I'm trying to get a better understanding of how the clutch master cylinders reservoir keeps the lines full of fluid without changing the level of the reservoir.

Please look at my photo I attached, does it work something like this?

In my diagram, the piston has holes to let fluid through, when the clutch is depressed, the piston hits a spring loaded diaphragm that blocks the fluid from moving back over the piston and into the reservoir.

Is this how it works?

This will give me a better understanding with bleeding and flushing the clutch out. I mixed some Dot 5 by accident and need to flush with alcohol before replacing the DOT 4 fluid. Thanks in advance all!

 

pretty sure its like this

 

Thanks for the reply, Craby. I do understand how that master works but this set-up for the 4th gens are a bit different. The reservoir and fitting to the slave are reversed. Here's mine: http://image.superchevy.com/f/958878...mage_large.jpg

Looking at these photos:

http://www.alfabb.com/bb/forums/atta...1&d=1209918990

http://repairpal.com/images/managed/...r_06.19.11.png

I wonder if the port from the reservoir to the cylinder to the slave is open until the pedal is pushed down the slightest, which makes the piston is close the port to the reservoir and in turn compressing the fluid.. ?

 

might try looking in the service/shop manual. download here https://www.mediafire.com/?40mfgeoe4ctti found in the service manual section. bottom of home page.

 

Yes, the piston seal has to go beyond the port THEN the cylinder can start to compress the fluid for filling the slave.

 

I thought these cars had a closed system no res.

 

Awesome, thanks guys. I think I get it now!

When the pedal is not pressed, the reservoir is open straight through the master and down to the slave.
I confirmed this by pulling all the fluid with my mityvac from the bleed port at the slave and it emptied the reservoir.
I then backwards flushed and filled from the slave bleeder until the reservoir filled up, this way ensures there are no bubbles.

When I pressed the clutch down, fluid was not able to flow in either direction to the reservoir. This must mean the piston is blocking the flow to the reservoir.

I hope this thread helps others understand how our clutch master works, and gives them some insight on how to bleed properly.

I've bled so many different ways, and filling through the slave has indeed been the best way. My pedal has never felt this good!

**I've attached a diagram I made on how I believe it works, it's a .BMP file so may need to open in paint**

 

I thought I was right until I took it apart. The fluid actually passes one way through a rubber seal.

Here's the video of my findings:


This makes me wonder if the mity vac bleeding process takes a toll on this seal as you're forcing fluid and air out where it shouldn't come out.