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1976 C10 - No Brake Fluid to Front Driver Side


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beems
Novice

Apr 20, 2017, 11:36 AM

Post #1 of 20 (393 views)
1976 C10 - No Brake Fluid to Front Driver Side Sign In

Vehicle: 1976 C10 RWD Pickup
Brake System: Rear Drum, Front Disk

So in learning to do some basic mechanical stuff on my old, inherited truck, I've come across a brake problem I don't know how to troubleshoot. The truck has always pulled to the right when I braked, so the problem has likely been going on for a long time.

The rear drums have had new hardware kits and hardware cylinders, and the front has new calipers and pads.

The brake system was bleed successfully until I got to the last wheel - the front driver side. I have no fluid at that wheel, and the rest of the system is now pretty "tight" after bleeding (the brakes are set a little snug against rotors/drums after the bleeding of the first 3 brakes).

I'm assuming the problem is with the proportioning valve because my father said that the brake light was on so he unplugged the indicator from the proportioning valve. This leads to the conclusion that the proportioning valve has been tripped for years or even decades for all we know. Am I on the right track, or where should I start to troubleshoot this? If it is the proportioning valve, is there any way to "reset" it or do I need to buy a new one?

Thanks in advance,
Beems


Hammer Time
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Apr 20, 2017, 12:00 PM

Post #2 of 20 (388 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

I don't know how you got to proportioning valve but it sounds like a bad rubber flex hose. I would replace both front and in the process, make sure the caliper pistons and slides are free.



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beems
Novice

Apr 20, 2017, 1:39 PM

Post #3 of 20 (382 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

Sorry for my ignorance, but if the proportioning valve has tripped won't it cause the "Brake" light on the dash to light up? The sensor is unplugged from the proportioning valve right now so of course right now the dash light isn't on.


Hammer Time
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Apr 20, 2017, 1:51 PM

Post #4 of 20 (377 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

I've been in this business 50 years and I think in that time I have changed one proportioning valve.

If your brake light is on, that means there is an imbalance in the 2 braking systems. You need to find out where the air is in the system. A proprtioning valve won't give you the symptoms you refer to. Check what I stated the first time.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on Apr 20, 2017, 1:51 PM)


kev2
Veteran
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Apr 20, 2017, 2:09 PM

Post #5 of 20 (369 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

this is a combination valve AKA proportioning - it may need to reset, recenter the valve after it has 'latched' either forward or rearward.
Often the switch is removed to aid valve (spool) movement - try google resetting combination or proportioning valves - pictures will help you ID which exact model.


Hammer Time
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Apr 20, 2017, 2:13 PM

Post #6 of 20 (366 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

On this truck that valve separates the front from the rear, not left to right so I don't see how it can possibly cause pulling when braking or no fluid to one wheel.



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Tom Greenleaf
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Apr 20, 2017, 2:18 PM

Post #7 of 20 (362 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

Flex hose - no waste not to anyway, both as HT said earlier,


T



beems
Novice

Apr 20, 2017, 2:22 PM

Post #8 of 20 (356 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

Thanks everyone - I'll go snag the front flexible brake hoses.

And Hammer Time, you gotta' relax man, you're going to give yourself an aneurysm. You just said "I don't know how you got to proportioning valve" so I responded. I wasn't in any way saying you were wrong, so please take it easy.


Tom Greenleaf
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Apr 20, 2017, 2:42 PM

Post #9 of 20 (354 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

Everyone calm down! beems: It's not the proportioning valve - I'm near sure because they don't fail at all usually and can't really that way.


Pinched line doesn't usually even stop flow. A bleeder could that you can clean out or just get a new one. Learn to love this truck there isn't much simpler for much out there as this vehicle goes, parts available and not costly,


T



Hammer Time
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Apr 20, 2017, 2:47 PM

Post #10 of 20 (350 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

I wasn't even responding to you. I was more responding to Kev who seemed to be pushing the proportioning valve idea.



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kev2
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Apr 20, 2017, 3:47 PM

Post #11 of 20 (341 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

WHOA - Don't shoot the messenger I also think flex line - comment was to have poster look into valve operation - .
There are several different types, and as I said 1976 is not fresh in my mind. learn before changing it was my thought


Tom Greenleaf
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Apr 21, 2017, 6:46 AM

Post #12 of 20 (321 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

Still, please calm down. It is fresh in my mind though - still have impossible to find flare nuts that fit into the "combination valve" is what it's called as it double to set off (light up) brake warning light.
They can get stuck when whole FRONT or WHOLE real has a total pressure loss almost always a rusted out line. If you keep driving it then it might stick blocks off failed system of the two - front and rear only not left and right.
If both of a system - the fix if you live 100 years to have that problem is open the stuck end when fixed right at the master cylinder even pushes it back and then self centers. This isn't the issue so can forget that.


Why picking on one wheel: Can only be a few things......... 1st bad flex hose. 2nd knowing the bleeder works and is clear - take it out and clean it with drill bits. 3rd is a brake line was smashed - any way from a rock, hard hit by mistake by something in it's life?


The rarer other is the caliper isn't any good or pins all screwed up. They rebuild these again and again, rig up a bleeder from a lousy core with a brass insert or who knows? Not all come out well but look nice in the box.


The real disaster hasn't been mentioned is if this was contaminated by something other than brake fluid all rubber parts could fail in assorted ways. Clue would be the rubber seal inside the cap of the reservoir would show swelling if an OIL was introduced. If so make this another whole thread as that would be a serious problem with assorted first symptoms then an involved fix,


Tom



(This post was edited by Tom Greenleaf on Apr 21, 2017, 6:49 AM)


beems
Novice

Apr 21, 2017, 11:38 AM

Post #13 of 20 (307 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

Tom, thanks for the detailed tips.

The bleeder shouldn't be the issue because as new calipers were installed I removed everything up to and including the banjo bolt. So at that point, effectively right off the flex line, I have no fluid flow. When I pulled it off the caliper fluid flowed, but apparently only what was in the line. After that was gone I get nothing even when pressing the brakes hard. Since we know the problem exists above that, we can also rule out the caliper. I'll grab a set of flex hoses on my way home (even though one is good, they're only about $14/each so I'll just swap them both. Once I get those swapped I'll be sure to look around for a smashed hard line.

Notably, the rubber seals in the reservoir caps look good to my untrained eye (still flexible and don't appear swollen).

Thanks again for all the support and tips everyone. I'll be sure to swing back by here as I go through this truck piece by piece.


Tom Greenleaf
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Apr 21, 2017, 1:21 PM

Post #14 of 20 (301 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

Ya - just do them but do yourself a favor and put some PB penetrating oil on the frame end of the hose now AND especially where metal line goes into flare nut right there. If that line that loves to twist up busts off it's a harder line to make up new so try hard not to ruin it.


Do know the metal lines you make yourself with raw line or straight line with ends already on that might not be yours so you bend and flare ends yourself. That stuff isn't sold new ready to just put on,


T



beems
Novice

May 11, 2017, 10:49 AM

Post #15 of 20 (244 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

Yeah, bad news: despite soaking that bad boy in penetrating oil (not WD40 mind you) for a few hours before getting around to it, I still rounded off the copper nut on the end of the hard line where it meets the hose.

So apparently I get to bend a new line! Yay? Well, I guess I'll learn two lessons:
1) Don't round off the nuts
2) How to bend a brake line


Tom Greenleaf
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May 11, 2017, 12:40 PM

Post #16 of 20 (235 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

It's not copper in fact if it was probably wouldn't do that.


I expected that - you use heat - glowing red-white hot can do some.


It happened so not the issue now: Are you going to make up that line or have that done?


You can - Tools for cutting new line, flaring it with new flare nut and bending it without kinking it to just the right length. You may not need to go all the way back just to an area that's perfect and install a union.


I can and have written total novels here on how to for what is really pretty basic once you know how. At this point with some tools that will add up and knowing where you can do what plus have it in place so it doesn't rub I'd just send it out and expect about $200 bucks for that line made up and bleed the vehicle. It quite likely is really worth it to you as now you plain don't have brakes worth a damn - couldn't,


T



beems
Novice

May 11, 2017, 2:00 PM

Post #17 of 20 (223 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

I stopped into the auto parts store, and if I bring the old line in they have lines that are the right lengths, with the right flarings and the right nuts. All I would have to do is bend it, and they will rent me the benders. So about $10 for the line and another $7 for rental of the bender - seems like it's worth a shot at least for that price. Otherwise, if I screw that up, I found a full set of the (4) pre-bent lines for the front wheels for $110 (not including shipping, which I'm sure will be expensive). And surely replacing the existing lines with pre-bent lines (subtract from finagling them into place) should be pretty "plug and play" I assume.http://www.lmctruck.com/...c/full.aspx?Page=151


Hammer Time
Ultimate Carjunky / Moderator
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May 11, 2017, 2:32 PM

Post #18 of 20 (210 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

They have assorted pre-made lengths, not necessarily the length required for your line and not necessarily the correct fittings.
You have to determine the length you require and match that up with one of their pre-made lines. If the fittings are different, you have to cut the line to change the fitting and then double flare the end.

Making these lines are not a real simple job.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
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May 11, 2017, 2:33 PM

Post #19 of 20 (207 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

I need to take the link out, not really allowed. Just use the content not the spot it came from.


Here's the problem spots even if they sell pre-bent lines: They are held in place by assorted holders, metal with a bolt that will also break if line broke. Now what? They make stuff to hole lines so they stay in place, don't vibrate or rub.


I don't use a bending tool most of the time rather can do if practice with rounded wood frequently and cut off a pre made whole very long line not costly but has the flare nuts you'll need.


If you can take out old one cut to the right spot or all the way. Flare nut if you go all the way it goes may use a different flare nut so re-use that one or take it with you to match it for a new one at a parts store that stocks that stuff. This isn't hardware store stuff it's automotive grade stuff. No faking it with compression fittings and pure copper line both not legal or safe.


Beware of things like YouTube like demonstrations of how to do this. 1/2 of that stuff will not be your exact situation or could be all wrong.


I said it was relatively easy but I've also done tons of this and have soft plastic called wire holders to bolt to frames if need be in same spots OE ones were.


Not costly but takes thought and time to do this right. With old line make up what you can on workbench or whatever it takes first.


Like a lot of things if a first for you having someone who really knows it specifically a tech in the trade that's done it or better a lot of it show you how. Real learning how not to mess it up which bet we've all done and started over you get that hands on experience on how to avoid that.


Be realistic: How many times are you personally going to make up brake line, fuel line, transmission cooling line, evaporative emission line too? If not much pay for it and forget it but the right tech and be done with this.


Many things are NOT worth the tools or learning for the one time unless you are driven to know how it's done where $$ doesn't matter so much as the satisfaction you did it and it was perfect.


Hey - when vehicles are made new those lines are already to go. I didn't know they were available pre-done which I'm worried about. Some were installed when new when frame only was there - nothing in the way and now have to make unions as you can't route the one whole section end to end just right.


Trying to save you the time unless you insist and understand wanting to both learn it and see it done right.


I just can't do all that with these lengthy notes - almost books on how.


For now just one last warning. When you thread in new stuff to the matching part do the final tiny bend so you can thread it in by fingers no tools so you don't cross up threads. One or more full turn by hand then you can put a flare nut wrench on it or open possibly another whole mess to deal with,


Tom



Hammer Time
Ultimate Carjunky / Moderator
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May 11, 2017, 3:28 PM

Post #20 of 20 (198 views)
Re: 1976 C10 - No Brake Fluid to Front Driver Side Sign In

Try to take out the old one in one piece without bending it so you can use it as a template to bend the new one.

I've done a lot of this and these pliers are the very best tool for bending these lines





~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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