open just enough to get the fluid flowing while having moderate vacuum.  I just buy a big bottle of brake fluid, and slap it on top of the reservoir like a water jug.  It was a mityvac kit from 2000's, dunno if they're as good nowadays.

I've had a mityvac forever too, and I've got a vacuum pump (use it for AC evacuation and oiling), so there's no shortage here of potentially-useful kit.  Before returning the PT kit I tried putting some Dow Corning High Vacuum Grease on the bleeder threads, but even that didn't stop the bubbles - whether they're actually in the lines or occurring locally is a mystery only solved by abandoning the vacuum approach, so that's what I'm doing.  I'll have the Speedibleed kit on Monday and see how that goes.

[nvu]

Though if you're suspecting line leaks somewhere else, do a sanity check.  Engine off.  Keep pumping the brakes until they're rock hard and hold them.  Even if there was air previously, the pedal shouldn't drop after a minute.  It only drops if there's a leak.

[jonathan909]

That's what makes this so maddening - I do not suspect leaks elsewhere.  This all kicked off when the hill holder (apparently) malfunctioned and locked the brakes while on level ground, causing the car to be towed home - twice.  The hill holder is no longer in the car - I didn't just disconnect the clutch cable as suggested here, but yanked it altogether and joined the in/out brake lines together.  I have no reason to believe there are any leaks, and, as an aside, point out that I've only suffered one brake line failure (corrosion) in the decade+ that I've been driving and maintaining these things, and that was in the 1995 Legacy Wagon - almost ten years older than this car.

So my present sanity check is to push fluid until the bubbles go away.  If they fail to do so, I will declare myself insane.

[czny]

When you deleted the hill holder, did you use a 10x1.00 mm inverted flare union or a bubble flare one?

Flared ends on Subies are inverted flare, like Toyota.  You could be sucking air at the union(?)

[jonathan909]

2 hours ago, czny said:

When you deleted the hill holder, did you use a 10x1.00 mm inverted flare union or a bubble flare one?

Flared ends on Subies are inverted flare, like Toyota.  You could be sucking air at the union(?)

Hmmm.  Good point.  I may not have looked closely enough and it might be worth pulling it apart to confirm.

Though if it's sucking air, it stands to reason that it'd bleed fluid when we step on the brakes.

[czny]

20 minutes ago, jonathan909 said:

Hmmm.  Good point.  I may not have looked closely enough and it might be worth pulling it apart to confirm.

Though if it's sucking air, it stands to reason that it'd bleed fluid when we step on the brakes.

Sometimes, leaks are air only. Air molecules are smaller than brake fluid ones.

 

[jonathan909]

True, but I'm getting more than "molecular volumes" here - this isn't exactly a micron filtration situation...

 

[czny]

Dirt or brake dust between caliper piston and seal.

Small burrs on flared line ends(polish ends with fine scotchbrite in circular motion).

Rearmost master cyl piston seal sucking air thru vac booster.

Cracked line inside the unibody from a accident - a real stretch if this.

Bad crimp on flex line end. Damaged or missing copper washer at caliper banjo bolt.

That's all I got. Good luck and so long.

Edited October 20 by czny

[jonathan909]

None of the above.  Nothing so complicated, simply air getting past the bleeder screw threads.

We got our Speedi Bleed yesterday and bled the system today.  Quick.  Silent.  No pumping.  Painless.  No bubbles.  Just Works.

This is a great tool.  I don't think I've ever specifically endorsed any such here, but it gets a hearty two thumbs-up from me.