New Master Cylinder won't work??? Why?
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Joined: Apr 2002
Posts: 91
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From: Asheville NC
New Master Cylinder won't work??? Why?
I just redid my entire brake system today and when I went to bleed it the master cylinder keeps blowing air out of a small hole on the bottom right by the mounting screws and it wont push any fluid through the lines. Does anyone know what I'm doing wrong? :confused:
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Re: New Master Cylinder won't work??? Why? (JoeMacgruder)
You did take those plastic caps off didn't you? :jester There is fluid in both the reservoirs aren't there? :crazy:
If the m/c isn't pushing fluid out the outlets with the bleeders closed (or out the bleeders with the outlets plugged) and there is fluid in both reservoirs then something is plugging the m/c internally...just take it back for a replacement. It's strange to see both outlets plugged though...usually it's just the front or back. The rebuilder could have been chewing gum and coughed...and couldn't find where the gum went. :rolleyes:
If the m/c isn't pushing fluid out the outlets with the bleeders closed (or out the bleeders with the outlets plugged) and there is fluid in both reservoirs then something is plugging the m/c internally...just take it back for a replacement. It's strange to see both outlets plugged though...usually it's just the front or back. The rebuilder could have been chewing gum and coughed...and couldn't find where the gum went. :rolleyes:
Pro
Joined: Jul 2000
Posts: 654
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From: Now Frozen in Michigan
Re: New Master Cylinder won't work??? Why? (JoeMacgruder)
Joe-
Bench bleeding the MC will purge the internal cylinder and passages of air prior to install. This is done by typically mounting the MC in a vise and installing a pair of flex lines that attach to the outlets and are looped back into the MC reservoirs. Add brake fluid to the reservoirs and with a suitable socket extension or punch 'cycle' the MC piston until air bubbles dissappear from the lines. This 'primes' the MC and assures that no additional air will be introduced into the system.
I personally disassemble new/rebuilt MC's to clean and inspect. Checking the condition of the seals and MC bore. It's surprising what you'll find sometimes in terms of debris and so called new parts. Have seen many bores that are scored or pitted. It doesn't take long, and to me worth the extra minutes to assure good quality and function. Oh, and don't chew gum while you do this! :lol: Good Luck -Rod :chevy
Bench bleeding the MC will purge the internal cylinder and passages of air prior to install. This is done by typically mounting the MC in a vise and installing a pair of flex lines that attach to the outlets and are looped back into the MC reservoirs. Add brake fluid to the reservoirs and with a suitable socket extension or punch 'cycle' the MC piston until air bubbles dissappear from the lines. This 'primes' the MC and assures that no additional air will be introduced into the system.
I personally disassemble new/rebuilt MC's to clean and inspect. Checking the condition of the seals and MC bore. It's surprising what you'll find sometimes in terms of debris and so called new parts. Have seen many bores that are scored or pitted. It doesn't take long, and to me worth the extra minutes to assure good quality and function. Oh, and don't chew gum while you do this! :lol: Good Luck -Rod :chevy
Melting Slicks
Joined: Mar 2001
Posts: 3,365
Likes: 5
From: Lake Villa IL
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Cruise-In V Veteran
St. Jude Contributor
Re: New Master Cylinder won't work??? Why? (JoeMacgruder)
Make sure when you bench bleed, the caps on the holes are tight. If they aren't, you'll suck in air.
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: New Master Cylinder won't work??? Why? (ROD NOCK)
In MY opinion ... NEVER use a rebuilt master cylinder EVER.... Most are already pitted and fail in a short time. Of course the ones that are custom rebuilt with stainlees sleeves are fine, but not over the counter rebuilds... :U :U :U :U :U
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