Brake system bleeding, master cylinder bleeding + a damage warning - PeachParts Mercedes-Benz Forum

whunter · #1 03-26-2006, 06:07 PM

Bench Bleeding
http://www.valvoline.com/carcare/articleviewer.asp?pg=res20020701bm&cccid=5&scccid=9

Installing a new master cylinder requires a bench bleed to ensure all the air is removed from the unit.
http://www.misterfixit.com/brakbld1.htm

Bench Bleeding the Master Cylinder
http://www.custompistols.com/cars/articles/dw_benchbleed.htm

http://www.google.com/search?hl=en&lr=&q=how+to+bench+bleed+the+master+cylinder&btnG=Search

SatRoc · #2 03-26-2006, 06:36 PM

Thanks Whunter! Very helpful information.

whunter · #3 10-02-2011, 01:32 AM

This can happen to even the most experienced mechanic, "Especially" on a high mileage car.
The old school manual brake pedal "down" - "up" - "down" - "up" bleed method risks over-stroking the master cylinder.
The master cylinder piston seals can get scored if they're pushed into a normally unused - corroded, region of the master cylinder's bore.
If this happens, you'll have little or no brake pedal, and will need a new master cylinder.
I strongly recommend using a pressure bleeder to avoid the issue.

leathermang · #4 10-02-2011, 05:00 PM

I searched for the nipples for bench bleeding mine for a while.. since they are metric.... finally found them at NAPA.... I think the kit had both SAD and METRIC multiple sizes for less than $10... just remember where you store it and you are fixed for life...

whunter · #5 10-03-2011, 01:35 AM

Quote:

Originally Posted by leathermang

I searched for the nipples for bench bleeding mine for a while.. since they are metric.... finally found them at NAPA.... I think the kit had both SAE and METRIC multiple sizes for less than $10... just remember where you store it and you are fixed for life...

I cheat.

Home depot or Lowe's always have a cheap one gallon bug sprayer.

#1. Buy it, the cheap sprayer I got today cost me $8.99.
#2. Buy a quart or gallon of brake fluid.
#3. Rip or cut the wand nozzle off.
#4. Replace the wand nozzle with a piece of vacuum hose that fits the tube + is large enough to fit over the master cylinder line port.
#5. Put at least a quart of brake fluid in the bug sprayer.
#6. Pump up the bug sprayer.
#7. Mount the master cylinder/reservoir assembly in a vice or on the car.
#8. Remove the reservoir cap.
#9. With one hand, hold the vacuum hose firmly on the master cylinder line port you want to bleed.
#10. Squeeze the wand trigger with your other hand.
#11. You should hear a brief bubbling gurgle, but keep reverse filling until you are sure that section of the reservoir is at least 1/4 - 1/2 full.
#12. Repeat steps #9, #10, and #11, on each line port.
#13. Attach the brake lines, fill the master cylinder and bleed at all four wheels as needed.

Total master cylinder bleed time is generally less than 90 seconds.

1-Gallon Economy Sprayer-1401P at The Home Depot

whunter · #6 01-02-2014, 11:20 PM

For new members.