Bleeding ABS Brakes

[Dennis Smink]

I was going to do a brake job on my 2001 Ranger (4WD). I had planned on changing the rotors because I believe these are the original rotors (152,000 miles). While reading the forums, I noticed Richard L. said the bleeder valve should be opened so old dirty brake fluid doesn't get pushed into the system when you compress calipers.



I have 2 questions.



1. If I bleed the brakes after the job, would I still have to open the bleeder valve while I compress the caliper?

2. Is there a special procedure to bleeding ABS brakes VS regular? I have never bled brakes but I thought when ABS first became popular, that there was a special procedure.

 

[EddieS'04]

Yes compress the caliper with bleeder open.



Yes open bleeders when bleeding. Start with right rear, left rear, right front, left front. Bleeding is the same with abs.



Be sure to watch the fluid level while bleeding. I do 3 bleeds per wheel if air is out. Then I top off the master cylinder after 3 per wheel.

 

[Richard L]

Dennis,

Good question.



When you change brake pads, you will normally be required to push the pistons back into the calipers to fit the new thicker brake pads between the calipers and the rotor.



By opening the bleeder valve before you push the pistons back into the caliper you will expell the old contaminated fluid out through the bleeder valve and not back up into the ABS system.



There is no different procedure for bleeding ABS brakes than conventional brakes. It is just not recommended that you push the pistons back in and let that old contaminated fluid to back up into the ABS unit. The contaminates can mess up the unit and that can cost some big $$$. That's why I never recommend using auto bleeders that push the new fluid back up through the system from the wheel to the master cylinder. You always want the fluid moving down since any moisture that contaminates the fluid will collect at the lowest part of the brake system which is the caliper or wheel cylinders. (water is heavier than oil)



The normal procedure is to just start at the wheel furthest from the Master Cylinder and wheel by wheel, move closer towards the master cylinder. That typically means to bleed the right-rear first, followed by the left-rear, then the right-front, and finally the left-front. This orientation is if you were sitting in the drivers seat.



The procedure I suggest is to bleed each brake with a hose from the bleed valve to a glass jar. This allows you to see the color of the fluid as it exits the bleeder valve. Contine to bleed each wheel until the fluid comes out clear. (you may have to dump the jar of the old fluid so you can see when clear fluid is coming out. Be sure to continuously monitor the fluid in the master cylinder to insure it never runs out of fluid or you may have to start all over and bleed the air out of the master cylinder.



This procedure should be done with every brake job or every 2-3 years, whichever comes first.



...Rich

 

[Gavin Allan]

I bled my motorcycle's brakes and clutch while changing out the fluid with a vacuum pump. Worked very easy and did a great job with no mess.

 

[Igor Smetaniuk]

I lightly squeeze the rubber brake hose with a small needle-nosed lock-grip pliers - just enough to cut off flow from master cylinder and not damage the hose. I've been dion' this since I was a kid and never damaged a brake hose.



I then remove the bleeder completely, turn brake caliper upside-down while out of the mounting bracket and let all of the old crap drain out for a while. Then I take a large syringe and fill the caliper with new fluid just as a flush to drain a second time. This helps get that old moisture laden dirty residual out nicely. Then I fill immediately with new fluid and install bleeder to closed position so no moisture is absorbed by the new fluid. I always buy the smaller containers of brake fluid so I don't have much left over. I never keep left over fluid. I'm just anal about moisture absorption unless you could vacuum seal the left over fluid.



When the caliper is back together with pads & rotor, I take the grip pliers off the brake hose to commence the perfect bleed. I place a wrench on the bleeder and then slip on my 6 foot piece of 3/16" clear rubber tubing over the tip of bleeder (it should fit snugly) or you can always hold it while cracking the bleeder. I run the tubing up over my side mirror (or cargo hook for rears) and let it drop back down to a catch container. When I crack the bleeder, you can watch the dirty fluid and air bubbles from the brake lines work their way up toward the mirror followed by a stream of nice clean fluid and no bubbles after 3-5 bleed rounds. It's amusing each time I do it to this day and makes it fun to see a job well done.

 

[Richard L]

toptobottom,

That's more work than simply opening the bleed valve and pushing the pistons back in by hand which pushes the old fluid out. Follow that with bleeding your brakes until the fluid runs clean.



I prefer to push the piston back in by hand since I can feel any binding or grating which would indicated that the caliper bore is pitted and probably needs to be rebuilt or replaced.



...Rich

 

[Igor Smetaniuk]

+1 on pushing in piston by hand.



I wish they had rebuild parts available for mine. I miss the days of having my 2nd rebuild set waiting to change out with each brake service.

 

[Richard L]

toptobottom,

I usually buy rebuilt calipers for every brake job, and have been doing that for many years.



I found that you can buy rebuilt calipers very inexpensively at most auto part stores. Most will give you a 50K mile warranty, and many now offer a lifetime warranty. I normally need new pads between 40K and 50K miles and I simply take to old rebuilt calipers back to the store with the receipt and exchange them for new rebuilt calipers under the warranty. Life time warranty allows you to keep bringing them back.



I rebuilt my last set of calipers back in about 1987 and now I only use rebuilt calipers and I have never gotten a bad rebuilt caliper.



...Rich

 

[EddieS'04]

I lightly squeeze the rubber brake hose with a small needle-nosed lock-grip pliers - just enough to cut off flow from master cylinder and not damage the hose. I've been dion' this since I was a kid and never damaged a brake hose.

Then you have been darn lucky. The hose is a multi-layer design. The high pressure inner gets damaged and the outer, wont hold the pressure. Or the inner damage blocks the pressure. there is a very good reason that you never hang a caliper by the hose.



I dont know or heard of any mechanic do this. In my over 40yrs of being a gearhead. I would never do it.



Sounds like something from the 1920's, before I was born.........Sorry just my take on brake safety.