Rebel Lord
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So brakes went out on the right side. Local Mx said the master cylinder is leaking internally. Is this something that can be fixed by swapping gaskets or does it need to be replaced? What’s the price tag for this repair?
PA-28 Master cylinder leaking
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Dan Thomas
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Needs new internal seals, which means that all the seals in both cylinders are probably old and failing.
Welcome to the world of "cheap" old airplanes.
Rebel Lord
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How much we talking here?
Ryan Klems
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Depends on which master cylinder you have (Piper used the Gar-kenyon 17000 and a few different Cleveland models pretty interchangeably, and they take different seals), but on the order of $40 for the seal kit, plus labor for R&R, rebuild and bleeding. And in for a penny, in for a pound... what condition are the other ones in, when was the last time the hoses were replaced, what about the state of the o-rings in calipers, etc ... most of the time I've been asked to do this job, the brake hoses hadn't been changed since the factory, there is external leakage on the hand brake and other master cylinders, calipers are often leaking, etc.
The Tech can likely replace the seals in under 2 hrs.
That leaves bleeding the brakes.
There are a few methods that work; sometimes!
Your person may not be aware of them..
It won’t hurt to gather up info to enable the Task.
Let the comments begin!
That leaves bleeding the brakes.
There are a few methods that work; sometimes!
Your person may not be aware of them..
It won’t hurt to gather up info to enable the Task.
Let the comments begin!
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paging @Timbeck2...
It's like those mystery surprise toy eggs. Could be a nickel of o-rings, or the whole thing is chewed up inside since nobody has ever looked at it since you were in diapers and it'll run you parts and labor and AOG time.
One path is to do things serially: take it apart, see what it needs, order parts, fix it, put it back together, bleed, parry, dodge, spin. With luck, you trade some time for money. Without luck, you fixed one part of a system, and then will be back later to fix the hoses, calipers...
Another path is to snag a good master cylinder off ebay aviation and swap, and do the hoses while you're at it. More money, less risk, less downtime overall. Maybe you can break even if the old unit can be overhauled.
It's like those mystery surprise toy eggs. Could be a nickel of o-rings, or the whole thing is chewed up inside since nobody has ever looked at it since you were in diapers and it'll run you parts and labor and AOG time.
One path is to do things serially: take it apart, see what it needs, order parts, fix it, put it back together, bleed, parry, dodge, spin. With luck, you trade some time for money. Without luck, you fixed one part of a system, and then will be back later to fix the hoses, calipers...
Another path is to snag a good master cylinder off ebay aviation and swap, and do the hoses while you're at it. More money, less risk, less downtime overall. Maybe you can break even if the old unit can be overhauled.
aterry1067
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I just went through this not long ago. My pilot side left brake was leaking so I ordered the rebuild kit, pulled the master cylinder (10 minutes), replaced seals (20 minutes), reinstalled it (20 minutes total) and bled the brakes (4 hours).
Then the following week, the hand brake started leaking. Order kit, remove MC, replace seals, install MC, bleed the brakes. Then the following week, the pilot side right brake began leaking. This is when I finally got tired of bleeding the *%!¥$@“?!( brakes, and ordered 3 rebuild kits to do the rest of the master cylinders.
My certificated labor is free for me, but if I was paying someone else to do it, I’d do all master cylinders at once. If any of the hoses need replaced, do this too. I’d only want to pay to bleed the brakes once.
This is most likely the kit you would need, but you or your A&P need to verify what MCs are in your plane.
www.aircraftspruce.com
Then the following week, the hand brake started leaking. Order kit, remove MC, replace seals, install MC, bleed the brakes. Then the following week, the pilot side right brake began leaking. This is when I finally got tired of bleeding the *%!¥$@“?!( brakes, and ordered 3 rebuild kits to do the rest of the master cylinders.
My certificated labor is free for me, but if I was paying someone else to do it, I’d do all master cylinders at once. If any of the hoses need replaced, do this too. I’d only want to pay to bleed the brakes once.
This is most likely the kit you would need, but you or your A&P need to verify what MCs are in your plane.
Piper PA28 / PA32 / Pa44-180 Series Gar-Kenyon Brake Master Cylinder Kit | Aircraft Spruce
Piper PA28 / PA32 / Pa44-180 Series Gar-Kenyon Brake Master Cylinder Kit Piper PA28, PA32, PA44-180 Series Gar-Kenyon Brake Master Cylinder Kit.
I can bleed brakes on a 150 in 5 mins. How do you do it, bottom up or top down?
Fill this with 5606, and get someone with a rag to watch the master cylinder vent. Fill from bottom up till person with rag says stop.
Fill this with 5606, and get someone with a rag to watch the master cylinder vent. Fill from bottom up till person with rag says stop.
Rgbeard
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Yesterday, I worked with my AP to replace the o-rings on my RHS caliper.
He used a garden sprayer with an attachment on the hose to bleed/fill from the bottom-up. We were done with that portion of the task in 20 mins, SRSLY.
He used a garden sprayer with an attachment on the hose to bleed/fill from the bottom-up. We were done with that portion of the task in 20 mins, SRSLY.
FYI
Cessna brakes bleed easily . 2 Master cylinders.
Cherokees with brakes for both seats can be more difficult.
5 Master cylinders and you may be pushing air down!
There are various methods but one size doesn‘t always fit all.
Note: The task can get more difficult if some clown used vise grips
on the bleeder valve!
Cessna brakes bleed easily . 2 Master cylinders.
Cherokees with brakes for both seats can be more difficult.
5 Master cylinders and you may be pushing air down!
There are various methods but one size doesn‘t always fit all.
Note: The task can get more difficult if some clown used vise grips
on the bleeder valve!
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Timbeck2
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Ryan who posted above works with me on my plane so he covered about everything. I had to replace all my hoses which came to about 11 of them if I recall. I also had to rebuild each master of which there are 5 including the hand brake. I have dual brakes. I don’t remember exactly how much it cost but the key thing is to crawl up under there with your camera and take pictures of all your master cylinders with the part numbers before you order the kits. I had three Cleveland and two gar Kenyon but the kits weren’t that expensive at all. The 11 hoses I think ran between 4-5 hundred. The labor was free since I did it under supervision of Ryan. There was a lot of cussing involved for sure.
Dan Thomas
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You got away easy. I bled the brakes on a Seneca after all five masters were rebuilt. Same as Cherokee system. It took two of us a very long time over a couple of days. You need a pressure bleeder forcing the 5606 into the calipers, and have someone in the cockpit working the masters back and forth to expel all the air. Air gets trapped in them, and it also gets trapped in any high spot in the brake lines, especially due to the dihedral of the wing, with the brake line angled upward for a long ways before it descends to the wheel. Pushing the oil either direction is a pain because of that.
Piper used a lot of hose, too, instead of more aluminum tubing, and the compressibility of the rubber hose liner makes the brakes spongy to begin with. Any air makes it much worse.
I can do it in 5 minutes too. Bottom up. See above for the difference with a Piper.
aterry1067
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I have found the easiest way for me is to disconnect the pedal side of each MC and secure them in an upside down config while slowly pumping the hand brake to start, then a sequence of hand and toe brake (gotta push it by hand as it is disconnected) until the bubbles stop. I also have to disconnect the pilot side right brake MC from the airframe side too, as it hits the center console support and will not allow the bottom hose to rise above the top hose.
From what I understand and have been told, the configuration of the MCs in the PA28 are such that a small pocket of air is left above the plunger and to get it out you either need to turn the MC upside down or move a crap ton of fluid through it quickly to suck out the air. Royal PITA.
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I Got this pressure bleeder from a auto body shop that was closing up in 1980 when my car was there unfinished. The owner said he thought the diaphragm was shot and was tossing it in the garbage. I opened it up and the diaphragm was fine, intact. There was a steel dish/ring that popped off the diaphragm that I snapped back on the diaphragm. Been using it ever since. I have overhauled it at least 3 times since then since most brake fluid is corrosive. The original diaphragm is still good today.
It has saved me lots of time and does a good job with plenty of pressure. Allows me to work alone. I would not hesitate to clean it out and use it with 5606 if I had a piper.
I am a media blaster/painter.
This is all I need for a Cessna.
I flushed my brake lines last year, easy deal.
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Ed Haywood
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Agree with others. 90% of time, replacing o rings will fix. If one cylinder is bad, other cylinder, calipers, and parking brake valve are not far behind. Since draining, filling, and bleeding the system is a large portion of the labor, makes sense to do all at once.
This is one area where owner working under A&P supervision makes a lot of sense. It's mostly simple work, hard to screw up, requires only basic tools, and you'll know on the ground after a quick taxi test whether you did it wrong. If you are mechanically inclined and have worked on car brakes before, this is easier. Find an A&P willing to check your work and do the log entry. Chances are they don't want to bleed brakes any more than you want to pay them to.
Order kits from planeparts.com, or download the Cleveland parts catalog and order the o rings and clips for your model number from Spruce.
OTOH, I was watching my A&P buddy bleed brakes on a PA28 yesterday and several ounces of water came out. WTF? Only thing we could think of was years of condensation in the unfilled reservoir of a badly neglected system in a tropical climate.
This is one area where owner working under A&P supervision makes a lot of sense. It's mostly simple work, hard to screw up, requires only basic tools, and you'll know on the ground after a quick taxi test whether you did it wrong. If you are mechanically inclined and have worked on car brakes before, this is easier. Find an A&P willing to check your work and do the log entry. Chances are they don't want to bleed brakes any more than you want to pay them to.
Order kits from planeparts.com, or download the Cleveland parts catalog and order the o rings and clips for your model number from Spruce.
OTOH, I was watching my A&P buddy bleed brakes on a PA28 yesterday and several ounces of water came out. WTF? Only thing we could think of was years of condensation in the unfilled reservoir of a badly neglected system in a tropical climate.
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Dan Thomas
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I made one from an old 25-pound propane tank. No diaphragm, so one has to watch that the fluid level doesn't get so low that you start pushing air into the system. Grrr. All that work...
Gary Ward
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Nice, I just got back from driving a propane tanker truck around town. I have several air tanks built out of propane tanks.
Oh yea checkout this homemade air compressor I built out of 2 100# LP tanks. This has been in service since 1984, still in my garage today and is always on as we use often.
Stand back! It is not OSHA approved!
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any suggestions on this? The maintenance manual talks about using the hand brake to pump it, but my Seneca IV doesn't have a handbrake, just a parking brake knob that activates a cam in the nose firewall.
Dan Thomas
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Best to let Piper mechanics do it. It's hard enough for those guys, never mind the owner. A pressure bleeder is almost mandatory.
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"Bleed brakes (4) hours"
I got a laugh out of this. The Cherokee started out with a single hand brake lever that doubled as a parking brake. Thing is, it worked perfectly fine but people were convinced they had to have toe brakes so Piper tacked them onto the existing system. But wait, people were convinced they had to have toe brakes on both sides so they hacked that into the system as well. The result is this Rube Goldberg maze where little Pac-Man-like air bubbles seek out and find little cubbyholes to hide in, sometimes unnoticed until they decide to come out and wreak havoc. Ask me how I know.
I got a laugh out of this. The Cherokee started out with a single hand brake lever that doubled as a parking brake. Thing is, it worked perfectly fine but people were convinced they had to have toe brakes so Piper tacked them onto the existing system. But wait, people were convinced they had to have toe brakes on both sides so they hacked that into the system as well. The result is this Rube Goldberg maze where little Pac-Man-like air bubbles seek out and find little cubbyholes to hide in, sometimes unnoticed until they decide to come out and wreak havoc. Ask me how I know.
The problem is that compared to most other brakes, the Pipers have their cylinders inverted. Long story short it makes it harder to get air out of it.
You can crack the lines, likely it won't get it firm. A pressure bleeder normally does not get the air out either. Even on conventional brakes it doesn't. A 172's pedals would be very firm even from a hand pump. Our DA-20s do not get firm just from a pressure bleeder, and a Piper will not get firm either.
If anyone is interested I'll share how we get Piper brakes firm...well, the firmest I've ever seen them at least.
well "duh"- of course we'd like to know!
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Seriously, do I have to subscribe and pay for this premium content?
Stewartb
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Brake masters are probably the worst maintained major component in GA airplanes. When you rebuild one you’ll recognize how bad the other one is. Rebuild both sides.
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The Piper service manual has the procedure. Turn the master cylinders upside down and it works great.
Ed Haywood
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And also among the cheapest and easiest to rebuild. Maybe $20 in o-rings and c clips. Once I rebuilt mine, I was embarrassed that I had ignored them for so long.
Stewartb
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Blow a master while taxiing between rows of planes and you'll never take your brakes for granted again. Spoken from experience!
Last time I did this I read online about some tricks and they worked. If you're doing one cylinder you'll likely need to bleed that side of both pedal sets, e.g. left on the pilot, left on the co-pilot since they share the same system. Figured that's known but just explicitly saying so.
After resealing the cylinders tighten the fluid lines but don't attach the cylinders to the pedals. With a constant supply of fluid in the reservoir on the firewall and the brake bleeder screw loosened, pump both cylinders by hand while holding them inverted. You can create a closed system to recycle the fluid which we did (a long tube going from the bleeder screw to the reservoir), or just continually pump fluid out and do what you will with it. We had one guy each under the seat just pumping the cylinders by hand. Actually worked, you can find people saying to do this but I will say it worked. They didn't turn out rock hard, but about as good as Pipers get.
I use the commercial ATS bleeder at work. It doesn't work well for Pipers because of the reservoir, and to be honest on a 172 or Piper it offers no benefit, but it helps on Diamonds. At my current workplace we tightened a hose around a fitting that screws into the reservoirs for DA-20s so you can bleed it from the bottom and catch it in a soda bottle. Perhaps you could do this for Pipers as well. Pumping the brakes while pressurizing from below works as well, we often have to do it for DA-20s while shaking the pedal vigorously, along with cycling the parking brake a few times.
I don't know why stuff is so finnicky. We only ever used a little hand pump as shown earlier on 172s. Gets the brakes rock hard. Often have to go through a soda bottle's worth of fluid to get a DA-20s brakes good and firm. And as everyone knows usually the copilot side just isn't as firm due to how the systems are made. I only work on DA-20s now so I haven't had the pleasure of bleeding a Piper in a few years.