I tried to bleed my brakes...and f***ed it up

"marshknute" (marshknute) 08/09/2015 at 19:24 • Filed to: None

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So a friend and I changed the pads on my WRX (successfully) and tried to bleed the brakes. The result: 6-inches of spongy pedal travel.

I’ve been trying to figure out what I did wrong. I found two mistakes that probably caused the problem. Let me know if my diagnosis sounds correct because I want to be able to do it properly in the future.

First Mistake: we bled them in the wrong order. We worked from front right and worked counterclockwise. Granted, we only bled the brakes rather than completely flush the system, but it still isn’t the correct way to do it. I don’t think this was the main problem considering my friend has never had an issue bleeding his brakes out of order. I think the second mistake was the real culprit:

Second Mistake: we let air get into the brake lines. We loosened the bolt to let the brake fluid drip out, slowly pressed/released the brake pedal twice, and then tightened the bolt again once it stopped dripping.

In hindsight, we should have started pressing the brake pedal first , and then loosen the bolt. Let the fluid drain, and tighten the bolt again before releasing the brake. By keeping the bolt open the whole time, we probably just sucked air into the brake lines every time we released the brake pedal.

Btw, my friend has always used a pressurized brake bleeder for his Ram, Cayman, and Z06, and has never bled brakes without using one. Now that I think about it, the technique we used on my WRX probably would be acceptable if we had used a pressurized brake bleeder, since it prevents air from getting sucked into the brake lines.

And since I commute into NYC on weekdays, I had to drop the car at a garage so they can fix it (and borrow my dad’s Tundra in the meantime). Not a great start for someone who has never wrenched before and is now extremely hesitant to ever try it again.

1111111111111111111111 > marshknute 08/09/2015 at 19:30

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Bummer, but lesson learned.

bob and john > marshknute 08/09/2015 at 19:31

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for having never wrenched before, I dont know if I would have recommended a brake bleed to be your first thing...it relatively easy to screw up and pretty dangerous when you do.

4muddyfeet - bare knuckle with an EZ30 > marshknute 08/09/2015 at 19:32

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Trying is the only you’ll learn, and it looks like you’ve learnt a lot! On your first go: No harm done to the car, a small dent in your wallet, and a favour owed to your dad. It could be a lot worse, so keep on keeping on.

MM54 > marshknute 08/09/2015 at 19:33

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You are correct on where you went wrong - that method will work, however, with a set of speed bleeders (which are basically bleeders with check valves in them), which can be had for a couple bucks a pair. I’ve used vacuum bleeders and I’ve used speed bleeders, and I prefer the speed bleeders (they’re cheaper too).

In general you want to pump the brakes to build pressure and hold them while a helper cracks the bleeder, then once the pedal is almost down the whole way (you shouldn’t go 100% travel) close the bleeder, and repeat.

DoYouEvenShift > marshknute 08/09/2015 at 19:34

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Haha! You pretty much figured out what you did wrong. But dont hesitate to wrench again. Knowing what and how you fucked up shows you have an analytical mindset. So please don’t get discouraged, at least youll know what not to do.

If it makes you feel better, Im a Master Tech, and I still mess things up everyonce in while.

Mmmmm > marshknute 08/09/2015 at 19:40

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Sounds like your problem, also just always make sure to keep an eye on the master cylinder. Running out of fluid in there is another easy way to get air into the system.

VincentMalamute-Kim > marshknute 08/09/2015 at 19:44

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You screwed up but you figured out why. You had the courage to try. Like everyone says maybe a brake bleed wouldn’t have been the first wrenching to do. Brakes are easy to work on, pads, rotors but bleeding is a technique.

I disagree that screwing up the bleeding is dangerous. Because you know you screwed it up when the brake pedals goes to the floor. Now if you went driving around on the freeway in that condition, that is the definition of dangerous. But you didn’t because you were smart.

This is a great way to learn. Keep at it!

I always use my Motive pressurized brake bleeder because repeatededly pressing the pedal is a pain and I don’t have any friends to press the pedal.

OTOH, I have a friend that is trying to install a hitch. I told him it will be easy - 4 bolts. But he emailed me “Where do I jack up the car?”. Next email was please install the hitch for him. No. What was the issue? “The car fell off the jack.” I sent him very clear step by step instructions. After thinking about it gain, I told him “This is too dangerous for you. Just bring it over and I’ll do it.” But you have the mechanical smarts that he doesn’t.

marshknute > MM54 08/09/2015 at 19:46

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In that case, I’m definitely investing in some speed bleeders.

And what’s the reason behind not going to 100% pedal travel? Is that so you lock up (activate ABS) before you reach the floor?

Demon-Xanth knows how to operate a street. > marshknute 08/09/2015 at 19:49

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Protects the seals in the master cylinder.

Arch Duke Maxyenko, Shit Talk Extraordinaire > marshknute 08/09/2015 at 19:53

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Get a power bleeder, and the right adapter for your car. It’s well worth the effort and makes changing the fluid a breeze. Also remember to start with the furthest wheel first (back right) then the next furthest and so on until you’re at the front left. And if your clutch shares a reservoir with your brakes, get an extra liter to bleed that, too.

CCC (formerly CyclistCarCoexist) > marshknute 08/09/2015 at 20:01

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I've bled bike brakes before, but bleeding car brakes is another thing. Good job for making the effort to do it. :)

JQJ213- Now With An Extra Cylinder! > marshknute 08/09/2015 at 20:11

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Let me just say.. You are a risk taker for tackling that as a first assignment!

OPPOsaurus WRX > marshknute 08/09/2015 at 20:26

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Well fucking wonderful. This instills tons of confidence in me as I prepare to bleed and replace my wife’s brake fluid

MuchWagon > marshknute 08/09/2015 at 20:28

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primary mistake: driving commute to NYC! I’m assuming a regular 9to5 tho... No transit anywhere?

Berang > marshknute 08/09/2015 at 20:32

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The bleed order only really matters if you’re doing a complete flush of the system since you’re trying to flush out all the air and fluid, not just squeeze old fluid out of the wheel cylinders.

The real issue was letting air into the line by letting off the pedal with the bleeder screw open.

marshknute > MuchWagon 08/09/2015 at 20:40

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No, I do take the train, but I need some way of getting to/from the train station. The real problem is not having any tools myself being a recent college grad. My friend brought his tools, but we can’t do repair after work b/c it’s dark.

marshknute > OPPOsaurus WRX 08/09/2015 at 20:42

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Well please learn from my mistakes! Honestly, I’m somewhat glad it didn’t go well b/c I now have a better understanding of how the system works and what I need to do instead.

OPPOsaurus WRX > marshknute 08/09/2015 at 20:44

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Lo is good to try. I had no idea what i was doing with half of my last repair.

415s30 W123TSXWaggoIIIIIIo ( •_•))°) > marshknute 08/09/2015 at 21:38

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I have triple webers on my Z and I fucked them up today, I tried to work out an issue I had and I ended up fucking it all up. Now I have to have a friend come and dial them in..... shame....

orcim > OPPOsaurus WRX 08/10/2015 at 04:29

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Don’t feel bad - it’s the way it always is until you do it at least once. I just dropped the head off a Previa onto my body and a few valve covers hit the ground - it wasn’t supposed to drop and I hadn’t marked them yet for the pull. Gads do I feel dumb. (Especially calling “help” from under the car and no one around to hear.)

You can tell a Finn but you can't tell him much > marshknute 08/10/2015 at 11:18

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Subaru’s (at least the STi and I’m guessing WRX) have a weird order for bleeding brakes. They have a crossover brake system, so you don’t actually start at the far corner and work your way closer. The recommended order from Subaru is:

Subaru Recommends:
1) Passenger Front
2) Driver Rear
3) Driver Front
4) Passenger Rear

I’ve done mine once and used the Motive Power Bleeder. It’s definitely handy and allows you to do it by yourself as you don’t need someone pressing the brake pedal for you. I don’t think doing them out of order would be that big of a problem.

As for getting air in the lines, you definitely did that. When bleeding brakes if you are doing it the old fashioned way you definitely need to tighten the bleeder valve before the person stepping on the brake pedal lets off the brakes.

Bleeder catch bottles are a good way to go. When using them, hang them above the caliper, that way the air bubbles are always going up. Whether you are using bottles or just dumping from the bleeder tube to a catch pan, make sure the bleeder tube is going well above the caliper before it turns to dump the old brake fluid.