Model 95 back hoe troubles

[Catenary Kid]

Troops,

Many thanks for all the previous help - I may just be nearing the light at the end of the tunnel! Maybe. I have a JD 350 gas with a #95 backhoe. The crawler has a Drott 4 way bucket that works very well and has all kinds of power. The hoe, on the other hand... The hoe sat for many years before I bought the rig and when I first brought it home, it worked OK. I succeeded in blowing several hydraulic lines and just yesterday finished replacing all of the short lines from the control to the distribution block, all of the lines on the boom cylinder, crowd cylinder and bucket cylinder, then I drained and refilled the hydraulic reservoir with new fluid. After I ran the air out of all the cylinders (I think) the Drott works excellent - the hoe not so much. It is weak and neither the stabilizers nor the boom will lift the crawler off the ground. Besides that, I need to press the boom cylinder to it's upward limit before I can get any response from the crowd or bucket cylinders. Did I screw up the order of the lines? Is there a filter somewhere I've missed? Is this a valve problem or is there something else?

As always, your erudite comments and knowledgeable looks with head or chin scratching would be appreciated...

[original possum]

Check your boom lockout valve.

[Catenary Kid]

OK, Thanks!

So....what is a 'boom lockout valve', where do I find it and how do I check it? I've been through both the operators and service manual several times and never ran across such a thing....

[Jim B]

You may have crossed some lines. The blown hoses may have gotten contamination particles into relief valves. I am not sure all units had boom lock valve but it does show in the parts catalog. I expect it would be between the boom control valve and the boom cylinder. I would follow the hoses back from the cylinder and see if I find one before I get to the main valve bank. Maybe original possum will tell you where it is next time he checks in. (It would prevent the boom from moving during transport.)

You say you have gone through the operator's manual and service manual and don't find the boom lock valve. Just to confirm the manuals you have; the operator's manual is # OMU40033 and the Service Manual is # SM2062 for the back hoe, correct?

[Catenary Kid]

Again, many thanks. I'm banking on the crossed line - crap in the system approach. I'll keep you posted as I work through the process.

[Catenary Kid]

OK. First, I do have a boom lockout 'valve' and a swing lock, too. Both are mechanical. The swing lock is a 7/8" pin that drops into a hole into the yoke and through the casting on the swing cylinder. The Boom lockout is a square pin that drops through a casting forged into the lower boom. Nothing hydraulic about them. So my next question is: is there a way to clean out the relief valves or is it a better bet to just replace the whole valve stack as a unit? Given the complexity of the system, is it feasible to somehow flush the hydraulic system on the hoe to get all the crap out of it?

One more added curiosity: on the dash is a gauge that says "propane" on it. Has anyone ever seen one of these and does anyone have any idea what it is for? The 350 is a gasser not a diesel.

[Lavoy]

No clue what the propane tag would mean, no propane 350's factory built.
Lavoy

[Jim B]

Does the "propane" gauge show anything when the crawler is running? Does it display psi? What is the range?

You may have missed it before but what do you have for manuals (Names, publisher and publication numbers), some one may have the same manuals and might be able to reference something in them to help. The JD manuals for the # 95 backhoe are operator's manual # OMU40033 and the Service Manual # SM2062.

Did you replace the large supply and return hoses? Do they have quick disconnects? If they do have disconnects are they fully seated together. If it was working ok before you blew a hose and you are certain you have not crossed any hoses, I would lean towards either a piece of the failed hose, or some foreign matter, got into the relief valve.

Do you have a pressure gauge (5000 psi) you can use to check pressures?