Oil & Fuel Kubota B21 Foaming Transmission Fluid.

[TomSeller]

I wouldn't worry about the plug in the bottom of the HST, but if you find lots of sludge/water in the bottom you may wish to either air ratchet the bottom of the pan off or pull the entire pan, of course that depends how pedantic you are, and whether you intend to do another drain and fill in "X" hours down the track.
Don't forget the bit about running the engine at medium speed for a few minutes after changing the oil, before any use of the tractor. (just found my operators manual Code No. 32721-6311-7, what code no. is yours?)

Will the two axle drains drain the entire tank or does it take all three? My manual is at my other house. My used B21 did not come with a manual, mine is something I bought off of eBay.

 

[Carl_NH]

Tom,

You need to remove all three plugs - I got 2 plastic storage containers at Walmart for $4 that were 10" high - also I found it easier to remove the left rear wheel to access that side of the tractor. Not required but it made the access to filters and the strainer assembly.

I think the poster was referring to the plug in the actual HST pump NOT the plug on the bottom of the tank - you do need to remove that one - I did that one first then the two at the rear second.

Warm up the oil first for a while and get the particles moving, then drain the oil, remove the filters, then the strainer. I found it easier to get 3 2.5 gallon SUDT than a 5 gallon and 2.5 as its easier to pour from a 2.5 gal and was just a few $ more.

I used SUDT and only when I am working it hard I get a whiff of hyd fluid, never any foaming like you have. Good Luck and I hope the oil replacement works!

Carl

 

[Carl_NH]

On the FEL and BH cylinder draining before you drain out the fluid raise the loader up and the extend the BH out too, then when you are draining the fluid let the BH and FEL down which will force some of the oil in the cylinders out too. Obviously don't run the tractor but let gravity push the oil from them.

if you do this too, it will at least get more of the oil out - you may need an additional gallon of fluid instead of the 7.5

 

[100 td]

3 plugs as shown in the picture, one on each axle housing L & R.
I wouldn't warm it up and circulate the sludge and water through the oil first. I would drain it after it has settled for the day, as all the water will be at the bottom and hopefully will be flushed out better as most comes out first, then the flowing oil drags the rest. But of course that is a personal preference.

 

[100 td]

How did you go with this, much water?

 

[djbmw]

Sorry for reviving a VERY old thread but it's one of the first Google results so I figure I should add some flavor to the post.

I just finished changing my engine oil/filter, hydraulic oil plus filters (x2), fuel filter.. as well as the headlights but that's not important. The whole process too around 3 hrs. A good chunk of that time was spent waiting for oil to drain, or oil to fill up the reservoir. Of note: I have the benefit of a lift/hoist which made removing the hydro filters quite simple. It also allowed me to remove most of the fluid from all of the cylinders as well since I could prop up the bucket/boom/etc. with a transmission jack, tie back the corresponding hydraulic control stick, and slowly lower the tractor which would extend and/or compress the hydraulic piston and push the fluid into the reservoir (and out the drain plug into my pan).

I used three 15 liter (4 gallon) oil pans to capture all of the oil, leaving only a tiny drip on the concrete floor when I swapped out pans.

Overall, for me, it was a very simple process that resembled an oil change on most any truck and/or full size SUV. If you're not concerned with getting all of the oil out of the lines and hydraulic pistons then this should still take the same or less time even without a lift. I do, however, recommend that you raise the tractor up as high as possible with the bucket and backhoe legs, then place 4 jack stands under the tractor, so that you have enough room underneath to work.

Filters Used:

• PH3593A for the Engine Oil
• PH3682 for the HST (behind the left tire)
• BT8488 for the HST Reservoir (mounted under the middle of the tractor, immediately in front of the hydraulic oil reservoir)

Oils Used:

• 4 Litres of Shell Rotella T6 Synthetic 5W-40 for the Engine Oil
• ~30 Litres of Shell Spirax S3 TLV (Used to be called Shell Donax TD) for the Hydraulic Oil

Tomorrow I'll change out the axle oil but I dont see that being a lengthy process (other than waiting for the 90 weight oil to drain/fill)

 

[5030]

I stick with genuine Kubota filters. Fram is and has been substandard always. Kubota filters are only a few pennies more and sometimes the same or less. Far as Donax, never used that either but if it meets or exceeds the Kubota spec, it's good. I use Chevron All Weather THC Synthetic myself and it's pre colored in orange of all things. Easy to see the level. Like the Chevron as it's cold weather flowability is excellent.

Been my experience that foaming is caused by one of two things...

Incompatible fluids not intermixing or water in the fluid.

 

[rScotty]

Now that a couple of years have passed and I've had the chance to work on this problem a couple of times.
I've seen two main reasons trans/hydraulic oil foams, and either one can push a froth out the overflow.

To figure which it is, take a sample of the foamy fluid, put it into a clear jar, and see what happens in an hour or so. You can use a syringe and piece of tubing down the fill hole will pull a sample.

If the fluid was cloudy to start but clears up or turns into mostly clear oil with some foam on top then the foam is micro air bubbles. Usually from air being sucked into the system between the sump, filters, and the pump. Often it's an old hardened hose cracking at the end where it is held with a hose clamp. Or a loose fitting.
The fix is to stop the air from getting in.
Suspect the hoses and fittings. It won't leak oil out while running - except through the overflow - but might when sitting.

On the other hand, if the fluid after sitting looks like weak chocolate milk or is stringy and stays that way then that means water has gotten into the transmission fluid and made an detergent emulsion. This is real common with tractors that sit outside in the rain when water seeps past the shifters. I also had a friend see this after using rental attachments that we suspect had watery oil. A filter won't take the water out once it is well-mixed.
The fix for this is to drain, flush, clean filters, and refill.

Hope this helps,
rScotty

 

[djbmw]

"I stick with genuine Kubota filters. Fram is and has been substandard always."

After working on thousands of cars, and also cutting open numerous filters (partially for fun, partially to confirm a few Youtube channels that compare filters) I'm of the belief that as long as you're regularly changing the oil & filter, the filter brand doesn't make much of a difference. I encourage you to view some of those oil filter tear-down comparison videos on Youtube. The only difference of any significance across the filters is the bypass valve construction. Having said that, the Fram filters are generally glued to a carboard composite vs a steel cap which will only be a problem if you dont do regular oil changes. For me, these filters were available locally, on clearance, and with some stores closed and/or tricky to get to with COVID, they do just fine

 

[5030]

I prefer what I prefer, your experience many be different. I have a filter cap removal tool as well and internally Fram's don't compare but you already know that and I'm not getting into a filter discussion anyway. Don't have the inclination to.