1991 New Holland L785 Loud Whine When Turning

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ruko

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Sep 3, 2006
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I have this posted in the New Holland catagory too and sorry about that. This catagory looks like it is read much more often however. Recently purchased this unit and everything works just great. It has dual wheel widetracks (eight tires total). Power and lift/bucket movements are smooth. However, a VERY loud whine comes from the machine when turns are made in either direction. The whine is not present when going straight backward or forward. The whine happens at any speed or engine RPM. It does seem to be less at higher engine RPM but maybe I can't hear it as well because the Ford diesel is making so much noise. The hydraulic fluid looks clean and the level is good. The filters have only 50 hours on them. The hour meter looks like it has not been tampered with and it says 1530 hours. But who knows about hour meters! Any ideas as to what is causing this loud whine and should I be overly concerned about it? Thanks for any input. ruko
 

Tazza

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As for the “Bobcat” section being viewed more often, this is just because people own more bobcat machines than any other that means more posts/views is all. In future, please keep the posts in the correct sections. Everyone will see your post, but most will not know much about that particular machine, thats why you don't have a mass of responces.
Even though the filters are only 50 hrs old it may be worth changing them, even cut them open to see if there are any metal particles inside, if there are you know there is a problem. Does it happen when the machine is hot, cold or both? did it just start doing this? As you say going straight is quiet but turning is loud makes me think you have a blocked filter or using oil that is too thin. You can check with your dealer to see if there are any hidden suction line filters (if they will tell you) a blocked suction line filter will cause this exact problem.
Its not really advisable to keep running your machine in this state if it is indeed cavitation from the pump starving of oil as it will cause damage. Cavetation will cause alot of heat and the imploding bubbles can actually cause pitting in pumps/lines/motors or cylinders. Avoid using the machine alot untill you get it fixed. See if you can run it for say 2-5 mins and see how hot your hydrostatic pump is, it should be no more than warm, you should be able to hold your hand on it.
Its normal for them to make a small noise when moving, but nothing really loud. Usually at full throttle you can hardly hear it.
 

ruko

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Sep 3, 2006
Messages
8
As for the “Bobcat” section being viewed more often, this is just because people own more bobcat machines than any other that means more posts/views is all. In future, please keep the posts in the correct sections. Everyone will see your post, but most will not know much about that particular machine, thats why you don't have a mass of responces.
Even though the filters are only 50 hrs old it may be worth changing them, even cut them open to see if there are any metal particles inside, if there are you know there is a problem. Does it happen when the machine is hot, cold or both? did it just start doing this? As you say going straight is quiet but turning is loud makes me think you have a blocked filter or using oil that is too thin. You can check with your dealer to see if there are any hidden suction line filters (if they will tell you) a blocked suction line filter will cause this exact problem.
Its not really advisable to keep running your machine in this state if it is indeed cavitation from the pump starving of oil as it will cause damage. Cavetation will cause alot of heat and the imploding bubbles can actually cause pitting in pumps/lines/motors or cylinders. Avoid using the machine alot untill you get it fixed. See if you can run it for say 2-5 mins and see how hot your hydrostatic pump is, it should be no more than warm, you should be able to hold your hand on it.
Its normal for them to make a small noise when moving, but nothing really loud. Usually at full throttle you can hardly hear it.
Thank you for the reply. I will clean or replace every filter I can find concerning the hydraulics. The noise is present hot or cold, doesn't seem to make a difference. It has been making the noise from the day I got it 5 months ago. Being a very novice skid steer owner, I didn't immediately worry about it. I have a pretty good maintenance manual for the unit and many filters are mentioned in it. Thanks again. ruko
 

skidsteer.ca

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Jan 20, 2006
Messages
3,853
Thank you for the reply. I will clean or replace every filter I can find concerning the hydraulics. The noise is present hot or cold, doesn't seem to make a difference. It has been making the noise from the day I got it 5 months ago. Being a very novice skid steer owner, I didn't immediately worry about it. I have a pretty good maintenance manual for the unit and many filters are mentioned in it. Thanks again. ruko
Ruko
It is normal for a loader to make more pump noise when it works harder. I would think that turning a machine with 8 tires would take a considerable amount of power. Does it seem to operate fine? or does it make jerky turns, sorta like the the pumps are surging . Does it make this same loud noise when its pushing hard into a pile of dirt. I would say my 773 bobcat get 50% louder when it is making a tight turn on dry soils. But it is kinda a subjective thing. If it operates fine and the only complaint is the “noise” I'd be trying to find another simular loader and checking with the owner to see if it acts the same.
It is a good idea to check your filters anytime you feel you have a problem. But you may not have a problem at all
Ken
 

ruko

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Joined
Sep 3, 2006
Messages
8
Ruko
It is normal for a loader to make more pump noise when it works harder. I would think that turning a machine with 8 tires would take a considerable amount of power. Does it seem to operate fine? or does it make jerky turns, sorta like the the pumps are surging . Does it make this same loud noise when its pushing hard into a pile of dirt. I would say my 773 bobcat get 50% louder when it is making a tight turn on dry soils. But it is kinda a subjective thing. If it operates fine and the only complaint is the “noise” I'd be trying to find another simular loader and checking with the owner to see if it acts the same.
It is a good idea to check your filters anytime you feel you have a problem. But you may not have a problem at all
Ken
Ken Thanks for the reply. I have replaced all the filters in the unit and cleaned the suction screen too. There is a bar magnet in the suction screen filter and it had, what I would consider, quite a bit of iron filings on it. If I saw that much iron junk in a motor for example, I would be worried. I have been told however, that iron on this magnet is normal because of all the gears and chains, etc. the hydraulic oil is in contact with. Would you agree with this? I had to use an air impact wrench to get the cover off the suction screen so I don’t think it has ever been off. I had my neighbor, who has owned and wore out many skid steers, listen to the noise it makes and he says it sounds more like an intense vibration than a whine to him. The hydraulics operate very smoothly and there has never been any jerky movements in any of the systems. I am considering having a New Holland mechanic make a house call, which they will do for lots of money, and listen to it. Can you tell me how to make paragraphs in this forum? Thanks again, ruko
 

charger

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Joined
Dec 28, 2006
Messages
74
Ken Thanks for the reply. I have replaced all the filters in the unit and cleaned the suction screen too. There is a bar magnet in the suction screen filter and it had, what I would consider, quite a bit of iron filings on it. If I saw that much iron junk in a motor for example, I would be worried. I have been told however, that iron on this magnet is normal because of all the gears and chains, etc. the hydraulic oil is in contact with. Would you agree with this? I had to use an air impact wrench to get the cover off the suction screen so I don’t think it has ever been off. I had my neighbor, who has owned and wore out many skid steers, listen to the noise it makes and he says it sounds more like an intense vibration than a whine to him. The hydraulics operate very smoothly and there has never been any jerky movements in any of the systems. I am considering having a New Holland mechanic make a house call, which they will do for lots of money, and listen to it. Can you tell me how to make paragraphs in this forum? Thanks again, ruko
yes there will always some iron in the strainer filter coming from the chains and the gears,as for the noise its kind of hard to tell what is going on without hearing it for myself!,we`ve had units that have started to make noise while turning on one side but they are also lacking in power on that side,usually a pump problem(worn out)
 

charger

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Dec 28, 2006
Messages
74
yes there will always some iron in the strainer filter coming from the chains and the gears,as for the noise its kind of hard to tell what is going on without hearing it for myself!,we`ve had units that have started to make noise while turning on one side but they are also lacking in power on that side,usually a pump problem(worn out)
also check if your hydraulic oil is milky (water in oil) this is a problem with these machines and can cause severe damage to the pumps! water usually enters the top chain case covers!
 

skidsteer.ca

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Jan 20, 2006
Messages
3,853
also check if your hydraulic oil is milky (water in oil) this is a problem with these machines and can cause severe damage to the pumps! water usually enters the top chain case covers!
Clean the screens and check them again in 25 hours or so. If you make turns on wet ground or mud is the noise much quieter? I suspect it have to do with twisting all that track on the dry ground.
Ken
 

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