Hydrostratic whine

[rtallichet]

Has anyone heard of an fix for the loud whining sound in operation on hydrostatic machines. I have a 3901HST. Just doesn't sound right to me. Thanks

 

[North Idaho Wolfman]

The whine is probably normal, most wine pretty good, it the inherent downfall of hydrostatic transmissions.

It might get better after it's initial break in and you clean/change filters, and Use SUDT2 fluid.

 

[Forvols]

Might want to check the fluid level in the sightglass also. I have a L2501 Im going to the dealer to get some fluid, as I don't see any in the sight glass. So I think its low.

 

[skeets]

Remember in most cases you are sitting over the pump and the ROPS acts like a big old tuning fork

 

[North Idaho Wolfman]

Might want to check the fluid level in the sightglass also. I have a L2501 Im going to the dealer to get some fluid, as I don't see any in the sight glass. So I think its low.

Low hydraulic fluid will not necessarily make it wine, unless it's way to low.
Make 100% sure you not overfilling it as that will do damage.
Put a board or two on the ground and drive the rear tire up on it and then recheck the level.

 

[beaterboss]

My 3901 makes almost zero transmission whine when using Low Range during operation. (loader work, back blading, landscape rake). When I put it in Medium Range, noise gets a little louder, and in High Range it's quite loud. Maybe a range selection change to a lower range would reduce your noise level. The whine is inherent in Hydrostatic transmissions, but will likely reduce after the first transmission oil/ filter change. Some are just noisier than others. Use the recommended Kubota oil and dont skimp by buying cheaper stuff. Using cheaper stuff with cost you 1000x more than you saved in the long run.

 

[Ortimber]

My 3901 makes almost zero transmission whine when using Low Range during operation. (loader work, back blading, landscape rake). When I put it in Medium Range, noise gets a little louder, and in High Range it's quite loud. Maybe a range selection change to a lower range would reduce your noise level. The whine is inherent in Hydrostatic transmissions, but will likely reduce after the first transmission oil/ filter change. Some are just noisier than others. Use the recommended Kubota oil and dont skimp by buying cheaper stuff. Using cheaper stuff with cost you 1000x more than you saved in the long run.

Exactly how mine acts as well. Low is pleasant, medium tolerable, high range pretty loud.

 

[CaveCreekRay]

When I test drove my 126 hour L-3800 HST, I was surprised by the noise of the HST in HIGH at max travel speed. Sounded like it was gonna 'splode. I thought something might be amiss but, it was still under warranty so I took a chance. (My green buddy who went with me to haul it home thought the same thing.)

Still loud. Its an HST built to handle 40hp so its moving a lot of liquid. I wear wifi headphones and hardly notice anymore. If it stops making noise, get worried. My buddy's green machine is 25hp so naturally, its quieter.

I am coming up on the 400 hour HST service and will swap to SUDT2 despite some who say that it came with synthetic from the factory. Whatever, works great and lasts a long time.