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Old 01-26-2010, 08:38 AM   #1
brady-yzf
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Location: Lafayette, CO, USA
Equipment: L35, BT900
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Default Hydraulic Whine-L35

I'm getting a hydraulic whine and it feels like the pump is laboring in my 2001 L35 whenever I am not moving my loader bucket either up and down or rotationally. The fluid and filter is brand new and all other hydraulics are disconnnected.

Here is the chronology:
I first heard the whine when operating my BT900 backhoe, I noticed at the same time that my dipperstick started extending very slowly. It still contracted at the normal rate with the normal force, but the extension was slow and weak. I dissassembled the valve assembly, inspected and cleaned it and put it back on. That was not the problem. I was advised to replace the seals in the dipperstick piston; those parts are on order but I'm not sure that that's the problem.

I removed the backhoe so I could still use the loader and I'm still getting the whine and the "feel" that the pump is struggling when the engine is running. The whine goes away when I'm moving the loader. Should I check the loader valves? ANy input would be very helpful, thanks!
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Old 01-28-2010, 03:41 AM   #2
ipz2222
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Location: chickamauga ga usa
Equipment: L235, bx2670
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Default Re: Hydraulic Whine-L35

Im not familiar with your tractor but,, a hydralic whine is caused by 3 things. Restriction on intake side, pump trying to mantain max pressure and pump vanes or rotor scarred and rubbing. Either 1 of these or all together.
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Old 01-29-2010, 04:50 PM   #3
pat331
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Location: Ft. Worth, TX
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Default Re: Hydraulic Whine-L35

Brady-yzf

I had a similar experience with my L35. Turned out I did not have one of the rear hoses from the backhoe completey inserted together. Properly inserting the hoses together cured my problem. Hope this is simple fix for you.
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Old 02-03-2010, 08:08 AM   #4
brady-yzf
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Default Re: Hydraulic Whine-L35

Well, I can tell you what it's NOT. I dissassembled both the backhoe and the loader valve assemblies as well as replaced the seals in some of the hydraulic pistons that weren't working properly. I dissassembled and inspected all the quick connects to make sure none were obstructed.

Perhaps I'm not adequately describing the symptom: It's not really a loud, high-pitched whine, but more of a slightly audible noise when the machine is in neutral hydraulic position. It's a noise that sounds like the pump is under load. I'm hypothesizing that the problem could be with a stuck relief valve. I think this because the noise goes away while an attachment (either loader or backhoe) is moving. Do relief valves commonly get stuck?

THe other thing is that the noise is not that bad, but I've never noticed it before. I don't want to fix something that isn't broken.

Thanks,
Brady
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Old 02-04-2010, 06:32 AM   #5
Service Dept Vic
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Default Re: Hydraulic Whine-L35

Disconnect the main pump "in" line, the one that goes right into the top of the hydraulic pump and see if you have a piece of foil or flashing right at that point restricting the pumps intake.

The tractors relief valve may have a piece of crap in in as well, causing the operating system to operate at a much lower pressure, clean and check.

Also take a look at the relief valve cartridge on the loader control.
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Old 02-07-2010, 11:49 AM   #6
brady-yzf
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Default Fixed! thanks Vic

I dont' exactly know where the little piece of crap was, but I cleaned the pump and the relief valve, and now she's fixed and ready for more abuse! Thanks for the help-
Brady
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Old 05-09-2011, 08:22 PM   #7
wakokaila
 
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Default Re: Hydraulic Whine-L35

Quote:
Originally Posted by Service Dept Vic View Post
Disconnect the main pump "in" line, the one that goes right into the top of the hydraulic pump and see if you have a piece of foil or flashing right at that point restricting the pumps intake.

The tractors relief valve may have a piece of crap in in as well, causing the operating system to operate at a much lower pressure, clean and check.

Also take a look at the relief valve cartridge on the loader control.
Hi,
I have several heavy equipment under my section and experience a similar problem with one of my graders. The hydraulic pump whines when the machine is on Neutral and the sound goes out when the machine is put on gears. Do you think it would be a similar solution as to what you are discussing here? Thanx..
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