Advice on: Master cylinder, booster, and calipers (leaks on 76 GMC 1 ton--pictures)

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OldBlueDually

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Hey gents, I was hoping not to spend a ton of money here (I am so far over budget right now I am cringing and not even close to done), but being as how I have NOT worked with squares until this point, maybe you guys can give me some advice.

Advice I am looking for;
1.) Would you use a re-build kit on the master cylinder and booster pump (or send booster in for rebuild)?
a.) If you would buy a kit, where would you buy them (Rock Auto has master cylinder re-build kit, but not for booster pump)
b.) Or could this lead to other problems (or just not work), and buying new makes more sense because you may be money ahead?

2.) How would you correct the leaking issue at the pass side caliper?
a.) Bend the line slightly to clear the drop spindle?

Back story on the problems: 2 weeks back I cleaned up my master cylinder reservoir, the small one in front was fairly clean with some fluid in it, but I cleaned it out (stuffing shop rags in it to get out fluid). The back large one was dried up, had some scaling rust in it, and chunks of old fluid. I cleaned this out also with a few shots of brake cleaner (not down into ports) and some scrubbing with shop rags.

I then stuffed shop rags in both reservoirs and sanded the top of the master cylinder with my flat block hand sander to clean up the lid sealing surface. I then cleaned the rubber seal, and the top cap where the rubber meets that cap. After that I carefully lifted out the rags and then blew compressed air into it (about a foot away) to get any light dust out. At this point I wiped it down again with a brake cleaner soaked rag, then blew out again and filled with Dot3 brake fluid, pumped the brakes a few times and just let it sit.

Over these last 2 weeks, I would occasionally walk by and just give the brake a couple pumps and walk away (couldn't work on it anyhow, life is too busy).

A few days later I have a red puddle (not the color of brake fluid) on my garage floor under the master cylinder & pump that got larger over this 2 weeks, that left quite a trail as you can see. I assume this is power steering fluid, and I also assume its because my booster pump is leaking.

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Picture of the of the master cylinder and booster.....including underside of them....

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On the passengers side I have a puddle of fluid on the garage floor that also got big over the last two weeks (to the front bumper in fact), and the inside of my rim and tire are wet from brake fluid. I also noticed fluid on the rear side of the inner fender well (like fluid shot up at it from pumping the brakes). I took this below connection apart just tonight and cleaned metal surfaces up to a shine, and also cleaned the copper washers, re-installed & tightened down.

After this I had my wife push on the brakes for me tonight, and that leak is coming from here at the connection to the caliper (did not squirt, it puddled up quick and started dripping). Look how this line is routed, it is touching the inside of my drop spindle, and is also lightly touching the upper ball joint nut. Is this correct????

Circle is where leak is coming from (I am pretty sure, suppose it could be elsewhere on that connection), and arrow is showing where the line is touching.

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Thank you in advance!!!
 
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Dave M

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OldBlueDually
That line tucked up hard against the ball joint does not look right to me. Perhaps the block needs to be repositioned to direct the line to the left from the caliper. (assuming it is the correct line) The line, because it is touching the stub axle, may not be able to allow the block to sit perfectly flat to seal, there should be a copper washer on both sides of the block.
As for the master cylinder, l would just replace it.
As for the Hydraboost, l would research and shop around for the best option.
When it comes to brakes and a budget, the two don't go together. Budget means shortcuts.
Remember, your going to load up that truck with your wife and kids.
 

Big Chip

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I had trouble finding a new hydroboost a couple years ago but did find one at O'Reilly eventually. Mine was leaking into the cab which seems to be a somewhat common issue.
 

OldBlueDually

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@Dave M I actually did try to re-route that brake line, no go. Yes, there are two copper washers (top & bottom) and everything is spotless clean, so it "should have" sealed up. I too think it is not perfectly flat, that is why I wanted to show you guys this and get an opinion. "IF" I had only taken a before picture......of this one part!

I had a feeling of "just replace it" would probably be the best option. I like to try to save stuff and make it work if I can, but I totally understand the safety side of it too.

@ali_c20 So this makes me wonder if someone prior put on the wrong brake line to the pass side caliper? I unbolted it to put on the drop spindle and put it back into place. The clip is on the upper control arm also, so it is not like I could reposition it wherever I wanted, which I did try and it did not work.

@Big Chip now that would tick a guy off because I have new carpeting and floor insulation in there!

I also saw, that someone has removed the 4 nuts that hold the hydroboost black plate to the firewall, and yet nothing moves or is wobbling, so I do not get it. I will look into replacing both the hydroboost and the master cylinder, and get new lines for the calipers.
 

Craig 85

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I think the hydro-boost flange at the fire wall has actually 6 bolts IIRC. In the first photo the top two are hidden. I just did mine about 6 months ago. I was leaking under the hood between the M/C and the booster. I was able to get a rebuilt one through Napa. I found out A-1 Cardone is the only re-builder for them by all auto parts stores.

My OEM set up had a removable rod set up. The new ones the crimp the rod into the back of the hydro-boost so it won't fall out. Napa had the wrong part in my box. The rod was about and inch short. Luckily, I didn't turn my parts in until the very end. The rod number on my K30 is 71271 as seen in the photo.
 

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OldBlueDually

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I think the hydro-boost flange at the fire wall has actually 6 bolts IIRC. In the first photo the top two are hidden. I just did mine about 6 months ago. I was leaking under the hood between the M/C and the booster. I was able to get a rebuilt one through Napa. I found out A-1 Cardone is the only re-builder for them by all auto parts stores.

My OEM set up had a removable rod set up. The new ones the crimp the rod into the back of the hydro-boost so it won't fall out. Napa had the wrong part in my box. The rod was about and inch short. Luckily, I didn't turn my parts in until the very end. The rod number on my K30 is 71271 as seen in the photo.

Good info to know, thank you! Not sure where my h-boost will come from yet.
 

Turbo4whl

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Did you put a new copper washer under the hose block? Sometimes it is necessary to file the rusted brake caliper flat to get a good seal.

About the hydro-boost, the master cylinder rear seal is designed to keep brake fluid from leaking out. If the front seal of the hydro-boost is leaking, yes most will drain out the slot. Left unchecked, the PS fluid will saturate the rear master cylinder seal. That seal designed for brake fluid, will soften and draw PS fluid into the master cylinder. I know this for a fact.

For anyone else to know, if your hydro-boost is leaking from the front seal and you just keep adding PS fluid, this is not a good temporary fix. Your brake master cylinder will fail. Yes, I have the T-shirt.
 

OldBlueDually

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Did you put a new copper washer under the hose block? Sometimes it is necessary to file the rusted brake caliper flat to get a good seal.

About the hydro-boost, the master cylinder rear seal is designed to keep brake fluid from leaking out. If the front seal of the hydro-boost is leaking, yes most will drain out the slot. Left unchecked, the PS fluid will saturate the rear master cylinder seal. That seal designed for brake fluid, will soften and draw PS fluid into the master cylinder. I know this for a fact.

For anyone else to know, if your hydro-boost is leaking from the front seal and you just keep adding PS fluid, this is not a good temporary fix. Your brake master cylinder will fail. Yes, I have the T-shirt.

I did not use new copper washers on the hose block. I did clean it all up really nice with a small wire brush wheel on my cordless drill (stuffed a tiny rag into caliper to keep crap out), and the copper washers cleaned up nice, as did the hose block. I torqued it down pretty dang good too....and it still leaks there.

As for the hydro boost, and the master cylinder the leak does look to be coming from where they meet. I am just going to replace them both after I do some shopping around.
 

Dave M

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I have reused the copper washers before, but I annealed them over a flame to soften them up and bite in.
 

ali_c20

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So this makes me wonder if someone prior put on the wrong brake line to the pass side caliper? I unbolted it to put on the drop spindle and put it back into place. The clip is on the upper control arm also, so it is not like I could reposition it wherever I wanted, which I did try and it did not work.
Many people just drop on what they can find in their garage or can get for cheap and make it somehow work. That's something I would not recommend doing on brake systems. Get the right hose for your brake setup and you have 1 thing less to worry about. I would change both front brake hoses, they are cheap. Your rpo sticker should contain the info which brakes (jb7 or jb8) you have.
 

AuroraGirl

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NOT RELATED to this question but the OP had a love for flatheads and I just saw his name again and This engine was tipped up before but it fell over now, but I took a photo... is that a ford flathead. I cant exactly visualize the thing upside down for ****
 

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