Mity-Vac M5R1 Clutch Bleed (w/ pics)


New member
Aug 2, 2019
Reaction score
New York
Vehicle Year
Make / Model
I've heard this mentioned before as a means to bleed a clutch master cylinder, but never found a thread dedicated to it, so figured I'd add one. The '89 Ranger was getting a new clutch including slave cylinder and new line between master and slave. The original one was NEVER going to disconnect from the slave so I just snipped it.

For better or worse, I tried to pump out much of the old fluid that was in the master, and then with the new line connected to the original master, I tried to bench bleed it, hanging the reservoir up high and sorta stretching the line out below. I thought I had done a good job, but in hindsight there was too much movement on the rod. But I went ahead and connected it all into the truck. Dead pedal. No clutch action at all.

Not wanting to pull things back out, I created a barbed vacuum fitting from an old reservoir cap. Be sure to also stick a small nail in the tiny breather hole. If you look close in the pic you can see that. I sealed both with some RTV.

As soon as I pulled a vacuum from the reservoir, I saw air bubbles come to the top and the fluid level drop. Ah, good, progress. I continued to do that a couple times. Then while under vacuum I stabbed at the clutch pedal over and over. I didn't push it more than about a third of the way - just lots of repeated stabs at the pedal like I was knocking at the door. Repeated a couple times to try to "shake out" any trapped air. You'll see the fluid level rise under full vacuum and then it drops back down as it gradually leaks down. Be sure not to let the fluid level drop down to the bottom of the cup.

For good measure, I gravity bled the bleeder down on the slave cylinder one more time. Hopefully it goes without saying, but you do NOT want to be pulling a vacuum from above when you open the slave bleeder.

Full clutch action when completed. Job done.

Last edited: