Brake problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ThomasTedder · 01-15-2011, 07:12 PM

I got this 82 C20 after it was sitting in a field since 1997. The brakes on the right side both worked and the one on the left side weren't. I put on a new master cylinder, left front caliper, and left rear wheel cylinder. The left rear brake bled fine, but I cannot bleed the left front brake. I have a vacuum bleeder and I still cannot get any fluid through the left front. I separated the hose from the new caliper and I cannot suck fluid through the hose either. Pushing the brake will not squirt any fluid out of the hose. I know the master cylinder isn't bad, because the right front brake works. I cannot remove the brake line without destroying it so I need to know if the Combination valve can cause a problem like this before I assume the hose is plugged. I read in the book that the combo valve won't engage the front brakes until there is enough pressure on the back brakes, but I know the back brakes work (they will squall the tires). The book also says to depress a pin on the combo valve when bleeding. I had someone press the brakes while I held the pin. I was watching the dangling hose and nothing still comes out. All that happens is the pin stabs my finger. I even used a steel wrench to hold the pin and still nothing will come out of the hose.

So am I looking at a bad combination valve or a plugged hose?

Here's a pic. The camo is what sold me on it.

**old Rusty C10** · 01-15-2011, 11:12 PM

if you cant remove the brake line without destroying it im betting its shot

ThomasTedder · 01-15-2011, 11:34 PM

Quote:

Originally Posted by old Rusty C10

if you cant remove the brake line without destroying it im betting its shot

It's not that bad looking, it's just that the shoulders are so damn narrow and I can't really get a wrench on it properly. I just know I'll round off the shoulders if I try to remove it. Basically, I'm poor and I'd like to know that it's clogged before I replace it.

James McClure · 01-16-2011, 09:19 AM

Tom. Combination valve will not block left to right fluid flow. It will control front to rear, so if the rears are working and the right front is working the combination valve is OK. Check the line (steel one) from the combination valve to the left front hose connection. If it's not damaged, replace the hose to the caliper. jim

ThomasTedder · 01-16-2011, 11:21 AM

Quote:

Originally Posted by James McClure

Tom. Combination valve will not block left to right fluid flow. It will control front to rear, so if the rears are working and the right front is working the combination valve is OK. Check the line (steel one) from the combination valve to the left front hose connection. If it's not damaged, replace the hose to the caliper. jim

Thanks Jim
Posted via Mobile Device

lilpoindexter · 01-16-2011, 11:50 PM

Try changing just the hose...should be relatively easy, spray PB blaster on the nut an hour ahead of time.

ThomasTedder · 01-17-2011, 11:14 AM

Alright, I'm going to replace the hose when I get some money.

silvereagle07 · 01-17-2011, 11:58 AM

When I replace the hoses on my c10 last summer , I have to remove the combination valve to get the left front hose off. It was trying to strip so I remove them both and locked it in a vice. With a little persuasion, I was able to remove the brake hose. The hoses are really bad about collapsing with some age on them. They are cheap and I would replace both sides. Good luck.

rfmaster · 01-17-2011, 12:22 PM

I had nearly identical problem with brakes on my '75 few month back. The culprit was a collapsed rubber hose (<$15) between caliper and hard line (front right). To remove flex hose use plenty of WD-40 or rust-break spay to loosen up connection between flex hose and hard line. To disconnect flex hose I used flared crow foot to prevent rounding off shoulders on the flare nut (IRC 3/8 or 7/16"). I replaced all brake rubber hoses - they are cheap and after 36 years of service rubber collapses.

//RF

ThomasTedder · 01-17-2011, 01:14 PM

I'm glad to know it's not the combo valve. I think I'm going to soak it in PB Blaster and cut the hose right next to the fitting and put a socket on it (since I don't have to save it).

rfmaster · 01-17-2011, 05:18 PM

Quote:

Originally Posted by ThomasTedder

I'm glad to know it's not the combo valve. I think I'm going to soak it in PB Blaster and cut the hose right next to the fitting and put a socket on it (since I don't have to save it).

The brake line has the male inverted flare (Double /SAE 45 degree Flare) and rubber hose is equipped with corresponding female inverted flare. To uncouple this junction you'll have to turn male side of inverted flare and keep rubber hose from rotating. Turning from rubber hose side will twist (and break ) brake line - not a good thing at all!

http://www.fedhillusa.com/webnuts/common%20flares6.pdf

//RF

ThomasTedder · 01-18-2011, 12:02 AM

Very good info, thanks.
Posted via Mobile Device

ThomasTedder · 01-31-2011, 01:46 AM

UPDATE!

The flexible hose was the problem. Unfortunately, I couldn't get the hard brake line off without rounding off the shoulders. I knew it was going to happen. I just clipped the hard line at both ends with a pair of dykes and put a socket on them. I got 18" of hard line pre-flared with the ends already on for like $6 and bent it to fit. Now, my left front brake works.

01-15-2011, 07:12 PM	#1
ThomasTedder Registered User Join Date: Jan 2011 Location: Post Falls, ID Posts: 16	Brake problem I got this 82 C20 after it was sitting in a field since 1997. The brakes on the right side both worked and the one on the left side weren't. I put on a new master cylinder, left front caliper, and left rear wheel cylinder. The left rear brake bled fine, but I cannot bleed the left front brake. I have a vacuum bleeder and I still cannot get any fluid through the left front. I separated the hose from the new caliper and I cannot suck fluid through the hose either. Pushing the brake will not squirt any fluid out of the hose. I know the master cylinder isn't bad, because the right front brake works. I cannot remove the brake line without destroying it so I need to know if the Combination valve can cause a problem like this before I assume the hose is plugged. I read in the book that the combo valve won't engage the front brakes until there is enough pressure on the back brakes, but I know the back brakes work (they will squall the tires). The book also says to depress a pin on the combo valve when bleeding. I had someone press the brakes while I held the pin. I was watching the dangling hose and nothing still comes out. All that happens is the pin stabs my finger. I even used a steel wrench to hold the pin and still nothing will come out of the hose. So am I looking at a bad combination valve or a plugged hose? Here's a pic. The camo is what sold me on it. Last edited by ThomasTedder; 01-15-2011 at 07:17 PM.

01-15-2011, 11:12 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,310	Re: Brake problem if you cant remove the brake line without destroying it im betting its shot __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

01-16-2011, 09:19 AM	#4
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: Brake problem Tom. Combination valve will not block left to right fluid flow. It will control front to rear, so if the rears are working and the right front is working the combination valve is OK. Check the line (steel one) from the combination valve to the left front hose connection. If it's not damaged, replace the hose to the caliper. jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

01-16-2011, 11:50 PM	#6
lilpoindexter Registered User Join Date: Sep 2010 Location: los angeles Posts: 1,134	Re: Brake problem Try changing just the hose...should be relatively easy, spray PB blaster on the nut an hour ahead of time.

01-17-2011, 11:14 AM	#7
ThomasTedder Registered User Join Date: Jan 2011 Location: Post Falls, ID Posts: 16	Re: Brake problem Alright, I'm going to replace the hose when I get some money.

01-17-2011, 11:58 AM	#8
silvereagle07 Registered User Join Date: Sep 2008 Location: Bailey, NC Posts: 2,462	Re: Brake problem When I replace the hoses on my c10 last summer , I have to remove the combination valve to get the left front hose off. It was trying to strip so I remove them both and locked it in a vice. With a little persuasion, I was able to remove the brake hose. The hoses are really bad about collapsing with some age on them. They are cheap and I would replace both sides. Good luck. __________________ Jeramy '84 GMC project truck '85 Chevy 4X4 SOLD '07 Chevy Trailblazer SS 5th Annual SHPHC Car/Truck Show Pics http://67-72chevytrucks.com/vboard/s...d.php?t=543605 UPDATED PICS! CHECK 'EM OUT

01-17-2011, 12:22 PM	#9
rfmaster Registered User Join Date: Oct 2003 Location: OC CA Posts: 1,374	Re: Brake problem I had nearly identical problem with brakes on my '75 few month back. The culprit was a collapsed rubber hose (<$15) between caliper and hard line (front right). To remove flex hose use plenty of WD-40 or rust-break spay to loosen up connection between flex hose and hard line. To disconnect flex hose I used flared crow foot to prevent rounding off shoulders on the flare nut (IRC 3/8 or 7/16"). I replaced all brake rubber hoses - they are cheap and after 36 years of service rubber collapses. //RF __________________ "The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17) Last edited by rfmaster; 01-17-2011 at 12:25 PM. Reason: add photo

01-17-2011, 01:14 PM	#10
ThomasTedder Registered User Join Date: Jan 2011 Location: Post Falls, ID Posts: 16	Re: Brake problem I'm glad to know it's not the combo valve. I think I'm going to soak it in PB Blaster and cut the hose right next to the fitting and put a socket on it (since I don't have to save it).

01-18-2011, 12:02 AM	#12
ThomasTedder Registered User Join Date: Jan 2011 Location: Post Falls, ID Posts: 16	Re: Brake problem Very good info, thanks. Posted via Mobile Device

01-31-2011, 01:46 AM	#13
ThomasTedder Registered User Join Date: Jan 2011 Location: Post Falls, ID Posts: 16	Re: Brake problem UPDATE! The flexible hose was the problem. Unfortunately, I couldn't get the hard brake line off without rounding off the shoulders. I knew it was going to happen. I just clipped the hard line at both ends with a pair of dykes and put a socket on them. I got 18" of hard line pre-flared with the ends already on for like $6 and bent it to fit. Now, my left front brake works. __________________ 1982 C20



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