I need some brake help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

muckyp · 01-20-2011, 01:04 AM

Let me first say that this truck has been sitting for several years now. The master cylinder, brake lines, calipers and all brake components were new (well actually they were installed new by the PO, but had been sitting for several years). So the problem is I can't get the brakes bled. I bench bled the master cylinder and reinstalled it on the truck and attempted to begin bleeding at the right rear wheel with one of the mighty vac brake bleeders. I got nothing!
So I then began reading on here about brake problems. I read one about the lines being clogged so I disconnected the brake lines and blew air threw them to confirm that they were clear and they were.
Can anyone suggest where my problem might be? Does it sound like the proportioning valve is bad?

matthew20061 · 01-20-2011, 04:05 AM

Sounds like you have a good start with bench bleeding the master so that is checked off the list. First are you getting any fluid flow past the proportioning valve? Usually prop valves don't go bad, but the one on my truck ended up having issues. If you aren't getting fluid flow past it then try resetting the proportioning valve. If you are getting fluid flow all the way back to the rear brake wheel cylinders then the wheel cylinders are probably bad if you can't get them to bleed. At least that has been my experience, also if the system has been dry for a couple of years its definitely possible for those new parts to go bad.

cdowns · 01-20-2011, 06:13 AM

theres a pin on proportioning valve that needs to b clamped in place to properly bleed brakes // should start at brake furthest away from master cyl which is the left rear brake

Wrenchbender Ret · 01-20-2011, 11:32 AM

Pull the bleeder valve out & clean it good. Poke a wire in the hole in the wheel cyl. with the valve out. Sometimes they get blocked by crud.

muckyp · 01-20-2011, 07:41 PM

I do not believe there is fluid past the prop valve as I took the line loose just below it and blew air through to the rear wheels. About the valve, is the pin the little green pin or the silver part that surrounds it?
Posted via Mobile Device

muckyp · 01-21-2011, 10:49 PM

So is it safe to assume that if I cannot get air through the rear port on the prop valve that there is something wrong with it?
Posted via Mobile Device

01-20-2011, 01:04 AM	#1
muckyp Registered User Join Date: Mar 2001 Location: Forney, Texas Posts: 290	I need some brake help Let me first say that this truck has been sitting for several years now. The master cylinder, brake lines, calipers and all brake components were new (well actually they were installed new by the PO, but had been sitting for several years). So the problem is I can't get the brakes bled. I bench bled the master cylinder and reinstalled it on the truck and attempted to begin bleeding at the right rear wheel with one of the mighty vac brake bleeders. I got nothing! So I then began reading on here about brake problems. I read one about the lines being clogged so I disconnected the brake lines and blew air threw them to confirm that they were clear and they were. Can anyone suggest where my problem might be? Does it sound like the proportioning valve is bad? __________________ 70 SWB 454/TH400

01-20-2011, 04:05 AM	#2
matthew20061 69' Chevy Stepside Join Date: Mar 2008 Location: Anchorage, Ak Posts: 526	Re: I need some brake help Sounds like you have a good start with bench bleeding the master so that is checked off the list. First are you getting any fluid flow past the proportioning valve? Usually prop valves don't go bad, but the one on my truck ended up having issues. If you aren't getting fluid flow past it then try resetting the proportioning valve. If you are getting fluid flow all the way back to the rear brake wheel cylinders then the wheel cylinders are probably bad if you can't get them to bleed. At least that has been my experience, also if the system has been dry for a couple of years its definitely possible for those new parts to go bad. __________________ -Matthew -69' Chevy Custom/10 Shortbed Stepside 2WD "Copperhead" - Restored, 6.0L LQ9 Built. L92 Heads and LS3 Intake with Comp Cam 223/231 .610/.617 112 LSA, 4L60E with Shift Kit and Circle-D 3200 Stall Converter ~Build Thread -1957 Chevy BelAir 2 Door Post Sedan, Full Frame off Restoration done myself - 6.0L with T56 six speed -1957 Chevy BelAir 2 Door Post Sedan - Nearly rust free AK car, Project in the waiting -2003' Chevy Silverado SS AWD 6.0L! - Daily Driver

01-20-2011, 06:13 AM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: I need some brake help theres a pin on proportioning valve that needs to b clamped in place to properly bleed brakes // should start at brake furthest away from master cyl which is the left rear brake __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

01-20-2011, 11:32 AM	#4
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,228	Re: I need some brake help Pull the bleeder valve out & clean it good. Poke a wire in the hole in the wheel cyl. with the valve out. Sometimes they get blocked by crud.

01-20-2011, 07:41 PM	#5
muckyp Registered User Join Date: Mar 2001 Location: Forney, Texas Posts: 290	Re: I need some brake help I do not believe there is fluid past the prop valve as I took the line loose just below it and blew air through to the rear wheels. About the valve, is the pin the little green pin or the silver part that surrounds it? Posted via Mobile Device __________________ 70 SWB 454/TH400

01-21-2011, 10:49 PM	#6
muckyp Registered User Join Date: Mar 2001 Location: Forney, Texas Posts: 290	Re: I need some brake help So is it safe to assume that if I cannot get air through the rear port on the prop valve that there is something wrong with it? Posted via Mobile Device __________________ 70 SWB 454/TH400

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