Brake Bleeding Question?
Thread Starter
Drifting
Joined: Jan 2001
Posts: 1,970
Likes: 21
From: Denville NJ
Brake Bleeding Question?
I just installed a new master cylinder which I bench bled before installing. I know that I have to bleed the entire brake system at this point. The question I have is should the brake pedal be somewhat firm before bleeding the system? Right now the pedal goes down to the floor and does not build up resistance as I pump the pedal with the engine off. Did I not bench bleed the cylinder properly or will the pedal come up when I bleed the system. I would hate to bleed the system only to have to do it all over again if the cylinder has to come off. Thanks for any help.
Race Director
Joined: Jun 1999
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From: Merritt Ils Fl
If you bleed the system the master cylinder will fill. Start with the RR thel LR then RF and LF last. Don't know what type of bleeder you have but a clean mayo jar works very well. Run a piece of tubing from the bleeder valve to the bottom of the jar with enough fluid in the jar to cover the end of the tubing. Open the bleeder valve and have someone pump until you get clean fluid with no bubbles. Close the bleeder valve and goto the next wheel. Make sure you don't let the master cylinder get too low. This is a neat and clean method that insures both a flushed system as well as one free of air.
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Start the engine and begin to bleed the system, beginning with the farthest point.
I cracked open the bleeder, installed a length of hose over the end and imersed the other end into a can of brake fluid. This assured that as I pumped the brake air would not be sucked back into the system and it's easy to keep an eye on the fluid level in the MC.
I cracked open the bleeder, installed a length of hose over the end and imersed the other end into a can of brake fluid. This assured that as I pumped the brake air would not be sucked back into the system and it's easy to keep an eye on the fluid level in the MC.
Thread Starter
Drifting
Joined: Jan 2001
Posts: 1,970
Likes: 21
From: Denville NJ
Originally Posted by Muffin
If you bleed the system the master cylinder will fill. Start with the RR thel LR then RF and LF last. Don't know what type of bleeder you have but a clean mayo jar works very well. Run a piece of tubing from the bleeder valve to the bottom of the jar with enough fluid in the jar to cover the end of the tubing. Open the bleeder valve and have someone pump until you get clean fluid with no bubbles. Close the bleeder valve and goto the next wheel. Make sure you don't let the master cylinder get too low. This is a neat and clean method that insures both a flushed system as well as one free of air.
Do I bleed with the engine running or off?
Thread Starter
Drifting
Joined: Jan 2001
Posts: 1,970
Likes: 21
From: Denville NJ
Originally Posted by 65Z01
Start the engine and begin to bleed the system, beginning with the farthest point.
I cracked open the bleeder, installed a length of hose over the end and imersed the other end into a can of brake fluid. This assured that as I pumped the brake air would not be sucked back into the system and it's easy to keep an eye on the fluid level in the MC.
I cracked open the bleeder, installed a length of hose over the end and imersed the other end into a can of brake fluid. This assured that as I pumped the brake air would not be sucked back into the system and it's easy to keep an eye on the fluid level in the MC.
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
Originally Posted by CG77VETTE
I just installed a new master cylinder which I bench bled before installing. I know that I have to bleed the entire brake system at this point. The question I have is should the brake pedal be somewhat firm before bleeding the system? Right now the pedal goes down to the floor and does not build up resistance as I pump the pedal with the engine off. Did I not bench bleed the cylinder properly or will the pedal come up when I bleed the system. I would hate to bleed the system only to have to do it all over again if the cylinder has to come off. Thanks for any help.
Race Director
Joined: Jun 1999
Posts: 14,924
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From: Merritt Ils Fl
I don't think it makes a lot of difference if the engine is running or not. I do mine with it off.
vinnies87, I was taught to start with the caliper the fartherest away from the master cylinder and work toward it. That is RR,LR then RF and LF last. Haynes says RR,LR,LF then RF. I wonder if it really makes a lot of difference.
vinnies87, I was taught to start with the caliper the fartherest away from the master cylinder and work toward it. That is RR,LR then RF and LF last. Haynes says RR,LR,LF then RF. I wonder if it really makes a lot of difference.
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Thread Starter
Drifting
Joined: Jan 2001
Posts: 1,970
Likes: 21
From: Denville NJ
Originally Posted by AZC4Guy
I sure hope the4 bolt at the end of the rod doesn't get out of adjustment for you. This really threw me for a lopp for a while.
Team Owner
Joined: May 2002
Posts: 24,337
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
You want it extended out to the point where it comes close to the piston without touching it. You can tell by slipping the m/c on there when the pushrod is too long.
My question is whether or not running the engine causes that pushrod to move. Until I check that, I'm not 100% sure that tip on adjusting it is correct.
My question is whether or not running the engine causes that pushrod to move. Until I check that, I'm not 100% sure that tip on adjusting it is correct.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Get a MityVac off ebay did mine in about an hour.The MityVac was ~$30 with all the fittings for the brake bleed as well as vacuum testing.Just fill the MC up and bleed till clear.Boy it was nasty too now I can see the bottom of the MC.I used Prestone Dot3 synthetic and the brakes work much better.This is one tool I will use again much easier than manually pumping the brake.Some guys use speed bleeders they replace the fitting you have on the calipers.Use some PB Blaster on the fittings the day before you do it and just before you do it hit them again with it.They all loosened with no trouble.You do not start the engine to do it this way and it makes it tuff to get air in the system this way.
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
On my first attempt to bleed the system, with engine off, I pressed too hard on the brake pedal (due to no back pressure) and jammed the MC.
When it came time to bleed the system with the 2nd MC I ran the engine and had no problem getting enough pedal to force fluid out the bleeder.
When it came time to bleed the system with the 2nd MC I ran the engine and had no problem getting enough pedal to force fluid out the bleeder.
Melting Slicks
Joined: May 2004
Posts: 2,524
Likes: 10
From: Lufkin Texas
St. Jude Donor '05-'06
Originally Posted by Muffin
vinnies87, I was taught to start with the caliper the fartherest away from the master cylinder and work toward it. That is RR,LR then RF and LF last. Haynes says RR,LR,LF then RF. I wonder if it really makes a lot of difference.
Drifting
Joined: May 2005
Posts: 1,302
Likes: 1
From: Tomahawk WI
Originally Posted by CG77VETTE
Are you referring to the rod that sticks out of the booster? If so, what did you have to do to adjust it?
You have to use a pair of vice grips to hold the cylinder the bolt screws into. It was impossible to do it by feel for me as far as having it just miss the master cylinder. What happened would be that after I turned the bolt, then put the MC back on.. the wheels would spin freely (had front tire off ground for testing) Then I'd start car and apply the brakes... the brakes would then remain in contact w/ the rotor after released. so, by trial and error, I would remove the MC, turn the bolt a little bit, put MC on, test, rinse and repeat. Important note... you should turn the bolt as little as a quarter turn each time.
Disclaimer: There may be a better way to do this...... I am unaware of it.