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case 580SK brake leak

mbavers

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homer alaska
1994 580 Super K. Master cylinder loses fluid intermittently. I've added about 1/2 gallon this year. I think the fluid level in the transaxle is high. No visible fluid leaks, so I guess leak is internal and I have to drop transaxle. Only the correct hydraulic fluid has been used-no brake fluid. My question is what is usually the problem? I'm thinking the rubber O-rings in the pistons, but my mechanic is doubtful (I haven't brought him the machine yet, just the service manual). If anyone here has had this problem please tell me what the solution was. Bad O-rings? Pitting in the piston or housing? Just want to get an idea if it's fixable or should I take it out behind the barn and shoot it?
 

Willie B

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It's been a while. Mine had a bad slave cylinder. They sit above the transmission with a rubber cover.

Willie
 

Willie B

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Mine is a K. I was only aware the difference extended to turbo. I'd be surprised if brakes are different. I'll look at my manual.

Willie
 

mbavers

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On mine the master cylinder is on the firewall and two lines go from the master cylinder to the top of the transaxle, one line on either side.
 

Willie B

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Mine is a casting that bolts to the side of the transaxle. At the top of each is the cylinder that actuates. I'd guess any leakage would go down into the transaxle, possibly diluting the transaxle fluid. I can't remember which K needed it, I think the one I no longer own. We put a seal kit in.

Willie
 

oceanobob

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oceano california
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Some K's are known as Series I and others as Series III. The transaxle being one of the differences. I believe one method to discern is the gear shift lever: does it come up out of the floor or is it on the 'console'. If it is Series I it comes up out of the floor - what we would call a shift lever top loader LOL. On this series I model, there are a pair of slave cylinders at top the transaxle: if seat removed then floor board tis not too bad a job to R&R but necessary to drain then remove the side covers to access the link/clevis.... Am more familiar with the Series I than the III in regard to the transaxle.
 

alrman

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You will find the problem to be the seals on the brake pistons.
The design unfortunately, causes small metal flakes to accumulate behind the brake piston & this causes some scoring in the main transmission housing.
In saying this, it can usually be repaired by removing the transaxle, then the axles, & resealing the pistons. The housing can often be reusued after a good polish with some fine emery cloth.
Occasionally, the housings require more than just a polish.....:rolleyes:

:professor **NOTE - When you remove the axle housings, there is ONE bolt shorter than all the rest, mark it's location & refit accordingly :professor
 

dixon700

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pa
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You will find the problem to be the seals on the brake pistons.
The design unfortunately, causes small metal flakes to accumulate behind the brake piston & this causes some scoring in the main transmission housing.
In saying this, it can usually be repaired by removing the transaxle, then the axles, & resealing the pistons. The housing can often be reusued after a good polish with some fine emery cloth.
Occasionally, the housings require more than just a polish.....:rolleyes:

:professor **NOTE - When you remove the axle housings, there is ONE bolt shorter than all the rest, mark it's location & refit accordingly :professor
I just used my 94 super k last week and the brakes worked perfect like they have for the last 5 years I've owned it. Today I fired it up and the pedals went to the floor, I refilled with a hytran plus equivalent, the left brake pumped back up firm, the right is still real soft and I dont see any external leaks. Do these seals just go out out of nowhere? Does the entire transaxle have to be dropped? I doubt I could pick up the transaxle and set it on a bench, especially since the only one I'd have enough room on is in my basement, could probably clean off an old desk in my barn, but back to I'm not gonna be able to lift it...
 

alrman

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@dixon700 Unfortunately, that can sometimes be the nature of the beast.
Your RH pedal will probably begin to feel a little better when you move the machine around a little - it seems to help.
Some of my customers have topped their master cylinders for quite some time before they eventually get sick of doing so & call me in to do the repairs.

Keep in mind, the longer you leave the repair & continue to use the machine - the more scoring is being done to the brake piston sealing area in the main housing......:rolleyes:

In answer to your questions
  • Yes, the transaxle needs to be dropped. I have seen them done by lowering the transaxle, leaving it under or even hanging from the other side of the machine (which is as good as ready for complete removal) & removing the axle using floor jacks etc ..... trouble is, the seals on the other side are probably in the same condition & should be replaced - but there's no way I would contemplate doing this repair in such a manner.
  • The bench will need to be made of steel - these transaxles weigh every bit of 1 ton!
  • You could use a good quality transmission jack to lower the transaxle out from under the machine, leave it on the jack & use timbers to support it - then use lifting equipment to remove the axle housings from the main housing. - you will obviously need a concrete floor....
  • A forklift, using fork extensions is the removal tool of choice.
 

dixon700

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@dixon700 Unfortunately, that can sometimes be the nature of the beast.
Your RH pedal will probably begin to feel a little better when you move the machine around a little - it seems to help.
Some of my customers have topped their master cylinders for quite some time before they eventually get sick of doing so & call me in to do the repairs.

Keep in mind, the longer you leave the repair & continue to use the machine - the more scoring is being done to the brake piston sealing area in the main housing......:rolleyes:

In answer to your questions
  • Yes, the transaxle needs to be dropped. I have seen them done by lowering the transaxle, leaving it under or even hanging from the other side of the machine (which is as good as ready for complete removal) & removing the axle using floor jacks etc ..... trouble is, the seals on the other side are probably in the same condition & should be replaced - but there's no way I would contemplate doing this repair in such a manner.
  • The bench will need to be made of steel - these transaxles weigh every bit of 1 ton!
  • You could use a good quality transmission jack to lower the transaxle out from under the machine, leave it on the jack & use timbers to support it - then use lifting equipment to remove the axle housings from the main housing. - you will obviously need a concrete floor....
  • A forklift, using fork extensions is the removal tool of choice.
I was afraid you were going to say they weigh all of 2 tons. I was thinking heavy, but wasn't thinking that heavy. Idk if my grandpa's little mahindra could lift it... My barn is dirt floor and my garage is too small, but I can use my trans jack out where it is now on my concrete driveway to pull it out. Are piston seals likely the only thing I'll need? My backhoe has 4000hrs is there anything else I should do while I have it out? Is there anyrhing special thats needa to be done to remove the transaxle? I guess I'll have to get my service manual cd out....
 

fpgm04

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Dixon700,

For what it may be worth, I have seen this issue after very cold weather, not in hot. Not saying it could not occur in hot conditions, I just have not seen it. Perhaps the seals are more pliable when warm.

In any case, there is tradition brake bleed screws on top of the transaxle. From experience, I am suspecting you may be able to restore your RH side by bleeding the brakes, at least temporally, if the weather does not get too cold. I have done this on a SK and it has lasted several years until another very very cold winter hit, but your mileage may vary. Certainly a full repair as Alrman describes is the recommended solution.

To bleed the brakes on the SK, you have to take the seat out, and the rear cover plate on the cab floor. The screws are on top of the transaxle on the LH and RH sides, just forward from the opening in the floor under the seat location. For me this means laying face down with some small wrenches and enlisting some young (read : smaller in size) helper to stand above me to press on the brake pedal as instructed, while I work the bleed screws. I am sure someone has figured out a more graceful way, but this has always worked for me, and the kids get to be truly involved with a real repair.

If you do decide to bleed the brakes, please note this is just removing the air from the system and the brakes are only going to be as good as the seals in the system. Use at your own risk.
 

dixon700

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pa
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Dixon700,

For what it may be worth, I have seen this issue after very cold weather, not in hot. Not saying it could not occur in hot conditions, I just have not seen it. Perhaps the seals are more pliable when warm.

In any case, there is tradition brake bleed screws on top of the transaxle. From experience, I am suspecting you may be able to restore your RH side by bleeding the brakes, at least temporally, if the weather does not get too cold. I have done this on a SK and it has lasted several years until another very very cold winter hit, but your mileage may vary. Certainly a full repair as Alrman describes is the recommended solution.

To bleed the brakes on the SK, you have to take the seat out, and the rear cover plate on the cab floor. The screws are on top of the transaxle on the LH and RH sides, just forward from the opening in the floor under the seat location. For me this means laying face down with some small wrenches and enlisting some young (read : smaller in size) helper to stand above me to press on the brake pedal as instructed, while I work the bleed screws. I am sure someone has figured out a more graceful way, but this has always worked for me, and the kids get to be truly involved with a real repair.

If you do decide to bleed the brakes, please note this is just removing the air from the system and the brakes are only going to be as good as the seals in the system. Use at your own risk.
Thanks for that, but I plan on owning this backhoe for most likely a long time. So I plan to just do the real repair.
 

alrman

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For me this means laying face down with some small wrenches and enlisting some young (read : smaller in size) helper to stand above me to press on the brake pedal as instructed, while I work the bleed screws. I am sure someone has figured out a more graceful way, but this has always worked for me, and the kids get to be truly involved with a real repair.

LOL! You can actually pump the pedal while laying on your gut - kinda like riding a scooter :p;)

@dixon700
When you drain the oil, pull the suction screen out & be sure there are no thrust washers present - if there are they will need to be replaced while it's apart.
You may need brake discs; the backing plates have locating tabs which could be broken; - you won't really know till you pull it down.

There are quite a few tricks to removing the transaxle, but I'm not quite ready to let the whole internet know about them.
Raising the machine high enough to allow the transaxle to go out from under the machine & using stands to ensure it stays there while your under the machine & for the duration of the repair is of high priority.

Just think about what you have to do, how your going to do it & KEEP SAFE!
 

fpgm04

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Alrman, Once again you leave me in awe and wonderment of your knowledge and physical skills.;) I have never been able to contort my legs to pump the pedals on a SK and reach the bleed screws at the same time. No doubt my gut size factors into the loosing equation for me.:(:rolleyes:

In any case, as you noted sometimes people just add oil until they decide to repair. I was only suggesting Dixon may want try to bleed the brakes in the short term, as it sounds like he is going to be doing the repair outside on his driveway, and it is still Winter time up here on this side of the equator.

Dixon700, as Alrman stated be careful and be safe
 
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dixon700

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Alrman, Once again you leave me in awe and wonderment in your knowledge and physical skills.;) I have never been able to contort my legs to pump the pedals on a SK and reach the bleed screws at the same time. No doubt my gut size factors into the loosing equation for me.:(:rolleyes:

In any case, as you noted sometimes people just add oil until they decide to repair. I was only suggesting Dixon may want try to bleed the brakes in the short term, as it sounds like he is going to be doing the repair outside on his driveway, and it is still Winter time up here on this side of the equator.

Dixon700, as Alrman stated be careful and be safe
It was snowing earlier when I was looking for any external leaks... I live in Pa, so I would just be removing it outside. I'm just wondering if I should wait til it warms up... As long as we dont get a foot or more of snow I wont need it anytime soon.
 
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