Why pressure bleed brakes?

[M4_Johnnys]

I might be missing something obvious here, but why is everyone using those power bleeders?

What's wrong with attaching a tube with a one way valve to the brake nipple and pumping the brakes?

Is the only advantage of using a pressure bleeder is that you don't have to go back and forth from pumping the brakes to topping up the reservoir to make sure you don't suck air into the system? Using a one way valve on the nipple still makes it an easy one man job?

[allinon72]

Faster, easier, more fool proof. On most modern cars, if you get air in the ABS system it's not a good experience.

That being said, there's nothing wrong with the traditional method.

[Buckeye///M]

Faster, easier, likelihood of getting air into the system is less.

[JeffO]

Pumping brakes via traditional method produces accelerated wear of the brake master cylinders as the piston travels further. Pressure bleeder typically gives a trouble free bleed, provided you don't overpressure. Suggest 10 -12 psi max.

[FaRKle!]

Originally Posted by JeffO

Pressure bleeder typically gives a trouble free bleed, provided you don't overpressure. Suggest 10 -12 psi max.

BMW allows up to 2 bar / 29 PSI for pressure bleeding. That said, I don't see any benefit going above 20 PSI when I do it.

[bdaddylo]

Originally Posted by FaRKle!

BMW allows up to 2 bar / 29 PSI for pressure bleeding. That said, I don't see any benefit going above 20 PSI when I do it.

There's no benefit going above 12 PSI. The weak point isn't your car, but the bleeder hoses and connections.

[maniz]

$ for $ the pressure bleed kit from Harbor Freight has to be among the top 3 tools in my garage, and I have a lot of tools. I use it for the same reasons as above. When something can be done correctly and in <5 minutes per side, you don't ask questions.

[Brentis]

Ive tried pressure bleaders in past with good luck, but on my e90 m and m4 i hav e shops do to cycle the ABS system as i havent gotten best pedal feel when doing myself.

[JeffO]

Originally Posted by Brentis

Ive tried pressure bleaders in past with good luck, but on my e90 m and m4 i hav e shops do to cycle the ABS system as i havent gotten best pedal feel when doing myself.

The DIY way to cycle ABS is to turn the key on and off 4 or 5 times. Wait about 30 seconds each time. Sometimes I run engine a minute or so. Then bleed again. I don't always do this, but if doubt, try it.

[dheanswer]

Originally Posted by JeffO

The DIY way to cycle ABS is to turn the key on and off 4 or 5 times. Wait about 30 seconds each time. Sometimes I run engine a minute or so. Then bleed again. I don't always do this, but if doubt, try it.

I'll keep this in mind next time.
I used ISTA to turn on the pump the last time I did mine.

[Ferg]

Originally Posted by Brentis

Ive tried pressure bleaders in past with good luck, but on my e90 m and m4 i hav e shops do to cycle the ABS system as i havent gotten best pedal feel when doing myself.

Just had this done myself as I did not like the pedal feel after I pressure bled the brakes numerous times. Apparently they have a DSC flush cycle they run it through, who knows. I do know it firmed up the pedal feel.

[Pic18]

Originally Posted by JeffO

The DIY way to cycle ABS is to turn the key on and off 4 or 5 times. Wait about 30 seconds each time. Sometimes I run engine a minute or so. Then bleed again. I don't always do this, but if doubt, try it.

Are you saying do this while the pressure bleeder is attached? Or bleed the brakes, remove bleeder, cycle ignition then re-bleed?

[andrei.m4]

I saw an m4 video on yt with how pressure bleed work but who know if vacuum bleeder works on these cars m3/m4. Difference is instead pressure in can you make vacuum at caliper and in same time filling the can.