New Clutch Pedal Falls to Floor Randomly

[drummerboi]

Hey guys, it has been a long time since I posted on this forum. Need some logic diagnosing a new clutch master cylinder. Car is a 93 325i.

I bought the cylinder from an ebay user. It looked new and no sign of it being used. It is a FTE brand.

After installing and bleeding it manually (pumping the pedal) the pedal worked fine for 6 months. Out of nowhere, it fell to the floor. Had to either wait or trying pumping to get pressure again. Thinking that since this is practically a new part, it couldn't be the cylinder so I decided to bleed it again. This time I pressure bled it with a homemade pump. Worked great. Pedal worked good for about 3 weeks. After that, fell to the floor again.

I'm stomped... the slave cylinder was replaced 2 years ago. The car was driven minimum since I got an e46.

Could it just be a faulty master cylinder? Air keep getting into the cylinder/lines? If it is the cylinder, why does it work fine for a period of time? If air keeps getting in the system, why I can't I find a leak when I pressure test the system???

Help..Ideas??? Thanks...

[66 6]

If your not seeing any fluid anywhere than the issue is between low fluid in the brake master, loose hose to the clutch master or the clutch master itself.

[drummerboi]

If your not seeing any fluid anywhere than the issue is between low fluid in the brake master, loose hose to the clutch master or the clutch master itself.Don't recall seeing any fluid... fluid level is right above the top line... will check on the hose...

Anyone knows if air in the system will cause the pedal to fall down?

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[pbonsalb]

I think it can. Did you bleed your slave after replacing the master? The master is actually self bleeding after enough pedal pumping. I bleed the slave manually by removing it and holding it with the nipple up, opening bleed, depressing piston and holding depressed while closing bleed, and repeating several times. Watch reservoir level when bleeding because if it drops below clutch port, air will be introduced into the line you are bleeding.

[bluptgm3]

I think it can.
Did you bleed your slave after replacing the master? The master is actually self bleeding after enough pedal pumping.

I bleed the slave manually by removing it and holding it with the nipple up, opening bleed, depressing piston and holding depressed while closing bleed, and repeating several times.

Watch reservoir level when bleeding because if it drops below clutch port, air will be introduced into the line you are bleeding.

+1


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[drummerboi]

Quick question, does the car need to be jack up at all 4 corners to be level or does it even matter. I just jack up the front.