J.D. 4040 Humming Sound.

My 4040 has developed a humming (roaring) sound. I believe it to be hydraulic related as it lessens a lot or completely stops when I drop the 3 point arms full down. I have changed the hydraulic oil, filter and screen.
Any thoughts would be appreciated.

First off...I am NOT a mechanic. But does the fluid heat up? Thinking a by-pass is messed up & forcing thru relief valve.

Are you in a northern climate where it's gotten colder lately?
My JD does that in the cold until it warms up. My ZTR does that all seasons when I first start it but it too goes away.
If you're at 1000 RPM's when you lift an implement, is it a lot louder then when at 1700 RPM's?

Thanks for the reply. I bet you're on the right track. I don't think the fluid is getting hot, although it does seem to get louder after use. The fluid looks good and doesn't smell burnt.I'm in the south so weather is still above 80 degrees. Does sound quieter at slower rpm's. How do you check bypass, relief valves? It is a cab tractor.

jd4040 said:

How do you check bypass, relief valves? It is a cab tractor.

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Like I said, I'm not a mechanic... I don't have a clue. Sorry, wish I could help ya.
HOPEFULLY, somebody will see this thread shortly that'll be able to help ya.