Soft brake pedal, after bleeding lines
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Joined: Mar 2009
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Soft brake pedal, after bleeding lines
So close to taking it out of the barn.
All new brake lines, wheel cylinders, and calipers.
Master cyl looks good, but the pedal is still mushy, I can pump it a bit, then I can push it almost to the floor.
Time for a new booster?
Not too pricey, any tricks to replacing booster ?
Weekend off, and the weather is great, I want to go for a ride!
Thank you, C
All new brake lines, wheel cylinders, and calipers.
Master cyl looks good, but the pedal is still mushy, I can pump it a bit, then I can push it almost to the floor.
Time for a new booster?
Not too pricey, any tricks to replacing booster ?
Weekend off, and the weather is great, I want to go for a ride!
Thank you, C
Posting Guru
Joined: Nov 2007
Posts: 2,158
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From: West Texas
sounds like booster. There is a service bulletin on these for just this problem. Don't just go to the parts store and get one, you need to make sure to use the proper part number for the zero loss booster. Or just ask for a 97 booster. I believe they came with it but I'm not 100% positive.
Oh when you bleed them do NOT pump the pedal. Just push down, open bleeder, close bleeder let up. That's it. And don't forget the bleeder on the abs actuator.
Oh when you bleed them do NOT pump the pedal. Just push down, open bleeder, close bleeder let up. That's it. And don't forget the bleeder on the abs actuator.
Posting Guru
Joined: Nov 2007
Posts: 2,158
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From: West Texas
Boosters do cause that on these and it's real common prior to the 97 models. I've never seen the internals of one yet so don't know why but they do it.
Look at the size of your cylinder stamped on the side of it. Make sure the new one is the same size. They are misboxed a lot. The IDI and 94 had a smaller one then newer trucks. Also when you bleed it again do nearest to farthest bleeder and don't forget the abs actuator. No pumping. Just down and up. You aren't supposed to pump any abs systems.
Oh and check those parking brake levers. If they aren't back nearly to the edge of the backing plate when you pull the drum off then you need to fix them. That will cause your problem too. Then adjust the brakes to get a real slight drag on the drums. You should be able to turn the wheel easy but not spin it.
Look at the size of your cylinder stamped on the side of it. Make sure the new one is the same size. They are misboxed a lot. The IDI and 94 had a smaller one then newer trucks. Also when you bleed it again do nearest to farthest bleeder and don't forget the abs actuator. No pumping. Just down and up. You aren't supposed to pump any abs systems.
Oh and check those parking brake levers. If they aren't back nearly to the edge of the backing plate when you pull the drum off then you need to fix them. That will cause your problem too. Then adjust the brakes to get a real slight drag on the drums. You should be able to turn the wheel easy but not spin it.
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Hotshot
Joined: Aug 2006
Posts: 10,764
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If the braking system is hydraulic (& it is ) the assist cannot cause a soft pedal . Air introduced or oil fluid leaking past a seal will cause this ..I have been fixing brake issues for 40 years & have never had to replace a booster that wasn't leaking .When they fail ,the brakes are like manual used to be ...
You are saying that for some reason the vacuum boost on the early OBS systems is different than every vacuum assist on every other vehicle ?...I need to have this explained to me ,due to it makes no sense at all ...
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Hotshot
Joined: Aug 2006
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If you bleed front or rear (doesn't matter which you do first) till they are clear ).. you will be fine ...Again 40 years of bleeding brakes , it makes no difference what you do as long as the air is gone ... OP needs a MC ....
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From: THUNDER BAY
X2 and it needs to be bench bled before put on the truck.
Senior User
Joined: Nov 2006
Posts: 222
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From: Sayreville, NJ
When you have to bleed as many cars and trucks as I do and by myself most of time, this is what works great and fast. Just hook it up, pump it up to about 10 psi and then open up bleeder and close when straight fluid comes out. No starting engine and no pumping brakes. Some cars require just one tap on pedal while under pressure and that get the fluid past abs valve, but most of time it just works on it own.
Universal Bleeder Kit 0250 -- Motive Products Online Store
Of coarse on my big trucks, I want air in the brake lines
Universal Bleeder Kit 0250 -- Motive Products Online Store
Of coarse on my big trucks, I want air in the brake lines