Bench bleed master cylinder?

[fordsucks!]

What is the point of bench bleeding a brake master cylinder? Is there an air pocket in the MC that cannot be reached with regular two-person pump bleeding at the four corners plus prop valve?

Also, if bench bled, how is this done without getting brake fluid everywhere? How do you get the plastic bleeder stuff out and thread the metal brake lines back in without making a mess?

 

[Wes Harden]

If you bench bleed the master, bleeding the system goes much faster. Use much less brake fluid.
Also you can falsely believe all the air is out of the system, when there may be some left in the Master.

 

[diesel4me]

I just bolt the master onto the booster,put the two plastic fittings & hoses that come with it to bench bleed it back into the fluid chambers,using a spring clothes pin or similar object to keep them clipped to the casting so they'll stay submerged,then fill the chambers and get in the truck and pump the pedal slowly about a dozen times..till no bubbles show in the hoses..

When you unscrew the plastic fittings there should only be a small amount of fluid coming out--there are check valves in the ports to prevent the fluid from just pouring out (and any air in the lines from migrating back into the cylinder causing loss of prime)..

I've replaced a dozen or more master cylinders using this method by myself,and either gravity bled the rest of the system or used a hose that fits the bleeder screws firmly and keep the other end submerged under some brake fluid in a jar--or use my home made vacuum bleeder jar that uses engine vacuum to suck the air out..

 

[Wes Harden]

Don't press to fast or the cylinder will squirt fluid up from the reservoir

 

[Magikal]

I did similar to above except i took a spare set of fittings and line, but about 8in long, and bent them back into the reservoir. Pump until no air bubbles. Yes, some spills changing the lines. I did mine on the bench clamped in a vice.

Seems i didn't bleed the master ahead of time once and was never able to get all the air out of the system until i did.

 

[diesel4me]

Some OEM master cylinders had bleeder screws right above the brake line ports too,that allowed you to bleed the master cylinder with the lines attached (with a helper to pump the pedal)..but none of the new ones I've bought have had them..

 

[Kain]

bolt in and do not connect the lines use brake pedal to bleed it. and get this kit. done it for 20 years from camaros to fords to blazers


https://www.oreillyauto.com/detail/...169?q=master+cylinder+brake+bleeder+kit&pos=2

 

[fordsucks!]

thanks all. The new AC Delco MC (china) did not come with bench bleed kit, so I picked one up.

 

[dyeager535]

thanks all. The new AC Delco MC (china) did not come with bench bleed kit, so I picked one up.

Which kit did you get? The link didn't work for me, but found a Dorman one on O'reilly's (schuck's) website. Comments stated it only came with one size of each fitting, but I believe ours have two different sizes, so no issue?

 

[fordsucks!]

Which kit did you get? The link didn't work for me, but found a Dorman one on O'reilly's (schuck's) website. Comments stated it only came with one size of each fitting, but I believe ours have two different sizes, so no issue?

i got kit 13911, haven't used it yet but this $11 kit should have all sizes. my MC is two different sizes. I'm still cleaning up the firewall and spraying the MC satin black, I'll let you know how the bench bleed goes.

the AC Delco instructions state that bench bleeding can be done without the hoses, if you're ok with making a bigger mess.

 

[Fordum]

I think I just had a Bevis and Butthead flashback when I read the words "suitable blunt stroking tool".,...... Twice.

 

[Kain]

Lol