MC Bench Bleed Procedure
Race Director
Joined: Jul 2004
Posts: 12,696
Likes: 329
From: Scottsdale Arizona
Originally Posted by 69autoXr
What is the procedure for bench bleeding a master cylinder? Is it necessary to bench bleed if the master has bleeders?
Tech Contributor
Joined: Aug 1999
Posts: 15,156
Likes: 3,965
From: Connecticut, USA
I always use bench vise to bleed a M/C if new or it has run dry. I've tried the various tools to do this but found the best thing to do was go to NAPA and get the metric brake adapter lines that fit the M/C (2 sizes) and cut off one end. Curl it up and into the M/C reservoir and use a punch or rod to bleed by pressing the piston several times until there are no more air bubbles in the fluid.
Gary
Gary
Drifting
Joined: Jan 2002
Posts: 1,645
Likes: 11
From: Schaumburg IL
MC Bleeding
Just use the tubes from the NAPA kit that go from the outlets of the MC bent to fit back into the cylinder bowls. Depress the piston s-l-o-w-l-y and let it out slow or you will aearate the fluid in the cylinder bore. This is a common problem. After 3-4 pushes and releases let the thing sit for 5 minutes and go back and do it again. This will let any trapped air rise and get out. Then when you bleed your brakes don't let the fluid get below the half way point in the front or rear or you get to practice all over again.
Melting Slicks
Joined: May 2002
Posts: 2,508
Likes: 0
From: Wisconsin
I think the running of the hoses back up and in is the better way, but what about the other way, using the block off plugs. That is the method that was recommended with my MC when I did. Basically the same except plugs are screwed into the line holes.
Le Mans Master
Joined: Jan 2001
Posts: 6,723
Likes: 1,377
Master Cylinders w/ bleeders
I wouldn't bother bench bleeding a master cylinder if it has the installed bleeders.
My old master cylinder had installed bleeders(both), and even though my present one feels fine, my old one felt just super when I would bleed both the brakes and the master cylinder. I had to replace it because the cylinder was scored.
I spent a whole day looking locally for a master cylinder with installed bleeders before I bought a new replacement without the bleeders from NAPA.
By the way; I use a homemade pressure bleeder for my brake bleeding.
My old master cylinder had installed bleeders(both), and even though my present one feels fine, my old one felt just super when I would bleed both the brakes and the master cylinder. I had to replace it because the cylinder was scored.
I spent a whole day looking locally for a master cylinder with installed bleeders before I bought a new replacement without the bleeders from NAPA.
By the way; I use a homemade pressure bleeder for my brake bleeding.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Originally Posted by Schmucker
I think the running of the hoses back up and in is the better way, but what about the other way, using the block off plugs. That is the method that was recommended with my MC when I did. Basically the same except plugs are screwed into the line holes.
Le Mans Master
Joined: Jan 2001
Posts: 6,723
Likes: 1,377
Brake bleeding kit at Carquest
By the way; if you do want to bleed your Master Cylinder I bought a plastic bleeding kit at Carquest for about 10 bucks ...it comes with various sizes of screw-in taps and a piece of black rubber hose. I replaced the black rubber hose with clear Tygon tubing just so I could see if any bubbles came through.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Le Mans Master
Joined: Oct 2001
Posts: 5,145
Likes: 125
From: The Motor City
Last time, I just bled the MC thru the top with a handheld MityVac. I stuck the hose into the hole and sucked out the air. It worked just fine and gave a rock hard pedal after I bled all 4 calipers again.
Chris- If you don't have a MityVac, let me know and you could borrow mine.
Chris- If you don't have a MityVac, let me know and you could borrow mine.
Thread Starter
Melting Slicks
Joined: Jan 2004
Posts: 3,247
Likes: 210
From: Detroit MI
Thanks for all the replies. I recently found out that I've been using a manual master on my power system, which is the reason why makes brakes have been so ridiculously touchy and prone to lock up. I got used to them, thinking that must be how they are. It was only after a few more experienced guys drove my car and commented on the brakes that I started wondering. When I installed the master 5 years ago I just didn't know any better about the difference between the manual and power masters.
I didn't bench bleed the master when I installed it 5 years ago, and never had a problem with air in the master. It has bleeders, so I must've been ok for that reason, but when I put the new master on I wanted to do bench bleed it so that I knew how to do it.
I didn't bench bleed the master when I installed it 5 years ago, and never had a problem with air in the master. It has bleeders, so I must've been ok for that reason, but when I put the new master on I wanted to do bench bleed it so that I knew how to do it.
