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Cars > 55Stepside’s Garage > Blog > '79 Chevy truck brake problems


55Stepside’s Profile Photo


M –73
Charlotte, North Carolina
United States


'79 Chevy truck brake problems

By 55Stepside

I have been having problems with the brakes on my 79 Chevy truck. The right front brake almost locks up after I have driven it for a couple of miles. I have been told that it is water in the brake lines causing this. I was told to remove the master cylinder cap and open all bleed ports and let it gravity bleed as I add new fluid. I took the master cylinder cap off and removed the seal and it did have a lot of moisture under it. I bought a new seal and a gallon of brake fluid and have not had time to start the process. I would like to hear from the experts here on Motortopia to see if anyone has ever heard of this. Any input/suggestions would be greatly appreciated.


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Read comments on this blog post 1 – 10 of 12

gto_30’s Profile Photo
Apr 1, 2010 at 11:28 pm
I had the same problem in my camaro and i found that it was the brake line. It got slightly pinched when i put the motor in.
ricncars’s Profile Photo
Mar 21, 2010 at 1:40 am
the only reason it would even do that is you got air entering your brake system somewhere and tht would mean theres a crack or tear in your lines/ mabey the seal somewhere.
Bradnick’s Profile Photo
Feb 22, 2010 at 10:09 pm
Do not forget to check for a rotten hose line. It may be braking-down inside the hose and acting like a check valve causing the caliper to drag. The outside of the hose can look fine while the inside is coming apart. Good Luck. Brake Gremlin's
formulas7002’s Profile Photo
Feb 5, 2010 at 11:44 am
Hi Bill,

If you have water in the master cylinder, then it is can be, and probably is everywhere in the brake system. Most of the metal components in the system are iron - the brakes heat up as you drive, and that causes condensation, that is trapped in the sealed system and causes rust - works the same as the engine heat in your exhaust system rusting the pipe & muffler. That rust sediment works on the rubber seals in the various brake components like sandpaper, and will eventually tear them up.

In your case considering the age of the truck and that you are probably like most folks and just fix things as they fail, I would start out by getting a large can of dot 4 brake fluid (dot 4 has a higher boiling point so less condensation) and flush the system until the fluid is clear. Starting from the farthest point from the master cylinder PS wheel cylinder and working your way inward, ending with the DS front caliper. I know it seems funny to start by flushing the system - but you need to make sure the fluid is as free of sediment as possible to start off with.

Then I would take apart the offending caliper - and depending upon its condition I would repair or replace it, these days it is cheaper to replace it, unless you already have the proper hones to remove the rust from the caliper cylinder.

If it were my truck I would not stop there, I would put kits in the rear wheel cylinders or replace them, if you can afford to do that, then bleed the system, making sure that not only the air is out of the system - but that the fluid is completely clear of sediment.

My dad had a saying about brakes..."If your car won't start - that is an inconvenience. If your car won't stop - you've got a PROBLEM". Never skimp on your brake system, always use the best parts, and be thorough.

That's my two cents,

55Stepside’s Profile Photo
Feb 3, 2010 at 6:49 am
I would like to thank everyone who replied to this post. I am sooooooo lucky to have such great friends who are willing to step up and help me on this problem. A great group of folks here on Motortopia.

TerryO’s Profile Photo
Feb 2, 2010 at 8:27 am
Bill...before taking anything apart I would start by frushing the brake lines. Crank it up, starting with the rear right, rear left, front right, front left. Have someone pump while you bleed at each wheel while keeping an eye on and topping off the master cyl.
I read somewhere that brake fluid prolonged temperature cycle fluctuation from normal use causes it to have water like viscosity eventually. It's worth a try before breaking out the tools and tearing into the rebuild mode.
Flywheel401’s Profile Photo
Jan 30, 2010 at 11:19 pm
Hi Stepside, if you have water in ther than you most likely have rust ,Rebuild caliper if possible, or get a rebuilt/new unit. Check brake hose for internal damage ,that will also lock them up,by acting like a check valve ,bench bleed master cylinder than brakes. Bleed RR, LR, RF ,LF. adjust rear brakes. Good Luck !
LowRanchero’s Profile Photo
Jan 26, 2010 at 8:47 am
More than likely the caliper piston is sticking. Water may have caused it but I doubt just changing the fluid will fix it. I would change the fluid and clean the caliper piston(s) on both sides. It may work for the short haul if your lucky. You should be able to clean it without removing the brake line. However, you'll need to remove the caliper from the mounting bracket to get to the piston. I've done it before and it worked for a while. Good luck.
papabear5969’s Profile Photo
Jan 26, 2010 at 8:31 am
I had that problem on a 94 chevy that I own, I replaced the brake caliper and it still did it. I ended up changing the brake line and it stopped, the brake line had a weak spot and it was collapsing. Don't know if that helps but good luck.
twhotrod1968’s Profile Photo
Jan 26, 2010 at 5:59 am
just keep doing what your doing if that doesn't work try new pads

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