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Ohio City Ohio | Looking at buying a 792, but its got some hydraulic issues. when we looked at it/played with it some functions didn't hardly work, if one was very gently while moving stick very little it would work, but as soon as you would go to far the particular function would stop. some functions seamed to work all the time one way but not the other. Swing function seemed to work all the time. One track seamed to always work while other needed that slow gentle movement of peddle for it to try to move. Owner says once warm everything works but is slow and said one hydraulic pump growls. We did not hear any growling other than a bang when you move lever to lift boom up to far/fast. Its all mechanical valves and linkages with a lever going from valve bank linkage to top of each hydraulic pump, I assume some sort of "demand" signal lever for lack of better words. Don't know much about this hydraulic system but seems to be that one pump is not working like it should, or the mechanism that controls pump is not working like it should.
So does anybody have suggestions on the issue and or have any suggestions to trouble shoot further? Have not bought this machine but price is right and pretty clean machine. Would be ok to spend some money on it but don't want to buy a pump hoping that fixes it and than having more problems.
Edited by wffoker 10/26/2017 08:52
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West Tennessee | I like a good project as much or more than anyone. Personally I wouldn't do this one. My fear would be that there has been or is an ongoing hydraulic issue that has (or will soon) contaminate the system. I realize this might not be the case but I would be afraid to chance it with the dollar volume of repairs, and especially time, that could be involved. I would rather find an older machine that had less issues. A trackhoe is ALL about hydraulics. Good luck in whatever you decide. They are very useful. We have a Deere 120C and would have liked to have had bigger but just couldn't swing the money. |
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Big Sky Country | I got a log loader with 60 gpm.
It's basically 2 30 gpm pumps with one designated for each stick. Neat setup as when you initiate movement with second stick, it don't slow down what you already got going with the first one.
Sounds like this setup may be similar with one pump or 'side' having issues.
Pretty good odds pumps are the same age. |
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East Central wisconsin | I would definitely pass on that one. Excavators have a 10,000 hour design life. And can go beyond that with good care throughout its life. But the point of no return comes quickly on the old machines. Save your money for the next one. Sorry.
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Southern Illinois | I've got a deere 270 and it's a double pump machine I recently just lost the rear pump this summer and it was similar to yours I got lucky and didn't lose any shavings in the system but certain functions would work others would not. Deere wanted to install a reman for 12k I took it to a local pump shop and they checked specs I got out for 4500 which I thought was good. But we will see how long it lasts for a farm machine I'm hoping it was a wise decision. I bought my machine last summer and I'm more picky then others so I've spent some money on it I will agree 100% that older machines will get in your pocket I'm wishing I would of found something newer but hopefully I'll be in decent shape now. |
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SW Illinois | +1. The cost of repairs on these things can make your head spin. One that age with those problems would have to be dirt cheap to be worth taking a risk on. |
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Ohio City Ohio | I appreciate your thoughts on telling me to pass, but wouldn't it be wiser to figure out what's wrong with it first and than decide if it will be worth the money, The current owner does not know for sure what is wrong with it, but he has same opinion as most of you guys... as in "dump if for whatever i can get". if it just needs a small part or even if it needs a $4000 pump, if that is all that it needs this is still a good buy, if it needs a $4000 pump and than needs another $5K of other stuff than no this machine wont be worth it, But current owner is basing the selling price on a few grand more than scrap, its got a good running jd 466 in it, body is pretty straight and clean, all mechanical engine and controls, hydraulic thumb, 8K hours, lot of positives in my book. Id like to know where i can find a smiliar simple machine for the money.
Edited by wffoker 10/26/2017 13:37
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West Tennessee | I understand your question and I'll bite on it. I bought a big old skytrack with a good motor but a known bad hydraulic pump one time. Gave the guy what I figured was about scrap price. Turns out the hydraulic pump was kind of an "overseas" type of deal and super hard to find. Also once upon inspection there were for sure pieces of brass in the hydraulic system already. There was NO WAY of rebuilding that pump. My scrap deal was just that. Then I had to load the thing on a trailer and haul it. So you can see my experience with hydraulic issues hasn't been good and thus my advice. If you have the time and are willing to chance that maybe it's an easy fix or even willing to spend the money and time then go for it. Now days I'd really prefer to buy something that runs and I can use just fine today. That said I just took on another big old project...you guessed it...it was cheap. See Below. I should have taken pictures of the patch job we were doing up there. But I couldn't post them anyway because they were NOT NAT approved. Time will tell how this pans out. I guess it's do as I say not do as I do. :-) Good luck whatever you decide.
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East Central wisconsin | A older used excavator is not like a old used tractor. A old used tractor can be limped along almost forever. But not a excavator! A excavator has a limited usefull life. And its value is the condition of the hydraulics, not the engine or frame components. A excavators hydraulic components are so expensive, because its system pressure is so high. (5000 psi) for the whole machine. Most machines today peak around 3000 psi. With only hydro drives going higher. The best use for that machine right now ,is as a parts machine. To salvage any salable components, then scrap the rest. Sorry, just my opinion. But good luck.
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Davenport Washington | I like to work hard and not so smart so I would spend some money on filters and cut the old ones apart and see what's inside. If you wanted to spend the time you could drain the oil so you can get to the screen and bottom of the tank. If it's really bad just filter the oil and put it back in and walk away. |
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Kingdom of Callaway - Fulton, Mo 65251 | I bought a 892 last spring - if he decides to scrap it, I'd be interested in the used thumb.
I bought an older Cat excavator years ago and it did what you are saying that one is doing. We paid a cat mechanic to come out and check pressures on the pumps. It turned out the problem was it had a pattern changer for the controls and it was partially turned/stuck. I'd get a rough quote from Deere before you have the mechanic out - it could get pricey fast. Maybe the seller will split the cost with you so you both find out? Get a firm purchase price from the seller beforehand in case its just something simple! |
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Illinois | I would pass on that deal unless you are willing to spend a lot of repair money on it. The Deere / Hitachi excavators of that era only filtered the hyd. oil as it returned to the hyd. tank.
When a pump failure happens all the contamination and metal debris runs through the whole system including the finals drives before metal debris is filtered away. Good luck.
Edited by illinifarmer1 10/26/2017 22:50
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jd 792 excavator hydraulics question
