Please Diagnose This Bad Noise

[jc7622]

I have a 5740C with about 300 hours on it. 90% of its use is with a brush hog or with a 3 pt sprayer.

Today all of a sudden it started making this bad rattling sound that sounds like a bearing is going out or something, but it only happens in certain situations. It DOES NOT make the noise if it is out of gear, regardless of engine RPM. It also DOES NOT make the noise if it is in gear but the clutch pedal is pressed down, regardless of RPM. It only makes the noise if the tractor is moving forward and then only in the higher gears. For example:

LO 1st - No noise
LO 2nd - No Noise
LO 3rd - No noise
LO 4th - Barely can hear it
HI 1st - Can definately hear it
HI 2nd - Definately louder
HI 3rd - Very loud and concerning
HI 4th - Sounds like it is tearing itself apart

I can hear the noise in the cab coming up through the floor. If I open the left door the engine noise drowns it out. If I open the right door I can hear it coming from underneath the right side of the tractor. If it is in a gear that causes the noise the noise increases with RPM's. It makes the noise regardless of whether the PTO is engaged or not.

Any idea what this might be?

 

[LD1]

based on your description, i think we can rule out the engine, clutch, and pto.
It is also unlikely that it is a transmission because the noise is there in more than one gear. It sounds like it is only speed related, faster=more noise slower=less noise. I think the axles and hubs spin too slowly to cause that much noise so my logical conclusion would be something in the final drive. But with only 300hrs nothing should be bad already. If it is still under warrenty, i would definatally give your dealer a call.

 

[MikeD74T]

You might try jacking up one rear wheel at a time to see if you can cause the noise in a stationary environment. Might help determine if noise is from one side or from center. With one wheel stopped the other will spin at twice indicated speed so there will be less engine/ transmission noise to deal with. MikeD74T

 

[montanaman]

Have you checked the oil levels in the final drives? May sound like a simple question but they don't fill with the main transmission oil and it's worth a quick look.

Ken

 

[jc7622]

I got on the tractor today and the noise was gone. Then I noticed that the front wheels were not being driven (no 4WD).

Now does anyone have any ideas what it might be? Maybe something in the transfer case?

 

[Eagleview]

Is there an exposed driveshaft with universal joints going to the front diff ? If so you may have broken a UJ . As the noise increases proportionally with the tractors road speed it is drive line related .