bleed master brake cylinder?

[merrill]

so, I am rebuilding my rear brakes and replacing the lines etc.

Once I get it all back together do I need to  bleed the master
cylinder?

I searched the forums for bleeding and master cylinder and did seem to find a way to bleed the master cylinder but to press the brake pedal, crack the line then tighten and release the brake pedal.

I have the mb, haynes manuals and I could not find out how to bleed the cylinder either.

any feedback would be helpful

thanks
matt

[ted280sl]

Matt,
  Pumping the breaks is the standard manner of leeding the system. It takes two people and it takes time. I purchased a suction pump which turns the job into a one man job but, it still takes some time. The suction hand pump attaches at the bleed nipple and draws air and fluid out of the system.
Ted 1969 280SL

[Naj ✝︎]

I suggest using a 'mity vac'
I saw one at Sears the other week for around $35.00 (plastic body)

naj

65 230SL
68 280SL

[lurtch]

Hello to All

There is actually an even easier way than using the MityVac.  I have had good success with what I will call the "reverse snorkel-tube" approach.  First, locate some clear vinyl tubing that  will  attach tightly over the tip of the bleed fitting on the caliper.  Then fill it with brake fluid. (YES- it is Messy) Then put some small (preferably clear) jars in position so that the tubing can reach to the bottom of them. Fill the jars half way and immerse the end of the tubes. Open the bleed screws and pump the pedal untill all signs of air bubbles are gone. As long as the tube stays below the jar fluid level , no air can re-enter the system. I used this method to entirely purge my darkened old fluid.

 Larry in CA

[ja17]

Hello Larry,
Yes, I have been using your method to bleed brakes by myself for forty years! Old windshield wiper tubing is just the right size diameter.
It will not work on ABS systems however.

Joe Alexander
Blacklick, Ohio

[Ben]

Larry can you elaborate please, does the jar need to be higher than the caliper or am I mistaking the principle of syphoning for your "snorkel" method ?

Do you actually fill this tube with fluid, it DOES sound messy, how do you achieve this ?

I always simply had a helper and fitted a tube over the caliper, other end in a filled jar and got my helper to push down whilst I opened then shut the bleed nipple. This ensured no air got into the system. Then once I know the tube has been purged its the normal, pump, open, close, pump, open close blah blah ( stating the obvious I know but .........)

Joe can you explain why it doesn't work with ABS cars ?

Regards,
Ben in Ireland.
'64 230SL 4sp.