Kubota M4 Utility Tractor Transmission Whine

[5030]

Mine is all manual (FWA) but still has the proportioning valve for the travelling pack and last time I checked both with a liquid filled pressure gauge, both were within the spec listed in the shop manual.

I believe it's 280 psi with the throttle at pto rpm. I can look it up for you of you want me to.

 

[JP_Austin]

Yeah I suspect your manual operate version is just causing the 2WD hydraulic circuit to engage which is pressuring up that massive piston on the 4WD clutch pack, disabling it.

So if that’s the case even a manual operated machine theoretically can have the same noise. The only caveat may be if there are additional hydraulic lines running over to your manual valve. I could see that extra plumbing making the two machines behave differently if it’s just a subtle problem.

I’ve even thought it could be due to a harmonic in the power steering. Believe the source for the hydraulic pressure on these controls is the pump off the side of the gear case. If in 4WD mode you really don’t have a use for that pressure other than go to the bypass. At least that’s my present thinking.

Next time I get it good and warm I plan to search around using a longer wood dowel to act like a stethoscope in pinpointing the noise. If anyone can help isolate the noise that certainly will help all of us!

 

[Bush Whacker]

Not much there, for trouble shooting your choices are add fluid or split the tractor so small wonder the dealers don’t want to touch it.
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Thanks for the info sir.

 

[Bush Whacker]

Here is a video of my tractor with the same exact noise as the original post. Really which kubota can wake up and fix the issue. Dealer here in Ottawa Ontario says kubota knows nothing about the issue.

Video link

 

[rScotty]

Interesting problem. Thanks for posting the shop manual pages. Like others, to my ear it seems like a hydraulic noise that happens when the fluid is hot and the 4wd solenoid is actuated. Like a relief valve not fully opening.
I see in the pages you posted that there are several pressure check ports in the 4wd solenoid system. A decent pressure gauge is only about 100 bucks. If I was troubleshooting I'd run enough hose to put the gauge in the cab, then watch the pressure on those ports.
It's a place to start.

If I was just throwing parts at the problem to spend money instead of doing a proper diagnosis, I'd replace the 4wd solenoid valve, its pressure relief valve, and the diverter valve. I suspect that the last two would be the inexpensive ones.

But first why not have a look at those pressures. Cost is near nothing.

 

[Bush Whacker]

Update: Just got off the phone with a Kubota dealer in the Ottawa region. They have confirmed that Kubota is well aware of the issue and it is related to a pressure relief valve. Even after replacing it with a new one, the issue came back after a few hours. Good news is that they are working on it. I was advise to continue to use the machine as, other then it being annoying, it will not impact functionality.

 

[JP_Austin]

Great to hear. I’m suspecting the power steering pressure relief as it’s up near the cooler and that is about where my noise is originating.

 

[eagle107]

Yeah, my dealer put that new adjunct value on my M4 last year and it did not fix the problem either.

 

[sixdogs]

Update: Just got off the phone with a Kubota dealer in the Ottawa region. They have confirmed that Kubota is well aware of the issue and it is related to a pressure relief valve. Even after replacing it with a new one, the issue came back after a few hours. Good news is that they are working on it. I was advise to continue to use the machine as, other then it being annoying, it will not impact functionality.

Kubota is wonderful in that they fix things that need to be fixed and make things right.

 

[sea2summit]

So was playing with it today. Anyone else able to go run their tractor parked with the break and engage/disengage the 4WD a few times and see what happens?

Mine doesn’t lurch forward but it absolutely moves. I find that pretty disturbing. I would understand if it moved when I engaged because it pressurized the system I guess but disengagement as well? Something ain’t right, I’m about to see what it takes to get some official paper on this.