Gravity bleeding brakes

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I've usually let my indy shop handle brake fluid changes but the Accord will need front brakes in the coming future and I thought I'd DIY the fluid as well.

I've watched YT vids on the different ways to do this and I feel the most comfortable with gravity bleeding. I know it takes some time, but it doesn't need special equipment and seems to work very well. I don't want to do a traditional pedal bleed and possibly damage the 16 yr old master cylinder. Here are my questions about GB:

- Does the MC cap need to be open or closed during the process?
- Can I crack open all 4 bleeders at once?
- Besides being less messy, is it necessary to fit a tube over the bleeders, or I can I just let them drip bare?
- Do I have to pump up the brakes before cracking the bleeders?
- Do I have to touch the pedal at all during the process?

Any tips you guys can offer will be very appreciated. Thank you!
 
Waste of time imo. Makes bleeding the brakes a real chore.

Gravity: safe but SLOW
two-man: high potential for damage without an experienced foot.

Vacuum is the safest. Might not be perfect but you can always vacuum the junk out and then use another method for the finishing touches.

Power bleeding is the best but not everyone bleeds enough brakes to own one. A vacuum extractor is much more versatile and makes sense for a DIYer to own.

EDIT: Cap open, I am curious if cracking all four at once is better than a single circuit at a time? Just pull the cap, crack the bleeder(s) and let it drip if you want. A hose on the bleeder makes the progress visible. I wouldn't really want brake fluid dripping everywhere, I'm pretty sure I have brake fluid spots on my car from being clumsy with a hose or my hands.
 
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Here your go: https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4242884/1




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I've done it several times with good results. I remove brake fluid from the MC, being sure not to suck out too much and allow air into the brake lines, fill it to the top with fresh fluid and cap it. I do the rear wheels first, keeping an eye on the MC and topping up as needed. When done with the rear, tighten up the bleeders put on the wheels and move to the front. I don't touch the brake petal. You can put a hose on the bleeders, I do that and put a large oil catch pan under the rotor. The hoses are cut long enough to clear the rotors and hang about an inch above the catch pan, I bottle it to give an idea of how much each caliper drained. The flow can be controlled via loosening or tightening the bleeder. Mine don't drain very fast. The job can be done with about a quart or so of brake fluid. I usually buy three quarts and do both my Jeeps on the same day.
 
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I've only ever gravity bled one wheel at once. I do use a short length of tube into a jar just to keep things clean although there is no need for the tube to be submerged in fluid. If you don't bleed into a jar you have no indication of how much fluid has been bled on that wheel. I keep the cap off the reservoir because you need to keep an eye on it and top it up. Don't touch the pedal at all, You will find a big difference between the flow rate between front and rear wheels with the rears taking much longer. Other extreme is gravity bleeding on the front brake of a motorcycle which is very quick. Low viscosity Dot 4 bleeds faster than the regular type.
 
Its going to be a small chore getting to all bleeders without removing the wheels. Unless your fluid is contaminated or cooked i would just do the turkey baster method and swap out 3/4 of the fluid a couple or few times.
 
You get many different procedures so I'll add mine which is a little faster than gravity.

- Start with the farthest wheel and I use a Mityvac vacuum system.
- Remove the MC cover then use a turkey baster and remove some fluid but do not empty and introduce air into the system.
- Remove the wheel, connect the hose to the bleeder then loosen bleeder.
- Pump several times (make sure valve on Mityvac is on vacuum not pressure (can act as a pump on some models).
- Check MC and make sure to keep topped off with fresh brake fluid. Make sure you use fluid your vehicle specifies.
- Pump until fluid is clear and keep MC topped off.
- Go to the next farthest and repeat.
- Check the FSM as you may have to bleed the ABS as well.
- Rinse any spilled fluid on paint with water as it will eat paint.
 
How are you going to hurt the MC by doing a 2 person bleed? Is it because the MC stroke is longer than normal so the seals might catch on some lip in the bore?

I've never once ruined a MC by doing a two person bleed, even on old cars. The only time I've had an issue is when the car comes in with a blown component that caused complete fluid loss. Master's don't like being run dry, but as long as you keep the fluid full I don't see the issue.
 
Originally Posted by 14Accent
How are you going to hurt the MC by doing a 2 person bleed? Is it because the MC stroke is longer than normal so the seals might catch on some lip in the bore?

I guess... I've heard this about my Honda, so I put a chunk of 2x4 under the pedal to limit the stroke. It still bleeds just fine.

Also, I don't feel snookered by buying, and using, a Mity-Vac. It was all of $35, and I've already used it for more things than I count. Brake bleeding is just one thing. Yes, I use it along with a partner pushing on the brake pedal. The vacuum part just helps make sure I don't drip or leak.

That A1Auto video... pretty good, but I always use a box end wrench on the nipple. Rust belt and all that. A 12 point box end has always been OK here, but the one time I used an open end wrench (was in a hurry) I immediately rounded it off.
 
For me, there is a difference between flushing, or renewing fluid and bleeding.
I renew the front brakes fluid with a simple pumping with hose immersed in fluid method.
1st I drain most of the fluid outta the master, then do the driver side, then the passenger side.

I do not renew the rears nearly as often.

Bleeding is to remove air, so that is a different story.
All good.
 
$40 Mighty Vac or off brand vac will work quicker. I've done gravity, too. Jack stands, crack all 4 bleeders with trays under, stand by reservoir to keep topped up, in about 10-15 minutes fluid will be pretty clear out of bleeders. This was on a Civic, not sure if your Mazda will be similar. Remember, there will probably still be old fluid in ABS parts if you don't have a tool to cycle the ABS.
 
As mentioned above, you need to see when the fluid runs clear, so I use the small plastic bleeder jar rather than let it drip. I only do one wheel at a time also. Farthest first working to nearest. MC cap off. It takes a while but it is fun and easy. Doing all 4 wheels at once I would worry about the flow being so low that air could enter.
 
Originally Posted by Tones
Doing all 4 wheels at once I would worry about the flow being so low that air could enter.


This is not possible. The reservoir above the master cylinder will ALWAYS be higher than the calipers. Even if the flow-rate seems low, there is zero chance of a static brake system ingesting air at the caliper vent port, using the gravity-bleed method.
 
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