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97 K2500 7.4LTR Suburban with factory trailer package.
The "O" ring between the Master cylinder and the brake manifold, and the gasket between the brake manifold and the pedal assembly are leaking (8-9 drops a week). I replaced the Master cylinder and manifold last year for $800. Every GM dealer I've talked to tells me they dont sell the "O" rings or gaskets separately. Anyone got a good source for the parts?

Tim
 

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Is that a hydro-boost assist?
I actually had that problem before. I disassembled the booster to see if the o-ring was replacable, and it's a flat wide ring. I've got a store house of o-rings but nothing like that one. I cleaned it up, and reassembled it figuring I'd get to it another time, and it actually hasn't leaked since.

So I'm not really sure if it was because the bolts on the booster were loose, or cleaning the o-rings helped it. all I know is that I no longer see a leak run down the interior of my driver's side foot well behind the brake pedal.
 

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It doesnt have a vacuum booster, (non assist system) but the "O" ring sounds the same. My neighbor gave me one he took off of a wreck at his work to use for reference. I havent been able to match it yet. A few hydraulic shops I talked to offered to repair the truck for anywhere from $300 to $800. Now I'll admit I'm not the worlds brightest, but I figure if I can rebuild this truck from the ground up then I can certainly change an "O" ring and bleed the brake system, and thats got to be cheaper than $300. So the search is still on for parts.
 

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I'm kind of at a loss as to where you are talking about. Could you post a picture of the area where the leak is to give me a better idea?
 

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Did you by chance try your local hardware store. Mine has 2 or 3 boxes of them. With every size and shape.
 

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I'm kind of at a loss as to where you are talking about. Could you post a picture of the area where the leak is to give me a better idea?
tbplus10 doesn't have the booster, but this pic will give you an idea of where the leak is.
 

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In my limited experience, if it's leaking there, you need to either rebuild or replace the master cylinder. I know that's already been done, but I can't imagine what else would cause the leak besides a bad seal in the master cylinder.
 

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Discussion Starter #9
tbplus10 doesn't have the booster, but this pic will give you an idea of where the leak is.
Yep thats where the leak is.

With GM non-assist systems (2500 with factory trailer package, and 3500 trucks) there's a plunger running through this area, its a "wet" area that has fluid running through to a brake manifold thats between the master cylinder and the firewall.
On a Hydro-assist system this would mean time to rebuild due to internal seal leaks.
I'll have to get a picture on Monday.
 
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