Oil & Fuel Kubota B21 Foaming Transmission Fluid.

[Baby Grand]

Thanks for the learnin', rScotty!

 

[Weaselfoot]

During warmup, I think the pump shaft which extends to the PTO clutch is rotating within the transmission. Is it possible that the PTO valve is partially open so that the PTO clutch is making contact without being engaged enough to drive the PTO? Could that contact be overheating the oil and causing the foaming? One quick way to check would be to start the tractor from the non-foam state and then warm it up as before, except this time, activate the PTO.

In essence, I am backing up 100 td's suggestion above, check the PTO etc. Thanks to rScotty for that lesson in transmission theory!

 

[TomSeller]

There was no abnormal pump noise at all. Everything sounded normal. I do hear a normal pitch (to an HST whine) change when the tractor warms up like I would expect.

The tractor does not creep at all with the foot off of the fwd/rev pedals. I only set brake because it was a slope, mostly in case the tractor shut off for some reason.

On the oil testing, can they tell you what type of oil? ie gear, flushing, UDT, etc?

The DPO had a Fram engine filter on the tractor so he may be the type that might have bought the Supertech 303 hydraulic oil (not rated for HST from what I can tell) I saw at Walmart after seeing the post above from 100 td about the better SuperTech hydraulic oil. Sorry to those that might use Fram.

He did have Kubota filters on the hydraulic fluid, but that might have been since Walmart doesn't stock those sizes in Fram.

 

[rScotty]

There was no abnormal pump noise at all. Everything sounded normal. I do hear a normal pitch (to an HST whine) change when the tractor warms up like I would expect. The DPO had a Fram engine filter on the tractor so he may be the type that might have bought the Supertech 303 hydraulic oil (not rated for HST from what I can tell) I saw at Walmart after seeing the post above from 100 td about the better SuperTech hydraulic oil. Sorry to those that might use Fram.
He did have Kubota filters on the hydraulic fluid, but that might have been since Walmart doesn't stock those sizes in Fram.

The tractor does not creep at all with the foot off of the fwd/rev pedals. I only set brake because it was a slope, mostly in case the tractor shut off for some reason.

On the oil testing, can they tell you what type of oil? ie gear, flushing, UDT, etc?

That's good about the not creeping; to my mind it means neither the brakes nor HST is the problem.

On the lab, I don't know. If you do check with your lab please do post what you find....I don't know if mine can or not. Maybe I'll give the local one a call.

Can't resist the fun of a bull session and speculating - so my bet would be that some labs can and others not and it doesn't really matter because none of them I've heard of actually do that. The labs I've dealt with expect you to tell them about the basic oil you are putting in along with as much more info as you can.
What I look for - and hope not to find - from the oil lab's report is any unusual change in the proportion of certain mostly metal ions in the oil. Numbers that are out of line with the amount you would expect from that many operating hours on that oil. An example would be babbit or bushing bearing material in the oil. Bushing materials have a a specific analytic fingerprint. Any lab can and will spot it. Just to increase your tension, there will always have some. So the question becomes, "Is it significant?"
Is there more wear than last time or less?
Then there are things like beryllium, lithium, or moly friction reducers that are part of the additive packages in new oils and that get plated out on the inside of the engine so that their numbers decrease. And you'll see a pH change if any water got in there - but pH is linked to the gross amount of metal and carbonate ions so it isn't all that easy to sort out what it means.....things like that. Labs I've dealt with will usually help with the interpretation on things like pH. I always get that interpretation wrong myself. And it's up to you to decide if your operating hours are working the machine hard in tough rock, road time, or just idling. The hourmeter doesn't know nor care.
I love lab work and think it is worth the cost. But honestly I don't think I've ever once found out something I didn't already know or suspect. Sure is fun though...

On oils and filters I tend to use OEM filters and the factory recommended oils in my own machines. But that is more for mental convenience than any real knowledge on my part. After half a century of wrench bending plus an engineering stint - my own belief is that there is only a slight different in how any modern oils affect wear in an engine/tranny in moderate service. But foaming is NOT normal.

My recommendation is to leave your filters alone and just swap the oil out for something standard and dinosaur that you know won't hurt the HST. Something like NH MultiG 134 or JD 303. Use standard viscosity rather than low viscosity.


Luck,
rScotty

 

[TomSeller]

I have not needed to use this tractor and have not got around to changing the fluid yet. I needed to move it today and had to idle it for about 5 min but kept an eye on it. This is what the foam looks like coming out of the overflow tube. I will get new fluid in it ASAP.

 

[100 td]

I don't like the looks of that at all!
Don't forget the drain plugs on the brake/axle housings as well.
Pull the red fill and let us have a look inside.
And if possible some video inside when running from the start up.
Will your hoe stabilizers lift the tractor to full height at idle?

 

[100 td]

Don't forget to retract all cylinders on the FEL and HOE before draining the fluid, so you are getting the greatest possible amount of existing oil out of the system when you drain.

 

[sandyc]

Water in HST fluid?

 

[TomSeller]

Water in HST fluid?

No, the fluid is foamy not emulsified, it settles out as clear amber fluid. I think the last owner put some oddball fluid in there. I need to get it out, I'm just not on that property full-time yet to have time to do it.

 

[TomSeller]

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