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Case 580C Backhoe Control Valve reseal....

MurrayB

Member
Joined
Jun 6, 2020
Messages
23
Location
Victoria
I have a 1979 Case 580c backhoe that is leaking oil at the top end of the backhoe control valves. (just weeping). Otherwise the hoe works fine - sometimes although the left swing cylinder is 'weak' and requires slight operation of one of the other controls to get power to it.

Choices are to drop the spools (in place on the machine) and put new top and bottom o-rings on, or pull the full unit and have a hydraulic shop do the reseal - including resealing the relief valves and setting the pressures.

Anyone know what the rough cost of a hydraulic shop doing this would be?

Also, what is the process for getting the top spool seals out of the unit? Do they simply pick out easily?

Also saw a post by "fishfighter: from 2014 who did roughly the same work, but he replaced the relief piston's o-rings with the 'white case o-ring'. Can this be done without taking the relief valve out and therefore not having to reset/test its pressure?

Any comments or advice would be greatly appreciated.

I don't want to do this twice....

Thanks in advance.

MBady
 

Coy Lancaster

Senior Member
Joined
Dec 19, 2014
Messages
2,032
Location
Arkansas
Occupation
service tech
The load check valve o-rings are gone most likely. They are under the relief valves both top and bottom. You will probably need to remove the valve bank so you can get to them easier and replace the spool seals at the same time.
 

MurrayB

Member
Joined
Jun 6, 2020
Messages
23
Location
Victoria
Yes I have the full manual and can probably perform the breakdown and seal\o-ring replacement. I just don't have the setup to reset the pressure rellief valves. I don't really know if they have to be tested and reset??? Any thoughts?
 

stinky64

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Feb 25, 2017
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942
Location
java center ny
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big truck wrench/fixer of things
I removed and rebuilt the entire valve bank on my C, split the sections and replaced all those o-rings as well due to leaks and crappy maintenance from previous owner, didn't have to reset anything. Maybe I got lucky, but every function works as should. Used all OEM o-rings, quite pricey but only wanted to do it once.
 

MurrayB

Member
Joined
Jun 6, 2020
Messages
23
Location
Victoria
Good to hear. Its an older machine (1979). I never run it at high revs or punish it. Given this, wouldn't the relief valves be slightly less important in dumping excess pressure. Meaning - could I get away without resetting them (as you did), as I tend to baby the old machine?
 

stinky64

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Feb 25, 2017
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942
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java center ny
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big truck wrench/fixer of things
Mine's a 76, you're 3 years ahead of the game. ;) Don't know if RPM's really affect it as much as pressure.
 

franklin2

Senior Member
Joined
Aug 6, 2016
Messages
314
Location
Virginia
Good to hear. Its an older machine (1979). I never run it at high revs or punish it. Given this, wouldn't the relief valves be slightly less important in dumping excess pressure. Meaning - could I get away without resetting them (as you did), as I tend to baby the old machine?
I was told you can go too slow on the revs also. If I hear the pump moaning I will kick the engine rpms up some, and it quits doing it.
 

franklin2

Senior Member
Joined
Aug 6, 2016
Messages
314
Location
Virginia
P.S. If you get into this can you take some pictures and share your experience? I have a leak up in there somewhere also. I also noticed one of my stabilizer arms is suddenly falling in a hour or so. I am wondering if it's trying to tell me that might be where the leak is, that cylinder has been rebuilt recently. I think I saw there may be another separate valve assembly for the stabilizers? Sorry for the thread hijack.
 

stinky64

Senior Member
Joined
Feb 25, 2017
Messages
942
Location
java center ny
Occupation
big truck wrench/fixer of things
580C does in fact have a separate valve for stabilizers, from previous posts think yours is 480C not sure about them.
 

Tinkerer

Senior Member
Joined
May 21, 2009
Messages
9,445
Location
The shore of the illinois river USA
It wasn't too long ago one of the members resealed his control valve.
He did an awesome job.
He posted where he bought his O rings.
He was considering making up kits from his leftovers and offer them for sale on HEF.
I don't remember his username. :mad:
 
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