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Old 07-21-2018, 07:57 PM   #1
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69heavychevy's Avatar
Join Date: Jan 2007
Location: Garland,TX
Posts: 429
Aftermarket proportioning valve leaking

I replaced my old proportioning valve about 6 months ago with an aftermarket unit. The other day while driving I noticed my brake pedal was getting a little mushy. Popped the hood and saw brake fluid all over the frame crossbrace where the valve bolts too.
Leak was coming from the tiny whole that's on the fitting leading to the rear brakes.
My question is whether this was caused by abnormal pressure in my braking system, maybe some sort of restriction in the rear brakes. I did a complete overhaul on my front and rear brakes last year.
I'm also running hydroboost so I don't know if that could also be an issue?
Or maybe it just a defective unit? I bought from CPP if that makes a difference.
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80 C10 SWB Step Side - 350 w/ vortec heads, TH350, 12-bolt 3.73
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Old 07-21-2018, 09:26 PM   #2
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Join Date: Feb 2016
Location: Hebron
Posts: 865
Re: Aftermarket proportioning valve leaking

I've gone thru these CPP valves many times, and yes they do leak. BUT, if you tell CPP of this issue, I believe they still build a rebuild kit you can do yourself. it's been years that I did this and they did sell one, they just don't let everyone know about the kit. (another fine product from overseas)
1940 Ford Dlx Coupe
1969 Mach1
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Old 07-23-2018, 08:51 PM   #3
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Join Date: Jul 2000
Location: Justin, TX
Posts: 2,218
Re: Aftermarket proportioning valve leaking

Call CPP. They'll tell you they've never heard of the problem before, and will somehow blame it on you. Designed in CA, made cheaply in China.
82 C10 Custom Deluxe SWB -- original paint, 355/TH350, Vortec heads, GM RamJet 350 roller cam.
69 C10 LWB -- Bought in 1989, now my son's.
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
Member here for 20 years! This is the very first car/truck Internet forum I joined.
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Old 09-14-2019, 09:17 PM   #4
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Location: san bernardino ca
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Re: Aftermarket proportioning valve leaking

How did you fix the problem?
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