I second Gary T
Some Brake Parts Cleaner(Aerosol) will help clean up the mess. After installing the new Master Cylinder you need to carefully fill and bleed the brake system of air. You may also consider just draining the whole system and starting over.
If you need more help, come back
Capt
Careful with brake parts cleaner. They are solvent sprays and can remove paint and other coatings easily.
Brake fluid is water soluble. Use dish soap and water or Simple Green (or other brand of cleaner/ degreaser) and a brush to clean up the brake fluid mess.
Spray carb cleaner will dissolve paint, and brake parts cleaner will dissolve some plastics, but I’ve never seen a brake parts cleaner that dissolves paint.
Master cylinder swaps are relatively cheap and easy. You only need a few basic wrenches to get the thing unmounted,then you bolt the new one in and fill up the reservoir with clean brake fluid. You then have to get under the car (easy with the high ground clearance on a suburban) and loosen up a specific fitting at each brake. You have a partner start pumping on the brake pedal until the fluid runs clear and then tighten the fighting while the fluid is jetting out. (time it right so that air isn’t sucked in).
It’s only maybe 2-3 hours, tops. I did this on a sedan, and it cost about $60 for the master cylinder and maybe 10 bucks for the brake fluid. Autozone loaned me the tools. I’d imagine a big vehicle like the suburban might cost more like $150 for the master, but it’s still cheaper than the mechanic. (a well known brake shop in town wanted $300 for this repair)
I’d be thankful if it only were the master cylinder. As you can see in the video, it’s very easy to access. Replacing the booster requires me to dismantle my dash just to get to the linkage between the brake pedal and the booster.
My concern is the way the brake fluid shoots up like Old Faithful from way **below **the master cylinder. It’s kind of hard to see what exactly is gong on there because of the big wire bundle going across the bottom of the booster. How would the fluid get way down there then shoot upwards?
Well it is a pretty sure thing that the master cylinder is kaput, so I would start there. The replacement is likely to fix the problem, if not then deal with the booster. Make sure you clean the mating surfaces well and get the rust off the booster and possibly spray paint it. The master cylinder is probably a “core” part, meaning it will be rebuilt, so take it to the auto parts store with you.
Let us know
Capt
This kind does. First hand experience - it was one of the things I specifically used it for. Working on stationary industrial equipment, sometimes I had to uncover an old part number, or information nameplate, and Brakleen would always be my go-to to strip the layers of old paint.
It’s not paint thinner, but it’ll do.
I didn’t watch the whole video first time around, I stopped when I saw signs of fluid leakage from the back of the master cylinder. Sorry about that. Having now watched it, it appears that fluid is spraying out of the booster, which means a faulty booster.
It wouldn’t hurt to clean everything up and look carefully for any leakage from brake lines that are in the area. This can be checked with the engine off. Have someone press hard on the pedal. If the brake lines are dry, then any leakage will be easy to spot.
Normally the booster has no fluid inside. The fluid has come from the master cylinder, either because it’s worn and leaking or because the booster has a flaw that’s sucking it out of the master cylinder. Either way, assuming no leakage from the lines, both the booster and the master cylinder should be replaced. If there is leakage from the lines, that needs to be fixed but I’d still bet that the booster and master are toast.
Interesting. My experience is with using Brakleen to quickly clean accidental brake fluid spillage off of automotive finishes, and I’ve never seen it cause damage. I imagine it’s a matter of different type of finish, exposure time, or both.
Intimidating to peer inside one of those. You can buy rebuild kits but I don’t think I could work on one without crying. Automatics are filled with dark magic.
Looking at the video I think it may just be the passenger side brake line. The two lines come out of the Master cylinder and go to the anti lock system and if I am not mistaken the line for the front passenger side goes under the booster and along the firewall. An easy pump on the brake with the engine off will make it a lot easier to spot the leak. With the engine running the fan is blowing the mist all over the place.
In the video, at about 1:49, you can see most of the brake fluid comes up the side of the booster, but you can also see some come down on the steering column. No brake lines between the two. I checked last night to make sure.
It looks like the passenger side brake line goes quite a ways down into the engine compartment, maybe down by the transmission, before cutting over along the firewall.
Also, it looks like there is only one brake line heading to the rear brakes. Is that right?
Also, what do the letters “NA” on my master cylinder mean?
Try looking without the truck running, you will probably only get a pump or two before the pedal gets really hard, but get right in there and find where the leak is originating. A small pinhole in a steel line can shoot fluid a couple of feet with a hard push on the pedal, that’s why you don’t want to push too hard and fast, but don’t go so slow that it just trickles out.
Out of curiosity, how do you fix a broken steel brake line? That thing was bent somehow to neatly snake it’s way all around your car…do you have to purchase a new one that comes in a reel and somehow bend it to go all the way to the destination without scraping on the ground? How on earth do you bend a material like that?
Replacement brake lines are sold in various lengths ranging from about 12" to 60". They have fittings on each end to connect to terminal points (master cylinder, caliper, wheel cylinder, etc.) and can be coupled together to get the right length. Though made of steel, brake line is rather small (<¼" OD) and can easily be bent by hand. It can also easily be kinked, so tubing benders* are used to make smooth curves. Replicating lines with multiple bends at different angles is a tedious process, but with care the results can be good.
*Ignore the wiseacre remark written on the one – this was the best picture I found showing the types normally used, and when used properly they prevent kinking rather than cause it.
Well, you guys were right. Pinhole leak in the front passenger brake line - steel tubing. Even with the engine off and an easy press on the brakes, the fountain of brake fluid reaches the booster.
It’s way down in there, though. The brake line leave the ABS controller, heads back a bit to clear the driver side wheel well, then down to the frame where it heads back toward the front and under the radiator.
Fortunately there is a coupling before it goes under the radiator, so all I need to do is replace the line from the ABS controller to the coupling. It has a bunch of loops and such in the line. Do I have to replicate all of that? Once the line has been replaced, do I bleed all the brakes or just the passenger side?
The loops are to give some springiness to avoid cracking due to vibration. Probably not necessary to replicate them, but I would. Making loops is easy, just find something sturdy and round of about the right diameter and wind the line around it.
You’ll need to bleed whatever the line goes to. You can probably get most of the air out by bleeding at the coupling between the old and new lines, though it will be a messy process. I’d still follow the line to its terminus (caliper? wheel cylinder?) and get all the air out.
As a lifelong owner of a few suburbans and yukons I am very familiar with the vehicle setup. The 96 has the 5.7L Vortec which uses a “spider injection” system that uses “poppet valves” which render most fuel injector cleaners useless due to way the system is fed.
I was told by a GMAC certified mechanic that the Techron product would work wear others would not but I am a little dubious.
That said, you need to pull the codes, you likely will get either a P0300 or a P0301-P0308. The former means the computer reads a misfire but that it is random (i.e. not specific to a cylinder) which is actually better than the latter which specifies an actual cylinder.
If your code reads the former, your first culprit is the head gaskets which are notorious for being cheap “save a penny” plastic from the factory and can fail as early as 100k miles. If you replace them BE SURE to that your mechanic uses the UPGRADED FEL PRO MS98000 gaskets which far superior and about $15 more!
If your code is the latter, you could still have a head gasket problem but that also introduces possible leaky injectors or burned valves which can be much more problematic and add to the cost.
One thing to check if its the latter codes (P0301-P0308) is to pull the plugs and look for signs of fouling from coolant (plug will be much lighter, almost a tan color) which means coolant leaking from the head gasket into that cylinder, fouled the plug and caused your miss.
There are other suspects in a miss such as the EGR valve, CPS, timing/rotor and such but they the head gasket, injectors are generally the problem 90% of the time.
Best of luck.
