Master Cylinder

[timkins]

I just installed an MP master cylinder and combination valve in my 32 sedan. Master cylinder is below the floor NO power brakes. In my haste to get the master cylinder installed and the lines fitted I forgot to bench bleed the master cylinder. I was going to only fit the cylinder BUT the next thing I knew I had installed it and the lines. Somewhere I read that you can bleed amaster cylinder by gravity by opening all of the bleeders and let it  sit. True or not? Any suggestions or help would be greatly appreciated.

[Normspeed]

I've done a couple of Ford type MCs in the last year, and bench bleed is the way to go.  I was surprised at how many pumps it took to get all the bubbles out.  Might be worth yanking it just to get it out of the way.

[tom36]

I've done it that way before.  Jack up one end and let it gravity feed.  Close the bleeders after they run clear for awhile and do the the other end.  Make sure the master stays full.  This takes awhile so find something else to do and keep checking back.  Tom..

[flt-blk]

Does the gravity bleed really work to remove bubbles or more to flush
the fluid?

I would think the movement of fluid would push bubbles out where low
pressure gravity would just go around the air bubble.

[tom36]

Does the gravity bleed really work to remove bubbles or more to flush
the fluid?

I would think the movement of fluid would push bubbles out where low
pressure gravity would just go around the air bubble.

Well, your getting a little to technical for me   All I know is that it works.  I can imagine in my head, the fluid being heavier than air, pushing out any air along the way as it (the fluid) travels to the low point and out.  Tom..

[kb426]

If your master cylinder is lower than the bleeders on the calipers, it won't work. Gravity won't make the fluid go uphill. Also, when the calipers are higher, if they suck air even alittle, you will need some kind of a residual pressure valve at the outlet of the master cylinder to keep a good pedal. A 2 lb. valve will work. How about you borrow either a pressure bleeder or a mityvac and hook to a bleeder as an option to remove the cylinder again. I was assuming you didn't mean to remove the outlet lines on the master cylinder and let it sit for several days.

[timkins]

Thanks to all who replied with suggestions. I finally went down to the garage last night and pulled the master cylinder and bench bled it the way I should have before installation. Sometimes my hands get ahead of my brain and I pay the consequences by having to redo what I just did.

[alchevy]

Just chalk it up as being a practise run...and now ya know it fits!

[river1]

this might help in the future

http://www.bmw-m.net/TechProc/bleeder.htm

later jim