Really need some HELP with BRAKES!!
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Joined: Mar 2007
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it happens. take it back and say its faulty get them to give you another then retry it. on big trucks i find sometimes tapping on the calipers gets trapped air out. id do that and replace all the rubber brake lines. that will insure they are new which is never a bad thing. id check the wheel cylinders again and make sure they arent leaking as well. if that doesnt work well looks like its time to replace calipers and or lines. its leaking somewhere if the other stuff doesnt work.
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Lead Driver
Joined: Dec 2003
Posts: 5,250
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so do you think its a bad mc? I mean, with the rear tires in the air and running in 2nd gear at idle, stepping on the brake should have put some strain on the motor. It didnt though. We have not been losing any fluid.
What size of plugs are needed to test the mc? What else could it be. We bypassed the abs and everything looks nice and tight.
What size of plugs are needed to test the mc? What else could it be. We bypassed the abs and everything looks nice and tight.
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Lead Driver
Joined: Dec 2003
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vacuum and it check out found. based on info I saw on another post, I think we have found the problem. Napa gave us the p/n 47-39634 mc, which according to their website has a 1-1/16 bore. We are going to swap it out for the p/n 47-39635 mc with the 1-1/8 bore. Hopefully, that's the problem.
Lead Driver
Joined: Nov 2003
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From: Campbell River, B.C.
Originally Posted by empiretc
vacuum and it check out found. based on info I saw on another post, I think we have found the problem. Napa gave us the p/n 47-39634 mc, which according to their website has a 1-1/16 bore. We are going to swap it out for the p/n 47-39635 mc with the 1-1/8 bore. Hopefully, that's the problem.
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Post Fiend
Joined: Nov 2003
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From: Nutter Fort, WV
Many times when the master cylinder has filings in it, they cut up the internal seals in the master cylinder.
Fluid will bypass the piston seals, but you will never lose a drop of fluid.
Pedal goes to the floor.
You have brakes till the pedal reaches the end of the stroke.
I have had three or four that I have changed that the new master cylinder was worse than the old one.
Fluid will bypass the piston seals, but you will never lose a drop of fluid.
Pedal goes to the floor.
You have brakes till the pedal reaches the end of the stroke.
I have had three or four that I have changed that the new master cylinder was worse than the old one.
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Lead Driver
Joined: Dec 2003
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I researched this, and found (according to chilton and the repair manuals found in my sig) that the truck mc is supposed to be 1-1/8. This is why I cannot believe that napa, oh-rye-lees, and several other places put out these with the 1-1/16 bore. There is no way they can work right.
We are installing it in the morning and I will post back and let you all know what happens.
We are installing it in the morning and I will post back and let you all know what happens.
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