Don't push back brake fluid into the ABS when changing pads?

Status
Not open for further replies.
Joined
Mar 24, 2008
Messages
874
Location
A Warm place to live in
I've read in a BITOG post you should never push back the brake fluid into the ABS when pushing the pistons back into the caliper when changing disc brake pads. Instead it is advised to open the bleeders and let the returning brake fluid leak out. Is this a valid idea? I have never opened the bleeders when I changed brake pads; I just push the pistons back and let the fluid reenter the master cylinder. And I never had anything bad happen thereafter.
 
Never had anything bad by compressing the pistons back. Ford, Mercury, Jeep, Toyota - other brands may be different but on these I've had no issues whatsoever.

IMO brake hydraulicss are designed for fluid to move both ways, so as long as there's no sudden pressure surge away from the calipers it should be fine.
 
I've been cracking the bleeders when I press the caliper pistons back in with ABS/ESP. No sense in forcing dirty fluid through the system. I then gravity bleed or hook up the Motive Bleeder to bleed the caliper as a CYA.
 
I usually don't worry about it, but that being said, my fluid is generally fairly clean. If it were a 10 year old car that had never been serviced, I might do it differently, IE bleed fresh fluid down to the calipers and THEN push the pistons back to change the pads.
 
Your not pushing fluid into the ABS system, or pump, just back into the master cylinder. The theory is that some dirt or debris in the old fluid will get trapped under the flapper return seal for the master reservoir and greatly reduce the effective line pressure of the master cylinder by pushing fluid past the flapper/check valve and out the high pressure hydraulic lines at the same time when you apply the brakes.

As nthach said, always crack the bleeders and push out fluid to compress pistons, all you have to do is use a piece of hose like fish tank air line works great, put it over the nipple, loop the hose in 360 loop and into a small empty water bottle. You can watch as you push fluid and compress piston, no air will come back into the caliper because of the loop. No need for bleeding unless you want to change out the brake fluid which many don't do often enough!
 
I believe this very thing myself. However, there seem to be two schools of thought on this. Those who believe the same and others who say they've never had problems doing so. I'm in the first camp.
 
Before you do a brake job. The smart way to do it is suck all the old brake fluid out of the master, put new fluid in. Bleed your brakes. And IF you have a say Foxwell ABS scan tool do the ABS bleed. Then do the brake job and push the cleanest you can get fluid back into the master.
 
My first ever pad change on an ABS car (2000 Cavalier) I pushed the fluid back up. A few days later, the ABS light came on. May have just been a coincidence, but since then I always open the bleeder valve and then do a quick bleed after. No problems since.
 
I like to bleed the fluid at each wheel....For me, .the fluid has always gotten dirty at the wheel...
In a shop, time is money.
It is FASTER to pull some fluid out of the master cylinder and skip bleeding at each wheel.
It also avoids issues with bleeder screws.
If they can get you in and out faster, they can get more jobs done per service technician.
You and I.......a few extra minutes to bleed at each wheel is no big deal, and we are satisfied that we did a slightly better job in the process.
 
Status
Not open for further replies.
Back
Top