Clutch suddenly quit

[Centaurious]

Driving home from church my truck went from having a great working clutch to the pedal going to the floor. Five or six rapid pumps and I had enough to shift gears. If I let the pedal all the way up I lost all pressure.

The reservoir is full and I can see no leaks. looking under the dash everything is dry. I haven't been underneath yet.

I know from reading that the slave cylinders are mostly junk excepting OEM.

With the reservoir full it is probably the master cylinder that has failed, I don't think this is common.

What is your opinion?

 

[Centaurious]

Well... It's working just fine again. As best as I can figure out the check valve at the end of the master cylinder, that stops fluid flowing into the reservoir, had a piece of trash holding it open.

Looks like I need to flush the system.

 

[Explorin'VA]

Good catch. When you're filling the system it helps to unbolt the master cylinder and tilt it so that gravity bleeds the system. When it's mounted to the firewall the angle causes it to have a little pocket that traps air.