Gravity brake bleeding, open all bleed screws?
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 2,144
Likes: 195
From: Englewood FL
Gravity brake bleeding, open all bleed screws?
I have been gravity bleeding the brakes every few years to maintain fresh brake fluid, by first sucking out most of the brake fluid in the master cylinder, filling with new brake fluid and opening the bleeder screws one at a time starting at the right rear. Is there any reason, all six of the brake bleeders can be opened all at once? I was thinking at the very least, the left rear inner and right front could be opened at once as the master cylinder is divided.
The Haynes Manual says to start with the LR inner, LR outer, RR inner, RR outer, RF and last LF, but it does not differentiate by the method of bleeding.
The Haynes Manual says to start with the LR inner, LR outer, RR inner, RR outer, RF and last LF, but it does not differentiate by the method of bleeding.
Last edited by mark79,80; Aug 19, 2022 at 03:33 PM.
Pro
Joined: Jul 2004
Posts: 713
Likes: 61
From: Waterford CT
If you want to ensure that you fully remove the old brake fluid, do it one valve at a time. The brake fluid, like any flowing liquid, will take the path of least resistance and flow a lot of fluid out that way and less fluid into the lines with more resistance so you have no way of knowing if you have fully flushed any given line. Intuition says the longer lines to the rear will have more resistance than the short ones to the front; however, there can be anomalies like a tight hose at one corner that could fool with it. I have done it a couple times and always open only one bleeder at a time and I have observed that some bleeders flow faster than others.
Le Mans Master
Joined: Oct 2010
Posts: 6,937
Likes: 848
From: melbourne florida
2023 C3 of the Year Finalist - Modified
I use the 4 old tee shirt method. Put an old tee shirt under each caliper open the innerhalves first close them and open the outers just watch the master cylinder..
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
what if you disconnect the lines from the calipers so that any crud in the lines doesn't have the chance to get into the bottom of the calipers where it can end up jammed into the seals? or is disconnecting and reconnecting the lines repeatedly a possible bad thing and to be saved for parts replacement? or is it all pumped into the calipers already anyway?
Safety Car
Joined: Mar 2009
Posts: 4,191
Likes: 951
From: Corpus Christi, TX
The calipers are more or less bottom filled. It isn't going to change much what fluid leaves the bleeder ports to pull the lines. It isn't necessarily a bad thing to pull the lines, but every twist on a flare nut is just one more chance to round off the flats, even with a line wrench.
Gravity bleeding will catch almost everything. Had to reseal my RF caliper a couple months ago and managed to drain the MC. Gravity bleed on just that one put the brake pedal right back up to the top. 66 and earlier have (on non-power brakes anyway) a single piston MC. Youda thought all 4 would need bleeding. Didn't. Just bleed em. You'll clean most everything out.
Gravity bleeding will catch almost everything. Had to reseal my RF caliper a couple months ago and managed to drain the MC. Gravity bleed on just that one put the brake pedal right back up to the top. 66 and earlier have (on non-power brakes anyway) a single piston MC. Youda thought all 4 would need bleeding. Didn't. Just bleed em. You'll clean most everything out.
Race Director
Joined: Nov 2006
Posts: 13,248
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
On all my cars. Gravity bleed one Caliper at a time.
Race Director
Joined: May 2006
Posts: 18,737
Likes: 2,583
what if you disconnect the lines from the calipers so that any crud in the lines doesn't have the chance to get into the bottom of the calipers where it can end up jammed into the seals? or is disconnecting and reconnecting the lines repeatedly a possible bad thing and to be saved for parts replacement? or is it all pumped into the calipers already anyway?
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