Anti-lock brake service

[Flivver250]

Set me straight on depressing the pistons back into the caliper on an anti-lock brake system. I was told you should open the bleeder when squeezing the piston back in or you could risk faults or sensor errors in the system. Naturally I have always just squeezed the pistons back in regular braking systems and have done the same to anti-lock without any harm detected. I have only had to change pads in anti-lock a couple times. So, do you open the bleeder or is that an automotive urban myth?

 

[dlcwent]

Let the experts tell me I'm wrong but I've never opened a bleeder when pushing the pistons back in. And our shop does hundreds of brake jobs a year. Never had any problems. So I say urban myth. JMO

 

[houdni]

Bleeder is only there to remove pockets of air should you have a component removed/repaired... Leave the bleeder screw closed

 

[theoldwizard1]

Set me straight on depressing the pistons back into the caliper on an anti-lock brake system. I was told you should open the bleeder when squeezing the piston back in or you could risk faults or sensor errors in the system. Naturally I have always just squeezed the pistons back in regular braking systems and have done the same to anti-lock without any harm detected.

I have done it both ways, with no issues.

EricTheCarGuy (on YouTube) is a big proponent of pinching the brake line and opening the bleeder before pushing the piston back in, just because it get some of the old fluid out of the system.

 

[lametec]

I've always just pushed 'em back in, and never had a problem.

With that said, though, there's no harm in opening the bleeder and letting some fluid out. Just refill when done.

 

[bwringer]

The theory is that if there's any gunk or whatever in the system it would be in the calipers, so you don't want to push that back into the ABS parts.

The odds of causing a failure in a normally functioning system if you skip this and just install the pads normally are very, very low.

But the odds of snapping off a bleeder screw get pretty high after a couple of years.

Picture the average four or five year old car that rolls up for its first set of brake pads. Here in Indiana, you're going to be VERY lucky if you can even get one or two of the bleeder screws open.

 

[Ponchoguy]

Set me straight on depressing the pistons back into the caliper on an anti-lock brake system. I was told you should open the bleeder when squeezing the piston back in or you could risk faults or sensor errors in the system. Naturally I have always just squeezed the pistons back in regular braking systems and have done the same to anti-lock without any harm detected. I have only had to change pads in anti-lock a couple times. So, do you open the bleeder or is that an automotive urban myth?

I don't touch the bleeder unless there is an issue (hydraulic leak, part needs replacing, it snapped off, etc).

 

[TNToy]

I've worked in dealerships and fleet shops for 15+ years, and I've never seen someone open a bleeder for that reason.

I've done it by clamping the line and pushing the old fluid out of the bleeder if I was doing a redneck brake flush at home, but that's about it.

 

[nh_yota]

I think the chances of snapping off a bleeder screw are far higher than damage resulting from pushing the brake fluid backwards.

 

[joe_padavano]

The only reason to open a bleeder is to get air or old fluid out of the line, period. I've never had an issue simply pushing the pistons back in on my ABS vehicles. There is some merit to flushing the system with clean fluid every few years, however.

I am deathly afraid of squeezing brake hoses with a clamp, however. That was driven home to me in auto shop back in the 1970s. I think that is a half-@$$ed technique.

 

[bwringer]

It's been a while since I bought a new-ish car, but if you actually look at the factory maintenance recommendations (not the work of fiction the dealer pushes), you're supposed to flush the brake fluid every so often. I think on my Toyota it was every four years.

Of course, absolutely no one ever actually does this, or reads the manual in the first place.

On motorcycles, the manual usually recommends flushing every two years. Some manuals actually call for replacing the brake lines every four years, which is expensive and silly.

 

[pmiranda]

If somebody topped off the fluid with the pads worn down then if you don't bleed off some fluid you'll have to suction it out of the reservoir or it will overflow when you push the pistons in. I think the lines have enough fluid in them that anything you push back from the calipers would never reach the ABS pump.
Also... if I don't know the fluid has been flushed in the last year, I flush it, so my bleeder screws never get seized from lack of use.

 

[fsae0607]

I think it's an urban myth, since I know many people that don't crack the bleeder screws and push the pistons back in with no problems.

When I do brakes, I always crack the bleeders, retract the pistons and go ahead and flush the system. As cheap as brake fluid is, it's good insurance to have fresh fluid in your system.

 

[matt_i]

The hydraulic foundation brakes are the same antilock or not, out at the wheel area.

Personally I would not kink or pinch the brake hose trying to block fluid flow. The downside is a damaged hose with little to gain....

I flushed the brake fluid on a 2000 grand prix that was falling apart from rust after 225k miles, at around the 180k-200k mark, when I lost two hard pipes to corrosion in successive winters. I was amazed at how clean the fluid was and Im pretty sure it had never been changed before as I got it from my brother who would not have done this type of maintenance.

 

[NYBODYMAN]

Opening the bleeder=most likely have to bleed the system when done. Just push them back in and check the reservoir when your done.

 

[Reg1952]

Been in the trade 35 year. Have seen it twice after pushing pistons back that an ABS module had to be replaced. Sludge in calipers plugged up ports in module. Now in saying this do I open bleeders? Nope.

 

[T_R]

I never open bleeder nor does anyone I work with. In 25 years I have never seen a failure related to this.

 

[firworks]

I've never heard of opening the bleeder when pushing in a piston but I have heard of opening the reservoir for the reason that when you push the pistons back you might overflow and some might need to be removed.

 

[redmondjp]

I always open the bleeder screws when doing this, every single time. You don't want to push old, dirty and water-laden brake fluid back up into your system.

I have become religious about changing my brake fluid every 3-4 years (did all five vehicles this fall). First I use a vacuum extractor to remove all of the fluid from the master cylinder reservoir. Then I open the bleeder screw, compress the caliper piston, and then let the system gravity bleed until I get clean, clear fluid out. Repeat at all other corners.

At the shop I worked at, this was standard practice during any brake job.

 

[bubinga]

I always open the bleeder screws when doing this, every single time. You don't want to push old, dirty and water-laden brake fluid back up into your system.

I have become religious about changing my brake fluid every 3-4 years (did all five vehicles this fall). First I use a vacuum extractor to remove all of the fluid from the master cylinder reservoir. Then I open the bleeder screw, compress the caliper piston, and then let the system gravity bleed until I get clean, clear fluid out. Repeat at all other corners.

At the shop I worked at, this was standard practice during any brake job.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This,
I always like to open the valve if I can.

 

[c39er]

I have always opened the bleeder on hundreds of brake jobs when pushing in the caliper pistons. Saves from having to siphon off the M/cyl and promotes adding clean new fluid when not doing a proper flush and fill.

 

[mikeceli]

I always open the bleeder screws when doing this, every single time. You don't want to push old, dirty and water-laden brake fluid back up into your system.

I have become religious about changing my brake fluid every 3-4 years (did all five vehicles this fall). .............. Then I open the bleeder screw, compress the caliper piston, and then let the system gravity bleed until I get clean, clear fluid out. Repeat at all other corners.

At the shop I worked at, this was standard practice during any brake job.

ABOVE IS THE CORRECT WAY. How many "pros" who "never saw a problem" pushing dirty fluid upstream, had there customers ABS fail months later and never heard about it?

My shops always followed PROPER, repair procedures.

 

[Radio Flyer]

I work in a fleet shop, we open the bleeder and bleed the brakes as a standard practice during routine brake service.

 

[joe_padavano]

If somebody topped off the fluid with the pads worn down then if you don't bleed off some fluid you'll have to suction it out of the reservoir or it will overflow when you push the pistons in.

That is exactly correct - you siphon the extra from the reservoir in the MC, which is before the sealed part of the brake system and thus there is no chance of allowing air to enter.

 

[joe_padavano]

ABOVE IS THE CORRECT WAY. How many "pros" who "never saw a problem" pushing dirty fluid upstream, had there customers ABS fail months later and never heard about it?

My shops always followed PROPER, repair procedures.

Really? If this is the "PROPER" way, why is it not documented in any factory service manual that I own?

But then, if your shop follows PROPER repair procedures, then obviously the shop must have a copy of the factory manual for every vehicle it services...

 

[joe_padavano]

I always open the bleeder screws when doing this, every single time. You don't want to push old, dirty and water-laden brake fluid back up into your system.

You do realize that every single time you press on the brake pedal and release it, that old, dirty, water-laden fluid moves backward from the wheels into the M/C, right?

If the brake fluid is really that crappy, you definitely should flush it. As others have pointed out, flushing fluid periodically is a good idea and IS recommended service by many automakers. Flushing and proper bleeding is NOT the same as cracking a bleeder screw while pushing the piston back into the caliper, however.

 

[Speed4Life]

I always just crack the master cylinder cap open and push em back in. Never had an issue in 25 years.

 

[CJM8515]

I lost track of how many brake jobs Ive done over the years. NEVER have I done this and never have I had an ABS fault. You are more likely to snap the bleeder off than anything.

 

[redmondjp]

For those in areas where rust is an issue, I can see the risk of breaking a bleeder screw. But for everybody else, get the fluid out - you have to change it regularly anyways and when you are retracting the piston is the perfect time to do it.

The brake fluid absorbs moisture which lowers its boiling point and causes corrosion.

If you are in an area with a rust issue, remove the bleeder screws (on new or existing parts) and coat the threads with anti-sieze. Then use the rubber caps on them as well.