Clutch master cylinder: tell me about the rubber cup/seal "thaaang"...

[fixizin]

... specifically, when reservoir is full, is that DEEP cone supposed to be squashed flat, up against the bottom of the reservoir cap? Or does it flex up and down with each press of the clutch pedal?

I understand you want to keep moisture out of the DOT 3 fluid, but why does this seal take up so much VOLUME in the small reservoir?

Thanks in advance.

 

[alwaysFlOoReD]

If you have a leak that rubber cap will stretch to fill the whole empty reservoir. First time I had a fluid leak, when I saw the reservoir the rubber was all he way to the bottom and I thought that was normal. Put in fluid and nothing changed. Didn't figure it out til a friend showed me...lol.

 

[fixizin]

... I thought that was normal. Put in fluid and nothing changed. Didn't figure it out til a friend showed me...lol.

SOOOooo... then you DO manually collapse it before topping off the fluid?

 

[BroncLander]

SOOOooo... then you DO manually collapse it before topping off the fluid?

Yes

 

[fixizin]

Hope it's not a leak at the slave... then again everything is 25 years old down there... yeah, it's probably a leak.

 

[2011Supercab]

Hope it's not a leak at the slave... then again everything is 25 years old down there... yeah, it's probably a leak.

As the clutch wears out, the slave cylinder gets extended a little and holds more fluid, perfectly normal.

Just like brake fluid goes down as the pads wear and the calipers stay extended a little bit.

 

[fixizin]

Thanks, let's hope... won't be able to crawl under and look in the bell-housing viewport until much later today or tomorrow.

PS: fluid, which is only 2 years old, looked a bit dirty... where does that come from?

 

[fixizin]

Whoa!... forgot how close the exhaust pipe is blocking that viewport... cool-down period...

... in the meantime, NO WAY that DEEP cup collapses VERTICALLY (like a condom, lulz)...

... now I do notice it's molded with 4 deep grooves, and thus 4 prominent lands, SO...

... I'm thinking it's like a BELLOWS, and those grooves expand outward as the fluid level drops...??

 

[alwaysFlOoReD]

Yes