Problems with New Holland

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dalaplant

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Apr 7, 2006
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Hello, I recently acquired a New Holland 785 (1992 model) skid Steer. I don't know much about its past since I bought it at auction. What I do know is when I bought it had a bad hydraulic leak (turned out to be the filter seal was out of place). I replaced it and the leak was gone so I drove it slowly off the trailer. Once on the ground I added some hydraulic oil (a Kubota brand hydrostatic trans / hydraulic oil) to get the level back up to the dip stick low mark. I filled it through the dipstick hole since it was about an inch in diameter and I could get a funnel in there. Now it doesn't leak but also doesn’t seem to work well. I drove it off the trailer and that’s about as far as it went really. What I've found is if I start it and keep the engine at idle things kind of work, it moves (moves a noise like the pumo is working hard, like it would at the end of a cylinder range), the bucket goes up slowly and the pivots slowly, but if I turn up the RPM's it stops moving and stops operating the bucket. As you can tell I’m pretty new to the Skid Steer world so I’m not sure where to go next with this issue. Any advice about things I could check would be greatly appreciated. Thanks. Doug
 

Tazza

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It sounds like you have the wrong hydraulic fluid in there, the previous owner may have used the wrong oil with the leak. It could also be a filter blockage.
Can you easily access the hydraulic/hydrostatic pump? if so, run the machine for a few minutes then see if they are hot, if they are you are getting cavetation which is basically foamy oil. When it gets pressurized the air bubbles implode causing damage (slowly), lots of heat and jittery hydraulic action.
Youur best bet would be a filter change, and an oil change. Call the local dealer and ask where the filters are located and get a set off them. There may be more than 1 filter, not just the one that you fixed the leak on so ask the service people.
As you mentioned that increasing the RPM stops all functions, i would bet its a filter on the suction side to the pump. As when you increase RPM it moves more oil, but if it can't get it, it will just stop working. Some filters are made of bronze, hidden in port blocks, or inline with a hose at either end.
Good luck!
 

skidsteer.ca

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Jan 20, 2006
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It sounds like you have the wrong hydraulic fluid in there, the previous owner may have used the wrong oil with the leak. It could also be a filter blockage.
Can you easily access the hydraulic/hydrostatic pump? if so, run the machine for a few minutes then see if they are hot, if they are you are getting cavetation which is basically foamy oil. When it gets pressurized the air bubbles implode causing damage (slowly), lots of heat and jittery hydraulic action.
Youur best bet would be a filter change, and an oil change. Call the local dealer and ask where the filters are located and get a set off them. There may be more than 1 filter, not just the one that you fixed the leak on so ask the service people.
As you mentioned that increasing the RPM stops all functions, i would bet its a filter on the suction side to the pump. As when you increase RPM it moves more oil, but if it can't get it, it will just stop working. Some filters are made of bronze, hidden in port blocks, or inline with a hose at either end.
Good luck!
Ask dealer if this has a charge pump, what the psi shoud be and where you can connect a press guage to check it. Bobcat charge press is @60 psi, charge pump supplies oil to the main pump and/or hyrdro drives. MMy guess (like Tazz) is its a oil supply problem. But I'm not a teck, just a end user. Not sure one NH. Hope this helps a little Ken
 

dalaplant

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Apr 7, 2006
Messages
2
Ask dealer if this has a charge pump, what the psi shoud be and where you can connect a press guage to check it. Bobcat charge press is @60 psi, charge pump supplies oil to the main pump and/or hyrdro drives. MMy guess (like Tazz) is its a oil supply problem. But I'm not a teck, just a end user. Not sure one NH. Hope this helps a little Ken
Hello again all, Thanks for the great advice. After hearing about the pick-up filter I got worth the dealer to get a few pages faxed from the manual (I've since ordered one for the machine to have) and found the filter once I opened it up low and behold plugged completely up. I cleaned it up good out it back in and away I went... What a relief the pump isn't shot!! The story isn't quite over yet, in never can be can it.... After running it for a little while I checked the hyd. fluid level and the fuild was white as milk, which I understand means water in the lines. This leads me to a question, will draining the tanks and filters be good or should I take steps to drain the system (lines, pump)? If so how do I do that? And lastly, the tires on it are pretty rough (and a couple have slow leaks) so I'm planning to put new on. There are some cheaper tires on ebay that should get me by. My question is this: The rims are dented up, pretty good in a couple places, but still drive straight. Will I be able to mount new tires on them or will they need to be replaced? Thanks Agian, Doug
 

Tazza

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Hello again all, Thanks for the great advice. After hearing about the pick-up filter I got worth the dealer to get a few pages faxed from the manual (I've since ordered one for the machine to have) and found the filter once I opened it up low and behold plugged completely up. I cleaned it up good out it back in and away I went... What a relief the pump isn't shot!! The story isn't quite over yet, in never can be can it.... After running it for a little while I checked the hyd. fluid level and the fuild was white as milk, which I understand means water in the lines. This leads me to a question, will draining the tanks and filters be good or should I take steps to drain the system (lines, pump)? If so how do I do that? And lastly, the tires on it are pretty rough (and a couple have slow leaks) so I'm planning to put new on. There are some cheaper tires on ebay that should get me by. My question is this: The rims are dented up, pretty good in a couple places, but still drive straight. Will I be able to mount new tires on them or will they need to be replaced? Thanks Agian, Doug
Your tyres will not be a problem, worst case the people that change them for you can put tubes in if the rims are so badly knocked about that they won't seal.
Glad you sorted out your filter problem.
As for milky oil, if it is indeed milky from water and not white from air still traped in your system, you will need to change the oil. A double change would be a good idea. Drain all the fluid you can, replace the filters and re-fill the system. Run it for say an hour, working the machine a bit, then dump the oil again, replace the filters and re-fill.
Make sure the oil isn't just foamy before you go to the trouble and expense of changing your oil and filters like this. It may just be air traped in the system from when you cleaned suction line filter.
Good luck!!!!
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
Your tyres will not be a problem, worst case the people that change them for you can put tubes in if the rims are so badly knocked about that they won't seal.
Glad you sorted out your filter problem.
As for milky oil, if it is indeed milky from water and not white from air still traped in your system, you will need to change the oil. A double change would be a good idea. Drain all the fluid you can, replace the filters and re-fill the system. Run it for say an hour, working the machine a bit, then dump the oil again, replace the filters and re-fill.
Make sure the oil isn't just foamy before you go to the trouble and expense of changing your oil and filters like this. It may just be air traped in the system from when you cleaned suction line filter.
Good luck!!!!
Glad to here the initial problem was minor. Was the oil milky when you changed the filter? As Tazz said be sure the oil is not just foamy, if it still looks milky a couple hours after you shut it off, then its water contamination. It can be vary difficult to get all the old oil out some systems. warm the machine up to get the oil to run freely. Then I'd start but lift the loader right to the top and curling the bucket fully up, then shutting it down, and let gravity lower the loader and dump the bucket (do it over a hole in the ground so the lift arms drop fully) That way the hyd cylinders should push all the oil in them back into the tank. Drain you tank, then unhook and blow out whatever hoses you can get to, change your filter. After all this there is still a good chance your oil will get milky minutes after startup. If thats the case, do it all again. If you oil is foamy then somehow air is getting into the suction line to the pump and/or hydros. This can also be caused by returning oil to the reservoir above the fluid level. Return lines should always be sumerged. Ken
 

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