Brakes don't seem to want to bleed

This is getting really frustrating.

I can't seem to get the air completely out of my brake system. What's really annoying is having to hand the truck to someone else for the ABS pump bleeding procedure.

I have decent braking for about two days after bleeding, and then they go right back to shit. I can get fairly normal action if I give the pedal one or two "pre-pumps," pushing the pedal once or twice quickly before then braking like normal. If I don't do the "pre-pump," the pedal goes about halfway down before finally grabbing softly.

Manual bleeding doesn't seem to do much, no matter my technique (some work better than others). I really only see (feel) results when I have a shop hook up the computer and run the ABS pump. But two days later, it's back to Square One.

This has been a somewhat ongoing thing with my truck. This is about the fourth or fifth time it's done it, but this is the longest I've had it not be resolved.

And here's the kicker. I haven't opened up the lines in months, one might even say a year (except to bleed them AFTER the problem already surfaced).


Is there anything I'm missing? Any weird quirk to get the air out? Any long-term resolution so I don't have this BS come back *AGAIN*?


DCLB Sport non-ATRAC (ABS pump on the passenger wheel well). Steel extended brake lines (DOT numbers......the pricey ones). Porterfield R4S compound. Otherwise all stock components.

 

Sounds like a fitting is a little loose somewhere and letting air in. I would get under and look at each wheel while someone else pushes the brakes to see if you can find a small leak. Work inboard from there.

 

Yeah, but nothing is wet. If there's something loose enough to let in air, it would be loose enough to be wet where it's leaking.

 

Yes, you're correct. Have you been keeping track of the brake fluid level?

Another idea: have you done a full drain/ replenish of the brake fluid? You could have water in the fluid. It would act just like this.

 

No fluid loss, even over a long time.
Fluid gets flushed between 150% and 200% every year for that exact reason (I can feel when it's getting saturated).
Currently it's doing it again, and the fluid was flushed by a shop last Monday, after I flushed it a week earlier. All the flushing is due to trying to bleed the damn air out. So right now, there's not a drop of old fluid in there.

Using ATE 200 fluid, this is getting pricier than I'd like!

 

Check the adjustment of your rear shoes, and check your front wheel bearings for play.

 

Wheel bearings are about two weeks old. Ditto for rear shoes. Adjustment done before all this bleeding BS.

 

Questions.

When you bleed the system are you getting air bubbles?

Bleed starting at the furthest wheel and working back towards the closest wheel.

Big question was the rear wheel adjustment done correctly?

(Tighten the brake adjuster until the wheel locks and back off 15 notches on the star adjuster on both rear wheels.)

If so and you do get all the air out when you bleed, you do have a leak somewhere. It may be very small as it takes two days of driving to show its ugly head.

 

You torque those front axle nuts correctly? Did the brake issue begin before the other repairs were done, at the same time, or after?

 

Supposedly need to hookup a computer to do a proper bleed.

Never done it. But maybe look into that.

 

https://www.youtube.com/watch?v=K-6g9IXmvNE

 

175ft# (I wrote the spec on the inside of the dust cap a while back). So yep, torqued 100%.
I've had this issue on and off for years. Seems like any time I look at the brakes with a sideways glance, or if I sneeze near them, they get spooked and get the hiccups.

Yeah, it's the need for a computer that's pissing me off. Because I like doing 110% of everything myself, and bleeding the ABS pump *requires* me to take it to someone. Did it last Monday, and I'm sure they'll be real happy to see me again.

 

I'd double check things with your rear shoe's adjustment, be sure the wheel cylinders aren't leaking even the slightest (pull the rubber boots back a bit to ensure there is NO wetness), and double check that there is no wetness anywhere in the whole system. If all OK, replace your master cylinder, and be sure to bench bleed it before installation.

 

How did you make out with this problem ?

 

Lots of time on the stealership bleeder machine.