I have a weird brake problem. When the engine is off, i have a nice firm pedal with very little travel. As soon as i turn the engine on, the pedal sinks and i have no brakes. Ive replaced master cylinder and checked many times for leaks and there are none. Anyone have any ideas?
Brake Problem
- Thread starter snowmangaggift
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snowmangaggift said:
I had some similar issues with my ride recently......viewtopic.php?f=19&t=37113
Just curious...did you bench bleed the master cylinder? This has to be done or you will introduce lots of air into the system. Also, you may have a bad brake booster or the vacuum line to the booster may be cracked/leaking. Why did you replace the master cylinder? If it was leaking, it may have ruined the booster. If you did bench bleed the M/C, I would gravity bleed the system starting at the right rear and working around to the left front, one wheel at a time. You will need a least a quart of new fluid to do this and dont let the M/C get too low or you will have to start all over again....You definately have air in the system...not likey that the booster is bad...but check out the vacuum line going to it.
Yeah, I bench bled the master cylinder with no issues. I replaced it due to the visible brake fluid leaking down the front of the booster. Also, I have bled and bled both callipers and wheel cylinders and I am certain there is no air in the lines. Although, now that you mention is the line from the brake booster to the back of the carb has this funny valve looking thing in the middle of the line. There is the valve on the booster which is normal, but then it looks like the line was cut in half and this weird looking thing tossed in. Any idea what this is?bill said:
That funny looking thing is a filter for the vacuum line going into the booster. It should allow air flow in both directions. Replace it if you find it clogged up. It takes a lot of bleeding to get air bubbles from the M/C to the calipers/wheel cylinders. I used over a quart of fluid bleeding my lines, but I found air in them after a while, at thats why I had no pedal pressure/ stuck valve.snowmangaggift said:
You could have a bad master cyl. Remove the 2 lines frome the master and install the 2 plugs that came with it for bleeding purposes. Try the pedel like that, should not move at all, if it does its bypassing on the master. Is there a good amount of fluid pressure while bleeding four wheels?
make sure your rear drums are tight i had the same trouble and i backed out the shoes and every thing was fixed
Awesome, I will try all these suggestions thanks so much. Havnt had time to work on the brakes lately, just finished swapping in my new engine 😀
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