power brake bleeder - PeachParts Mercedes-Benz Forum

kramlavud · #1 03-19-2004, 07:14 AM

The Mercedes Bible for W124 models says a power bleeder must develop 30psi if the car has ABS. Does anyone know if the Motive Products power bleeder has this capacity?
regards,
Mark

ctaylor738 · #2 03-19-2004, 09:05 AM

I have gotten mine to 25, and it didn't show any sign of slowing down.

#3 03-19-2004, 09:12 AM

The instructions say to pump to 20. I have not exceeded that because I have a manual transmission and I'm afraid that it will blow off the clutch master cylinder tube.

With an automatic, I expect that you could go this high. That said, you only need that much pressure if the system has been open and has air in the lines. If you are simply flushing, 15 or 20 will get the job done.

Hope this helps,

kramlavud · #4 03-19-2004, 12:14 PM

Larry,
I wonder why the "Bible" says 30psi is needed to flush the Antilock Braking System?
Mark

#5 03-19-2004, 04:38 PM

I expect that it is so that there is enough pressure to prevent air from reversing its way back in. As I say, I don't think this is a problem for flushing, only for bleeding. He could have been using the words interchangably.

I hesitate to say it, but I'm not just blown away impressed with that book anyway.

Have a great day,

#6 03-19-2004, 06:21 PM

I once attended a brake seminar at a Mercedes dealership put on by the M-B Club. The resident brake *expert* said you needed 29 lbs. for ABS but then the guy wasn't all that knowledgable.

One thing he did say was that was interesting was when the dealership stopped using the old two man bleeding procedure, they stopped having to replace master cylinders.

ericnguyen · #7 03-19-2004, 06:30 PM

The reason is because the ABS unit has a lot of internal microtubes and valves in it, so it may require higher hydraulic pressures to push the new brake fluid through them all.

The motiveproducts' Power Brake Bleeder gauge can go as high as 30 PSI, and I tried that pressure before on my c220 without any problem. However, I believe that 25 PSI is good enough because the fluid already came out forcefully.

Eric

kramlavud · #8 03-19-2004, 06:39 PM

Thank you all.
regards,
Mark

afmcorp · #9 03-20-2004, 01:44 PM

well that makes some sense. i just did the fronts on my 87. i pumped up the motive 20 plus psi and nothing came thru the wheel bleeder. i tried and tried but nothing. getting aggravated i pushed more pressure and still nothing. i even removed the bleeder center completely and nothing. so i had my wife get in and do the 123 hold still nothing. soooo..... after several attempts i told her to pump and then stomp the hell out of the pedal and if it goes to the floor too bad well finally i got a trickle of juice so i kept it up till i got new juice thru the bleeder.

the only thing i could think of was the abs unit must be doing something to the pressure or flow. i didn't know from what but the brakes work absolutely perfect. good pedal feel good height and stops great.

so i guess this action is normal???

#10 03-20-2004, 07:47 PM

If you're going to bleed with the two man method, you will have to do it with the engine running. This will allow the booster to apply the pressure you need.

Good luck,

afmcorp · #11 03-20-2004, 08:45 PM

that was the puzzling part. the engine was running the bleeders were loose and i had also taken them out to be sure there wasn't anything blocking them.

in fact i was getting upset with my wife because i thought see wasn't doing the old 123 hold routine right. i also thought the feed line to the master cylinder might be what was wrong because i could not get the air pocket out of the line. no matter where i held the bottle up even or below the cylinder there was an air pocket. so finally i got a spurt out then the bottle started to work. i had it pumped up to the max and a light trickle finally started to flow.

both sides did the same but the brakes are fine and were right out of the gate.

MBDad777 · #12 03-23-2004, 05:56 PM

I had the same thing happen on my '99 C280 Sport but still don't know what's wrong. I use a power bleeder and the fluid comes out the front like a fire hose but barely trickles out the back. Anybody else got any solutions to this?

ericnguyen · #13 03-23-2004, 09:11 PM

The brake reservoir is partitioned into 2 chambers (one for the 2 front brakes and the other for the 2 rear ones), so you must make sure that brake fluid fills both of them. The reason for the existence of 2 separate chambers is because either the 2 front brakes or the 2 rear brakes will still function even if the other 2 brakes are leaking or not functioning.

The power bleeder is small and may not provide enough constant pressure if you try to bleed all 4 brakes at the same time, so it's better to do it once at a time (or 2 front, then 2 rear).

I used Power Bleeder on 4 different MB cars and it worked very well.

BTW, make sure that the 2 brake reservor caps and/or 2 brake reservoir grommets are good and not leaking before applying the higher pressure. Otherwise, brake fluid will spill everywhere on your car paint and damage it.

Eric

#14 03-24-2004, 09:16 AM

Eric brings up a great point. I have trouble sometimes getting the cap threaded onto the reservoir such that it does not leak.

Have a great day,

MBDad777 · #15 03-24-2004, 12:11 PM

The only way I was able to suppress leaking was to double-up the rubber washer under the cap.