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Benjy, Technician
Category: Heavy Equipment
Satisfied Customers: 376
Experience:  10+ Years Experience Factory Trained John Deere, CaseIH, Kubota, Agco, Mahindra, Valra, Fendt,
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hydraulic system makes a whining noise..somewhere..relief valve

Customer Question

I purchased a 2005 Kubota M105S with 700 hrs on it. The hydraulic system makes a whining noise that sounds to me like it has a restriction somewhere. It sounds like maybe a relief valve is lifting. Not sure! The noise gets louder anytime you activate the hydraulic system - - the front end loader or any of the three remotes. The pressure seems to be okay, but I am not used to having a tractor that has noisy hydraulics. I'm afraid it is going to get worse and become an expensive repair. Also the three remotes have detent and float, but none of them work properly. They won't go to the float position without hanging up and the detents don't always kick out at the end of their cycles.   I was told that the spring inside the remote valve was too long and may have to be shortened. Sure need some help.
Submitted: 8 years ago.
Category: Heavy Equipment
Expert:  Benjy replied 8 years ago.

Ok, the this model did tend to have some hydraulic noise. Some things to check. Condition and type of hydraulic fluid will have quite an affect on hydraulic system noise. I recomend kubota Super UDT for this application. The fluid is recomended to be changed at least once a year, I know that with this few of hours it is unlikely that it has been changed, but keep in mind that condensation and to a smaller part evaporation will cause physical changes in the fluid. The first course of action is to replace the hydraulic fluid and filters. I would suspect that one of the remote valves may be sticking slightly and causing the system noise. The good news is a hydraulic pump on these is relatively inexpensive to replace if it does fail.


The valves are supposed to lock into float possition, however sticking in the other positions is almost always caused by corrosion in the detent housings, sometimes they can be removed and lubed and be made to work satisfactory. However often times they need to be replaced, I would suggest coating them well with a corrosion inhibiter such as Fluid Film, before installing the new detents.


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Customer: replied 8 years ago.
Benjy, I failed to tell you that I did do a complete changeout of the hydraulic fluid. I tnink it was about 15 gallons. I used Chevron THF. I also changed the filters which were Kubota. The noise was the same after the changeout as before.
Customer: replied 8 years ago.
Benjy I forgot to tell you that even though the tractor is 4-5 years old, when I got it, it still had the original hydraulic filters on it. I am sure that when I changed the fluid, that was the first time for this tractor. I also inherited a hydraulic leak that is located under the seat. I'm thinking someone has been into it before and this created the leak.
Expert:  Benjy replied 8 years ago.
Ok, well, I would still check to make sure the remote valves are in neutral but other than that it will require pressure, and flow testing with specialized tools. This would be a dealer situation. However as I stated before these tractors do seem have a bit of normal hydraulic noise.
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Customer: replied 8 years ago.
Benjy, you have really told me nothing. I was hoping you could be specific in diagnosing the problem, but you have been extremely generic. I am a man of my word and I will pay you what I said that I would. The correct answer is that you can't make a decision without doing pressure and flow testing.
Expert:  Benjy replied 8 years ago.

Well, yes in fact without pressure and flow testing all you are doing is general speculation. It is beyond the scope of most do it yourselfers and, for that matter a lot of repair shops to perform this testing. In this particular case, extensive testing can often be much more expensive than replacing components. I hate that REAL diagnosis can be so complicated. Specifically, the pump will need to be flow rated at each section of the system. Directly at the pump, and then at after each component in the system to pinpoint where the problem may lie. The most frustrating thing is that there may not actually even be a problem. Is your hydraulic fluid abnormally hot? If you are not heating up the fluid the likelihood is that there is actually no problem at all. You can try feeling the hydraulic pressure line as it goes through each component and see if anywhere along its path it seems to get significantly warmer. If it does, there is likely a restriction in that component.


Hope this addition info helps.