strange sound

[boroxc]

Good morning and happy Labor Day to everyone!

I'm wondering if I can get some assistance from the knowledge base of this group. I have a 10 year old B2920 with 780 hours on it, and this spring my tractor started making a strange sound when I was taking it down the road to do a project at my daughters place. It was a downhill section of road and the sound seemed to be coming from the right front engine area while moving only. It would would stop when I took my foot off of the forward pedal and not return for a few minutes but would periodically return. The tractor worked fine and nothing felt different. Since then I've noticed the sound while mowing now and it appears to be occurring more often. I've checked all the fluids, I'm mowing in mid range, 2wd, and it seems to occur more on down hills and level ground than up hills with a load(????). The sound also goes away if I drop the RPM's.... To my untrained ear it almost sounds like gears grinding.

The sound starts at 1:50 in the video and that is where I turn to go down a hill....

Thanks in advance for any of your advice or assistance!

 

[5030]

Hydrostat whine. No biggie. Might need a fluid change. You do service it in a timely manner I assume.

 

[buckeyefarmer]

Think that is different than hydro whine.

 

[BubbaJr]

The hydrostatic whine is normal, but what I'm hearing sounds like a loose piece of tin rattling. Check your engine side panels on the right side, and any other sheet metal in that area.

Good luck,
Joe

 

[boroxc]

Hydrostat whine. No biggie. Might need a fluid change. You do service it in a timely manner I assume.

The sound appears different to me. You can hear the hydro whine going up the hill but it changes when I turn to come down. Yes its due for to have all of its fluids and filters changed at 800 hours. I may just do it now and see if that makes it better.

 

[boroxc]

Think that is different than hydro whine.

I agree! You can hear the hydro whine when I go up the hill but the sound I'm referring to occurs when I make the turn to come down the hill...

 

[3Ts]

It sounds like the load on the hydrostat pump changes from a high pressure to a low pressure - like an overrunning situation in a geared tractor. I suspect you only hear it when you're going down hill and that it does not start right away.

 

[boroxc]

It sounds like the load on the hydrostat pump changes from a high pressure to a low pressure - like an overrunning situation in a geared tractor. I suspect you only hear it when you're going down hill and that it does not start right away.

3Ts you are correct it does not happen right away.... Usually 10-20 into running it at higher RPM's.

 

[k0ua]

Sounds almost like a cavitation sound. Change fluid and filters and see what happens. I have had automatic transmission make some interesting noises with old fluid in them.

 

[ruffdog]

It does appear to be related to the hydro drive train vs loose panels or parts. Being that it takes a while for it to start making noise, I'm thinking it is because the fluid is hot and thinning when it does it. It sorta sounds like the rattle from a pressure relief valve....or hydro wave plate??? Sure, new fluid/filter may help it....who knows long term?:confused3:

 

[Chilliwack Murray]

The sound at 1:50 sounds very similar to what my 7510 does in high range when I travel at high speed, loaded or unloaded. It does this at fairly low speeds when cold and only near max speed when hot so I assumed it was a relief valve dumping.

I got my machine with 96 hours on it and it has always done it so I didn’t give it too much thought. I’m just about to do a 300 hour service now and wonder if it will change the sound with new fluid and filters. Since yours didn’t make this sound before it has caught my interest as well.

 

[Volfandt]

Were you in 4WD? I had similar sound on my BX23D, the plastic boot that covers the U joint at the front axle came loose and would occasionally rub the front driveshaft.

Double check your entire driveline to make sure theres nothing that can rub the drive shaft(s) at all angles.

Check the oil level in the front axle, could be low and the down angle makes it lower.