Master cylinder

Tiny
HKFROMNY.
  • MEMBER
  • 2005 CHEVROLET IMPALA
  • 3.4L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
Hey, working on replacing rear brake lines, and cannot trace the lines up to master cylinder. Anyway you can guide me as to which are the rear ports? Will take pictures and stuff.
Wednesday, July 4th, 2018 AT 10:55 AM

17 Replies

Tiny
ASEMASTER6371
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Good afternoon.

The larger lines, the front top and bottom are the fronts. All four lines go to the ABS module and then out to each wheel.

Here are the master cylinder installation instruction you have requested. Here is a guide to help you step by step with instructions in the diagrams below to show you how on your car.

https://youtu.be/WDxvEQrMkBg

and

https://youtu.be/w7gUsj2us0U

and

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.
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Monday, March 8th, 2021 AT 10:51 AM
Tiny
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I think at some point someone did brake lines, all four lines are the same size 3/16", and I do not see any ABS module. Where might this be located? All I can see is the lines, (brake, and fuel ) go down along firewall, and back along the frame work to the rear. So if I am understanding, you say the two ports (top and bottom ) that are closest to firewall will be rear brakes?
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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Do you have a ABS light come on when you turn the key on?

Yes, the rears are the rear section of the master cylinder.

Roy
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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I see nothing as an ABS light when key is turned on, and according to you, if you look at the picture the two lines at rear of master cylinder look new. That is the two new lines that go new all the way back to the rubber lines at tires. So, we are very concerned, and confused as to how we got fluid spitting out of an old line. Is it possible to have an proportioning valve (module) somewhere tucked down by sub-frame, (under engine)? Cannot find anything.
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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The smaller lines in the rear go to the rear wheels. If you do not have ABS then there are metering valves in the lines. One for each line. They will look like a connector connecting the lines. They are usually located back by the rear tires.

Roy
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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Well, I just replaced both lines as your describing, but after putting the last fittings together, had dad press on brake pedal, and fluid gushed out the old section of line, but how? Parts of the old lines being held in place be clips, kind of like spark plug wire keepers. How is fluid coming out of something that has been removed from master cylinder? That is the basis behind me asking about which ports feed the rear brakes. See my puzzle now? I have it hooked up right according to you, unless, at some point someone replaced lines at master cylinder in the wrong order. Cannot figure it any other way.
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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Where do the lines from the master cylinder end?

Roy
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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We ran brand new for both sides from master cylinder back to each tire, only one coupling in middle of each line, no obstructions. Just left the parts of old lines I could not just grab onto and remove.
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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You do not see this unit down low under the cruise control unit?

Roy
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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I see nothing that looks even close to that. We are thinking at some point someone totally removed this module. I have seen where there should be something plugged into something, but there are no wires going to or from any tire.
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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Can you upload some pictures of what you see?

Roy
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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I will be happy to. I have some errands to run, but I will send some just as soon as I get back.
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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Okay, sounds like a plan. I will be on most of the day EST.

Roy
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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I think this video should explain the issue. Not what either of us assumed. I think this proves someone changed stuff earlier on.
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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Okay, the check valves or metering valves are in the master cylinder. The back lines are one front wheel and one back wheel. It is a split diagonal system this means you have right front and left rear applying at the same time and the left front and right rear at the same time. This helps prevent brake pull.

Do not change any position of the lines.

Roy
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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Do not think my last message got sent, but, I am really glad you said that. I was all fired up to switch everything to front, front, rear, rear. I will let you know the final results after our rain storm finishes, lol.
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Monday, March 8th, 2021 AT 10:52 AM
Tiny
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Sounds good.

Roy
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Monday, March 8th, 2021 AT 10:52 AM

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