I just bought a M6040 Kubota 62Hp. The thing is sweet however it makes a occasional growling sound under the hood. Kubota says it the oil cooler bypass valve. It rumbles when it hot & cold. It doesn't affect the RPM, any input out there, please
its a optional extra on fel. its another hyd circuit for the loader to operate 4 in 1 buckets etc. your manual probably wont mention it. i don't know what the noise is but i am interested so please post a reply. i have never heard this noise in a kubota let alone a 6040. the only inherent noise in them is the funny squeak/groan the hydraulic shuttle makes on start up.
I've got about 90 hours on my M7040. I have no idea what you're talking about. Never noticed any growling. Except my stomach when I was having too much fun bush-hoggin' to stop to eat! Doesn't sound right. No pun intended.