Go Bottomb7800 hydraulic noise
 | beaston
Join Date: May 2010 Posts: 4 virginia 
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2010-05-25 171100
I have a 2006 B7800 with 145 hrs. I started having a "whining" noise from the pump in medium or high gear, rpms around 2000 at full pedal. It will go away if I back off pedal, but screams when back on. It will eventually go away after about 10 minutes at max temp. Fluids have always been changed and tried a new filter and fresh hydro fluid with same result. The pump noise seems to be getting worse. Any ideas?
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York 
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2010-05-26 171114
I'd hope that you did use the kubota filter and SUDT? ....
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| beaston
Join Date: May 2010 Posts: 4 virginia
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2010-05-30 171198
I used the proper kubota filter and case udt as sold by our local kubota dealer. They use the case udt in everything except the zd's. I had the noise before I changed the fluid though. I also cleaned the strainer and removed some small metal shavings, normal I'm told. The local dealer has been out twice now and has heard the noise. The tech tried to go in reverse as fast as poss. up hill to "burp" the system. Sounds like bs to me. The whine will go away after about ten minutes but returns everytime the machine is cool and has been sitting. ....
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| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2010-06-01 171258
Burping the system huh? Okay, the Case Ultra hytran is a good oil although I recommend it for many applications I can't say we have ever used it in a Kubota.
I believe it is just a bit thicker then the super UDT although many dealers just use UDT in the warmer climates.
Many hydraulic noises only come in and things misbehave when the oil is hot instead of cold like yours. It might be interesting to see what the super UDT would do?
We do stick with the manufacturers recommendations for oil when trouble shooting systems. We all know that the thicker the oil the higher the pressures, maybe with your system it might help with your start-up noise.
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 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2010-06-01 171267
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The whine will go away after about ten minutes but returns everytime the machine is cool and has been sitting.[/QUOTE]
Tell the mechanic to go back to school, and the dealer to put the proper fluid in your machine!
Change the fluid (you can leave the new filter) and this time refill it with Kubota SuperUDT.
I'm willing to bet the sound goes away within minutes and never comes back.
'Regular' UDT is too thick is the whine you hear is the relief valve (which under normal conditions) should rarely move, is now opening & closing at a horrendous rate to try to mechanically keep the excessive pressure down to a reasonable level.
The reason it goes away is the heat from the huge amounts of friction caused by the relief valve is causing the UDT fluid to heat up to the point it thins out to nearly SuperUDT weight, then the valve stops making noise.
As an example, the spec. I have shows Case Ultra Hy-tran has a viscosity of 40 at 40°C. (104°F.) but just 6.3 at 100°C. (212°F. ).
Best of luck.
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Add Photob7800 hydraulic noise
| beaston
Join Date: May 2010 Posts: 4 virginia
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2010-06-01 171271
thanks for the info. I will add that the noise began while I still had the original fluid from the factory in the tractor. I then changed the fluid and filter to hopefully remedy the noise thinking something was hung in the filter or strainer. I don't know what to do with it now. ....
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| Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2010-06-01 171281
Your dealer should have used a gauge to check the pressure when cold as well as warm to be sure that the pressure is right! If it is still under warrantee then get a hold of a manager at the dealership and procede with an appropriate fix, my thoughts are that if the dealer recommended the use of the Case oil then ask him to get it fixed!
Your relief valve might just be getting weak, nothing to the oil! ....
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Add Photob7800 hydraulic noise
 | kthompson
Join Date: Oct 2005 Posts: 5275 South Carolina
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2010-06-01 171282
Art, does Kubota ship their tractors filled or dry on fluids? ....
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