Aftermarket proportioning valve leaking - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69heavychevy · 07-21-2018, 07:57 PM

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.

my56chevytruck · 07-21-2018, 09:26 PM

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)

**MikeB** · 07-23-2018, 08:51 PM

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.

rvrfoot · 09-14-2019, 09:17 PM

How did you fix the problem?

07-21-2018, 07:57 PM	#1
69heavychevy Registered User Join Date: Jan 2007 Location: Garland,TX Posts: 431	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. Attached Images __________________ 80 C10 SWB Step Side - 350 w/ vortec heads, TH350, 12-bolt 3.73

07-21-2018, 09:26 PM	#2
my56chevytruck Registered User Join Date: Feb 2016 Location: Hebron Posts: 1,153	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) __________________ RUBBER DOWN AND HIT THE ROAD!!! 1940 Ford Dlx Coupe 1969 Mach1

07-23-2018, 08:51 PM	#3
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,597	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. __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. 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 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

09-14-2019, 09:17 PM	#4
rvrfoot Registered User Join Date: Oct 2016 Location: san bernardino ca Posts: 1,611	Re: Aftermarket proportioning valve leaking How did you fix the problem?



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