LTX1042 hydrostatic trans noise
 

So I have a 2009 LTX1042 riding mower with the Hydro Gear hydrostatic transaxle and it seems very noisy while in operation. I don't notice any loss of power and seems to work OK under all conditions. It just makes a medium pitched whine going forward or reverse. You can really notice it when engine is under full throttle.

I changed the hydraulic fluid recently because I figured maybe the fluid was contaminated or bad. The level looked OK, but the old stuff was quite dirty and dark and kinda looked like there were particles in it but I couldn't tell what they were. I sucked out around 1.5 quarts and put the same amount of new 20w50 hydrostatic transmission fluid in. I also made sure to purge the system at least twice. Did a test run and it didn't seem to make any difference because the noise was still there.

Is this thing just a noisy unit and I have to get used to it or do I have something else going on I should be concerned about?

I had a 2009 LTX1045 with the Hydro Gear. Mine had the same experience. I did the same thing you did. I syphoned out most of the fluid and replaced with 20W-50. No change. Mine had no loss of power at all (hills, etc. no issue).

I then had a 2018 XT1 (55 hours when I got it) with a Tuff Torq K46. Mostly quiet (a little whine). I replaced that fluid twice. No difference in sound or power.

I recently picked up 2021 XT2 with a Tuff Torq K46 (130 hours when I got it). A lot of whine. I replaced the fluid. No change in sound or power. It does just fine on hills, etc.

If you google that condition it will tell you as long is here is no loss of power up hills or after it gets warm, the whine is fine.

I realize the info below if for the K46 but I am betting it is the same for your Hydro Gear.

FYI

A low-level whining or growling noise in a Tuff Torq K46 hydrostatic transmission under load or when changing speed is generally considered normal operation for a hydraulic pump. [1] (https://www.tufftorq.com/tuff-torq-k46-oil-maintenance/), [2] (https://www.houzz.com/discussions/16...-noise)However, excessive, loud, or suddenly changing whines can point to fluid breakdown, air in the system, or internal wear. [1] (https://www.youtube.com/watch?v=otvSwZEW87Q), [2] (https://www.youtube.com/watch?v=b62hXa5QYD0&t=135), [3] (https://bobistheoilguy.com/forums/th...99/page-2)When the Whine is NormalLight hydraulic hum: Hydrostatic transmissions use fluid under high pressure, which inherently creates a functional whine—especially when going up hills, reversing, or accelerating. [1] (https://bobistheoilguy.com/forums/th...-noise.163281/), [2] (https://www.tufftorq.com/tuff-torq-k46-oil-maintenance/), [3] (https://www.houzz.com/discussions/16...-noise)Drowned out by blades: If you can easily talk over the noise or it gets masked completely when your mower deck blades are engaged at full throttle, it is usually just normal operating sound. [1] (https://bobistheoilguy.com/forums/th...e.163281/)When the Whine is AbnormalLoud, painful pitch: If the transmission sounds like it is straining loudly or you notice a sudden spike in pitch and volume, something is wrong. [1] (https://www.youtube.com/watch?v=b62hXa5QYD0&t=135), [2] (https://www.tufftorq.com/tuff-torq-k...ntenance/)Loss of power when hot: If the whining gets drastically louder as the mower heats up and is accompanied by a sluggish response or failure to climb hills, internal components like the pump plate or fluid are failing. [1] (https://www.garagejournal.com/forum/...static.366290/), [2] (https://www.facebook.com/groups/1173...29262490531/)A missing cooling fan: Check the top of the transaxle under the mower; if the plastic cooling fan is broken or fell off, the unit overheats rapidly and whines loudly. [1] (https://www.tractorbynet.com/forums/...ff.410887/)How to Fix or Reduce the WhineChange the oil: Many manufacturers call the K46 a "sealed lifetime" unit, but Tuff Torq recommends fluid maintenance under heavy use. Changing out dark, degraded factory fluid for a high-quality synthetic 5W-50 or 20W-50 oil often quiets the whine and restores power. Users discussing repairs on TractorByNet note that a simple drain and refill can bring an aging, loud transaxle back to life. [1] (https://bobistheoilguy.com/forums/th...estion.351240/), [2] (https://www.youtube.com/watch?v=otvSwZEW87Q), [3] (https://www.tractorbynet.com/forums/...7/page-4)Purge air from the system: If you recently worked on the unit or changed the fluid, lift the rear wheels, disengage the bypass valve, and cycle the drive pedal forward and reverse several times to bleed trapped air.If you'd like, let me know:How loud the noise is (can you hear it over the engine?)If the mower loses speed or power when going up hillsThe approximate hours on your transmission

Thanks for that. It may very well be a symptom of normal operation and it makes sense as long as nothing else is going on. I'll just have to get used to it since otherwise it runs fine.