Kubota B26 making a strange noise

[Gary Fowler]

My B26 began making a strange screeching noise for a few minutes when it is first cranked after sitting overnight. I typically sounds like a squealing bearing but the sound is only when depressing the HST pedal. As long as I don't exceed 1200 RPM and about half of the HST pedal, it is silent. If I increase the RPM AND the HST pedal, it starts squealing and the more pedal I give it the louder is the sound. This all disappears after about 5 minutes of warm up.

Any ideas what could be causing this. Everything operates normally except for the HST squeal. The tractor has 390 hours. HST filter and fluid was changed at 200 hours. Fluid was a universal fluid that was listed as equal to Kubota hydraulic fluid. The squalling just started about 10 hours ago.

 

[LarJea]

Sounds like a fan belt.

 

[BigBoyToys]

X2...sounds like a "classic" loose fan belt.

 

[dfkrug]

How cold was it overnight, Gary?

My theory is your oil is cold and needs to get a bit warmer before your HST wants to run
properly. Mine likes a minute or 2 warmup even when sitting at 50-60F. Longer if only
40F or so overnight.

 

[Gary Fowler]

Sounds like a fan belt.

Yes it sounds like a belt but it stops when the engine warms up. Belts are all tight. The noise stops after warmup of about 5 minutes. It started doing this last summer when the temps were in the high 70s in the morning. I don't think air temp was the issue. I suppose it might be a partially stopped up filter on the HST but I don't know how it (the oil) could be contaminated.

Hopefully someone with a similar problem that has been solved will chime in here soon.

 

[Gary Fowler]

X2...sounds like a "classic" loose fan belt.

Actually is sound more like a dry bearing squealing.

 

[LarJea]

It's still possible for it to be the fan belt. My Onan generator is powered by a Kubota 4 cylinder diesel engine and I had the same problem. I wound up replacing the original belt and the problem disappeared. You can check by spraying some belt dressing and see if squeal temporarily goes away, if not maybe going with Kubota super $ UDT hydro fluid instead.

 

[Gary Fowler]

Fan belt was tightened a bit more but still got the noise. Noise is only when I press the HST pedal. I can rev the engine up and down , press the HST pedal with it in N and no noise. The sound seems to be coming from the front of the tractor. I think tomorrow I will use the stabs and FEL to raise the wheels off the ground and see if I can find the vicinity of the squealing noise when I depress the HST pedal.

 

[Gary Fowler]

I did the jack up and was able to pin point the noise. It is coming from the front drive shaft. It has a plastic sleeve covering up a portion of the shaft where a direction change occurs. I suspect there is some kind of U-joint or CV inside. Now that I know what it is, I guess I will just continue to run it till it breaks. I may look at putting some lube inside if I can get the plastic sleeve to move easily so I can access it.