Free brake fluid pressure bleeder

[Aurel]

Today I replaced my brake lines with stainless steel ones, and my brake fluid with ATE super blue. By far the best method for replacing the brake fluid is pressure bleeding from the top, but the pump costs $45. I did not have the pump, but I had a $15 pressure sprayer for the backyard that worked perfectly, hooked up to reservoir return line. No helper needed, perfect result, firm pedal.

[HarryD]

Good deal. To be careful you do not over pressure you brake reservior system, you might want to add a 0-30 psi pressure gauge to your set up. You only need 10-12 psi for the bleeder to work properly.

[docrodg]

Just linked this on another thread... nice trick there!

[MrJTP]

That's pretty good! And you don't have to worry about pinching off the overflow tube.

[ruf-porsche]

Where's the free brake fluid pressure bleeder?
I am too late?

[EarlyPorsche]

I'll take it but you didn't mention who pays shipping!?

[911pcars]

I suggest you use the pressure sprayer for air pressure only, no fluid. That avoids contaminating the fresh BF with whatever was in the sprayer before. If the system needs more fluid, relieve the pressure on the MC, unscrew cap and refill, reinstall cap, then continue bleeding.

Not having BF in the sprayer reduces the chances of the pressure hose accidentally separating from the breather tube and spraying the trunk and paint with BF. Most owners will not be happy when this happens.

Sherwood

[Zeke]

Originally Posted by ruf-porsche

Where's the free brake fluid pressure bleeder?
I am too late?

Gravity is free and the gravity system works great.

[911pcars]

Originally Posted by milt

Gravity is free and the gravity system works great.

Despite my earlier suggestions as to pressure sprayer use, I'm with Milt as to the advantages of gravity bleeding. From my seat-of-the-pants research, gravity bleeding/fluid replacement usually saves about a liter of $$ fluid compared to bleeding methods using pressure or vacuum.

Sherwood

[rnln]

Aurel,
1 question. After the fluid in the resevoir lower, you just open the resevoir cap and fill fluid, close the cap, and pump. Am I correct?

Milt, sherwood,
I never done gravity. Is it just simple as fill the fluid, open the bleeder, go for a coffee, come back to check the fluid flowing?
Do you remember how long it would take the left-rear caliper to complete?

Thanks.

[sc_rufctr]

Good to see someone using their brain instead of opening their wallet...

Old School

[911pcars]

Originally Posted by rnln

Aurel,
1 question. After the fluid in the resevoir lower, you just open the resevoir cap and fill fluid, close the cap, and pump. Am I correct?

Milt, sherwood,
I never done gravity. Is it just simple as fill the fluid, open the bleeder, go for a coffee, come back to check the fluid flowing?
Do you remember how long it would take the left-rear caliper to complete?

Thanks.

Only if the coffee is nearby and ready to pour. You should be present to monitor the fluid level in the MC (keep filled). Attach plastic tubing to the bleeder screw and position vertically so the open end faces upward. Open the bleeder screw and allow gravity to push fluid through the system and into the tube as shown. Observe air bubbles exit the caliper. Depress the brake pedal slightly to encourage fluid movement. Periodically, tilt the open end of the tube into a container to get rid of excess/old fluid. Once bubbles disappear, tighten the bleeder screw and remove the tube.



The bottle shown is a vented brake bleeding bottle to catch excess fluid; has a magnet attached to position the tubing (Harbor Freight, about $5). It's optional. Any fluid container works.

Sherwood

[Aurel]

Originally Posted by rnln

Aurel,
1 question. After the fluid in the resevoir lower, you just open the resevoir cap and fill fluid, close the cap, and pump. Am I correct?

Milt, sherwood,
I never done gravity. Is it just simple as fill the fluid, open the bleeder, go for a coffee, come back to check the fluid flowing?
Do you remember how long it would take the left-rear caliper to complete?

Thanks.

Yes, you pump, bleed one wheel starting with passenger rear, refill, pump again for next wheel. Only have to pump once per wheel, it is very fast and does not use much brake fluid; I have more than half the ATE super blue leftover. My take on gravity is that it is slower and wastes more fluid because bubbles don`t show up as well. And my driveway is on a slope, so it might not have worked.

[Aurel]

Originally Posted by 911pcars

I suggest you use the pressure sprayer for air pressure only, no fluid. That avoids contaminating the fresh BF with whatever was in the sprayer before. If the system needs more fluid, relieve the pressure on the MC, unscrew cap and refill, reinstall cap, then continue bleeding.

Not having BF in the sprayer reduces the chances of the pressure hose accidentally separating from the breather tube and spraying the trunk and paint with BF. Most owners will not be happy when this happens.

Sherwood

This is what I did, no fluid in the pressure sprayer !

[911pcars]

Originally Posted by Aurel

Yes, you pump, bleed one wheel starting with passenger rear, refill, pump again for next wheel. Only have to pump once per wheel, it is very fast and does not use much brake fluid; I have more than half the ATE super blue leftover. My take on gravity is that it is slower and wastes more fluid because bubbles don`t show up as well. And my driveway is on a slope, so it might not have worked.

Not sure if Aurel is referring to bleeding or replacing fluid nor am I advocating one method superior over another; each method has their advantages.

As for gravity bleeding, the tube added to the open bleeder screw essentially extends the hydraulic system and makes it easier for air bubbles to escape and to observe. In fact, one could use a longer tube, it's open end positioned as high as the reservoir, and allow air bubbles to escape at their leisure (fluid will seek it's own level). Have 2-3 cups of java while you're waiting, then return, tap the caliper with a metal object to loosen residual bubbles, then go for another refill. I do this with all 4 calipers simultaneously, but you have to be more observant of the fluid levels in the reservoir and each individual tube.

Replacing old with new fluid requires some force to push the new fluid through. Gravity is just a gentler, albeit lengthier, method to accomplish that. Air bubbles tend to cling to the system walls despite positive pressure applied to the fluid and this translates into BF, old and new, continuously forced out of the bleeder screw until the very last air bubble is forced to exit.

In addition, if your brake fluid requirements are high (as with expensive Castrol SRF), you may want to rethink the method employed to bleed the system.

Sherwood

[rnln]

sherwood, 2 questions.
1- the method you described with picture above is to bleed air only, or also replace all old fluid?
2- will it be better, easier for old fluid to come out, if the bottle's position is below the bleeder valve?
Thanks.
I alwasy do the pumping, 2 men, method without problem, but don't want to have chance of damaging the seal. If there is a better/safer way, I would use it.

[911pcars]

Originally Posted by rnln

sherwood, 2 questions.
1- the method you described with picture above is to bleed air only, or also replace all old fluid?

2- will it be better, easier for old fluid to come out, if the bottle's position is below the bleeder valve?
Thanks.
I alwasy do the pumping, 2 men, method without problem, but don't want to have chance of damaging the seal. If there is a better/safer way, I would use it.

If you want to drain the system or just remove some fluid, merely tilt the top of the tube downward into the bottle or other catch can.

The 2-man, pump- hold- open/close bleed valve routine works, but it has inherent issues, mainly, the need for a second willing body, not to extend the MC piston too far for fear of tearing a sealing cup and preserving spousal relationships. Using this method, a block of wood under the pedal is a pretty good, no-brainer setup.

I met some guy who used to work at the ship port, where the foreign cars are off-loaded awaiting shipment to dealers. One of his jobs required bleeding the brakes of every car prior to truck p/u. His short-cut method was merely to open the bleeder screws and allow the BF to dribble out. Not sure about the BF path between caliper and ground, but that's how he did to 100's of vehicles.

Sherwood

[rnln]

ok, so the summary is:
To let air escape: bottle higher than bleeder valve.
To replace fluid: bottle below the bleeder valve.
Correct?

[sc_rufctr]

This is what I use. I works every time and I use it for a myriad of other tasks.

(it wasn't free )

[911pcars]

Originally Posted by rnln

ok, so the summary is:
To let air escape: bottle higher than bleeder valve.
To replace fluid: bottle below the bleeder valve.
Correct?

Air bubbles will rise in a liquid. Thus, orient the tube vertically. The bottle is just a convenient receptacle for excess fluid. If the bottle is attached, arc the tube and bottle downward to catch the fluid. If the location of the bottle is below the fluid level in the reservoir, the fluid will naturally rise and empty into the bottle.

Sherwood