spool loader leak down

[n175h]

Hi guys,

It's been months since I've posted, but I'm back. My 1975 Case 580b has an annoying leakdown in the front bucket and digger bucket on the boom tower. I took it to John Deere (no case dealer around) to see if they could fix it, and they diagnosed leaking spool valve assemblies. I've got about 3 hours of shop labor in this now and still no fix. Kind of like going to a doctor isn't it?

Anyway the service manager says a spool valve assembly is very expensive and John Deere really can't get the parts. I can call Case and see what they say, but I have no way to get the machine to them.

What are my options here? Surely the valve assembly is rebuild able. It could removed and taken somewhere. I hope someone can chime in with a solution.

Thanks, David anderson

 

[Deon]

This is what I did with my JD control valve. I removed it, cleaned
it all up. Took each section apart one by one very slowly while
taking photos as I progressed. I took each chamber apart one at a time and then
put them back together only finger tight. I then went to a hydraulic
shop (there are some in every city, find the biggest one with a large
inventory) with my control valve all together but just loosely.
I then took each camber apart in front of the parts man where
we matched up each seal/o-ring and I reasembled it as he was
handing me the new parts. He was patient with me and in about 1 hr.
I was on my way back home where I put a wrench on everything.
Good luck.

 

[oldseabee]

First I would put down pressure on the bucket by tipping it down and then down pressure on the boom to lift the machine up, then let go of the levers and watch. If the bucket doesn't drift the other direction, it's probably a leaking port relief and not the spool. Port reliefs only affect one direction with the valve in neutral, leaking spool usually leaks both ways. In addition usually each circuit is seperated from the spool by a load check valve which is designed to hold the load in place while you shift the valve to raise the load and the pressure builds up by the pump to overcome the static pressure created by the weight of the load and then move it. If the load check is leaking, what you get is the load drops and then goes up when you pull the lever.

 

[melben]

Your money would have been better spent by getting it to a reputable Case dealer with a sharp service technician, I'll guarantee that the JD guy was only guessing based on his knowledge base. There are general facts concerning hydraulics and there are specifics that are prone to happen in certain models and this unit is no exception. Any experienced Case service tech knows that these machines had a history of blowing Orings on the check plugs underneath the secondary relief and that caused some unusual symptoms such as phantom movement of systems not actuatedd in addition to leakdown, for example if the boom was activated it would swing very slowly or any system with a blown oring could move with its spool closed. I would change all the check plug orings and the secondary relief valve Orings as well. It takes a specially ground 3/8 bolt to remove the check plugs, maybe someone who has the capability could post a pic. it is very simple to make once you see it and maybe someone could put up the dimensions. It would be wise to get some JIC caps and plugs and check the cylinders to eliminate leaky packing as a preliminary test. mEl

 

[stondad]

I agree with all that's been said so far, especially melben.
Unless I misunderstand, your problems are on both the front (or loader) bucket and dipper stick or boom of the backhoe. This means problems in two separate areas and possibly two control valves.
To answer your question, hydraulics workshops that I have managed or owned in Australia would accept your control valves as freight, strip and assess, replace or rebuild relief and check valves and fit a full set of seals. The assemblies would then be tested on a hydraulic test bench where each of the service port and main relief valves would be adjusted and each service port checked for leakdown. Once passed, the valve(s) would be sent back to you to refit on the machine with warranty. This is expensive and nowhere near as good as the "eureka" moment when you pull a service port relief valve cartridge out in the field and see an eroded Oring, and a new one fixes the problem.
If a "field" diagnosis isn't possible for you, you should be able to find lots of places in the States that can provide a similar service and won't rip you off.
There are cunning ways to check for cylinder by-pass. You may already have it covered, but why not reseal the cylinders on the faulty circuits before you pull out the spool-banks and send them away? You could find the problem there and at least you have kitted the cylinders or you can send the parts back if you find the piston seals are ok and you don't want to fit them.
For the record it is possible to have spools re-chromed. They are then ground perfectly round and the valve body is sized to suit. In most cases, the re-chromed unit is far superior to the original. Once again there must be lots of places in the States that do this but it is so expensive that you would only do it for a seriously hard to find part. I don't think this is your situation.
Your Case looks pretty nice. I think the JD dealer would like to have it in his yard for sale after spending not much on it and you drive away in a new JD or something out of his used yard. Good luck Mate.
I have to say that I am sending this post from Hervey Bay Australia (near Fraser Island) wearing only Speedos, so Deon you did a great job wearing mittens!
Merry Christmas and Happy 2012 to everyone!