91 Chevy Truck Front Brake problem...Need help bad!

I started driving this truck about a year ago & it pulled to the left when braking. I figured it needed new pads so about three months ago I changed the pads. The driver side went well but when I went to push
the brake piston in on the passenger side, it was very hard. I changed the pads and it seeemed a little better however later it started to stick or after braking it would pull to the right as though the passenger side brake was sticking. I bought a new caliper thinking the piston was stuck, and replaced the passenger side. The pads were worn very much. I didn't have new pads so I put it back together and it did the same thing-pulling to the right! So this weekend I bought new pads and a master cylinder as well and replaced the pads on both sides and the master cylinder. It was still hard to press the piston on the passnger side without opening the bleeder. I've never had a brake caliper that wouldn't press in. Is there a check valve in there somewhere? The lines to the front brakes come from the master cylinder, through a block, then to a "T", then to each brake. I have clean fluid in there and I can't figure this out. I just got off the road and my brakes were puling hard to the right and I could smell my brakes. Please help me on this! Thanks
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snipped-for-privacy@Datt.s wrote:

The hose layers sometimes separate on the inside and act as check valves.
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This was the problem:

The brake hose from the caliper to the metal line.
A piece of rubber inside the the hose was acting as a check valve and got worse as it heated up. Paul nailed it. I've seen them crack and deteriorate on the outside but I didn't think about it acting as a check valve. Even if it is restricted severely it would still release the pressure but this was different. All day long it worked perfectly. I'm going to replace the driver side as soon as I can.
Thanks again for all the help from all of you...
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There are a few of things to be very wary of: (1) Never never never replace one side of pads unless you replace the other. (2) If you are going to rebuild one caliper,rebuild the other. You can buy new calipers for both sides if you wish, but the rebuild is often very simple. (3) If you have continued pulling problems, replace the hoses on both sides. (4) Flush the system in accordance with the norms for what you have, and do it correctly... ABS, etc...dont guess...do it right.
After all this, if you have problems, let us know.
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On Mon, 03 Aug 2009 18:16:28 -0500, snipped-for-privacy@Datt.s wrote:
Thanks for the help. I suspected something acting as a check valve and its only occurring to the right side. So it could be the flex or rubber hose section blocking the flow back?

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wrote:

Don't think in terms of flowback - think in terms of pressure and no/less pressure. There is no flowback in a brake system.
--

-Mike-
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I think he is thinking in terms of fluid flowing out of the master cylinder upon application of the brake,and back toward the master cylinder upon release of the brake...And it does do that.
If you disagree, just state your point. I might have misunderstood your perspective.
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Yes I did mean flow back towards the master cylinder or in other words release the pressure applied to the brake cylinder. Well to update the story, I just replaced the brake hose on the side in question and it seems ok but tomorrow will tell. I'm in communications and we are a small company but busy as hell so I don't have a lot of extra time. There may be a thermal element involved as well, it seems to do it on hot days but it may just be the amount of useage. You guys are great help and thanks very much, I'll update later. I'm also anxious to cut the old hose open to see what it looks like (If that solved the problem) Thanks again...

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wrote:

Im glad you got it working. Consider that if the brake hose on the passenger side were defective, the other one might be degrading as well. You might want to replace the other as preventative maintenance when you have a moment.
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No - I don't really disagree. Subtle differences become important times though, and that's why I stated to think about it in terms of pressure variances rather than flowback. It's the difference in pressure that makes the braking level, and he had posted that he suspected a checkvalve or something similar restricting flowback. He'd be a long time looking for a checkvalve in a brake line.
--

-Mike-
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You got that right! An intentional checkvalve, at any rate.
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snipped-for-privacy@Datt.s wrote:

Bad rubber line from the frame to the caliper.
--
Steve W.

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wrote:

This was the problem:

A piece of rubber inside the the hose was acting as a check valve and got worse as it heated up. I've seen them crack and deteriorate on the outside but I didn't think about it acting as a check valve. Even if it is restricted severely it would still release the pressure but this was different. All day long it worked perfectly. I'm going to replace the driver side as soon as I can.
Thanks again for all the help from all of you...
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