Non HST hydraulic fluid

IdahoNative

Active member

Equipment
Kubota B7100D 4x4, non-HST, FEL 1630
Jan 12, 2022
118
46
28
Florida, central
My tractor sat for years before I purchased it. The hydraulic fluid was milky white and had water in it. I drained it overnight, replaced it the next day. I had to do this a few times to flush the old fluid out. That was expensive! BTW, mine doesn’t have ANY screens, just a hydraulic filter at pump intake. I have three questions:

To flush the system, can I simply put the lower tank line that goes to the hyd pump into a 5 gallon jug of new hydraulic fluid and place the return line into a separate 5 gallon container? I would cycle the FEL and 3 pt too.

What should hydraulic fluid look like after about 30 minutes of use? IMO, mine looks too dark. The glob in the middle is a paper I accidentally dropped.

Did all models come with hydraulic screens? Should I buy and install them?

thanks!
 

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GreensvilleJay

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BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
Apr 2, 2019
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to 'flush', I've always filled with oil, then run/use for an hour( good and hot), then drain for 24hrs.
the longer you let drain, the more oil will come out. Tractor needs to be on level ground of course...

oil color isn't 'bad', heck the machine's 37 years old so it'll never be 'clear or light tint'. My 55 year old tractor is darker after an hour of use.

don't know about screens, maybe check 'online parts' ??
 
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TheOldHokie

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My tractor sat for years before I purchased it. The hydraulic fluid was milky white and had water in it. I drained it overnight, replaced it the next day. I had to do this a few times to flush the old fluid out. That was expensive! BTW, mine doesn’t have ANY screens, just a hydraulic filter at pump intake. I have three questions:

To flush the system, can I simply put the lower tank line that goes to the hyd pump into a 5 gallon jug of new hydraulic fluid and place the return line into a separate 5 gallon container? I would cycle the FEL and 3 pt too.

What should hydraulic fluid look like after about 30 minutes of use? IMO, mine looks too dark. The glob in the middle is a paper I accidentally dropped.

Did all models come with hydraulic screens? Should I buy and install them?

thanks!
Dont over think this. Your tractor is a gear drive. Drain thoroughly and refill with some inexpensive UTTO like sold by TSC. Walmart, NAPA, etc. Start and cycle the 3pt a couple times. If no visual sign of water contamination you are done. If there is still some water in the system repeat as above.

AFAIK all of those tractors had a pickup screen in the sump and nothing else. If yours is missing replace it.

Dan
 
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Vigo

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B6100, B8200
Jan 9, 2022
595
340
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San Antonio Texas
The dark stuff is likely coming off all the 'walls' and non-meshing surfaces on the sides of gears, inside tubes, etc. In other words, it's not exactly critical that you get it all out, because it's not like its coming from the actual wear surfaces between the gears, in the pump, shaft bearings etc. However, this is the reason why some people say 'don't do a flush on really old fluid, you'll pick up all the stuff off the walls and put it back into circulation'. Well, they say that about cars, anyway. I don't really agree with it except to say that if you're GOING to put a new detergent fluid that is supposed to carry that stuff in suspension, you probably should keep flushing it until it stops coming back dirty, otherwise what they say is somewhat true. But usually that's said in regards to automatic transmissions which are far far pickier than manuals. With manuals practically the only concern is the compatibility of the fluid with the material on the synchronizers, but guess what you don't have any! You can even find examples in the car world where the manufacturer recommended ATF, motor oil. and gear oil for the same manual trans, depending on what year of the service manual you looked it up in! Oh, and different fluid capacities too. SAME TRANS!

My suggestion though is to use the cheapest fluid you can get your hands on to do these flushes, even if it isn't tractor fluid. ATF or motor oil would also be ok. The main thing is that you get the correct fluid in it the last time around, IF it's even picky, which i don't think a b7100 is.

So i guess that's a lot of words that amounts to, either call it good and stop, or keep flushing until it comes back clean (with the cheapest fluid you can get your hands on), it's up to you and neither approach is likely to hurt the machine in any noticeable way. In my opinion 'operator error' is a lot more likely to hurt an old gear trans than the difference between any number of oils, or whether the fluid is perfectly clear or not.
 
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PoTreeBoy

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L35 Ford 3930
Mar 24, 2020
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BTW, mine doesn’t have ANY screens, just a hydraulic filter at pump intake.

Did all models come with hydraulic screens? Should I buy and install them?
I don't think you need a screen if the filter is on the pump suction. My L35 is like that - filter, no screen.
 
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IdahoNative

Active member

Equipment
Kubota B7100D 4x4, non-HST, FEL 1630
Jan 12, 2022
118
46
28
Florida, central
Dont over think this. Your tractor is a gear drive. Drain thoroughly and refill with some inexpensive UTTO like sold by TSC. Walmart, NAPA, etc. Start and cycle the 3pt a couple times. If no visual sign of water contamination you are done. If there is still some water in the system repeat as above.

AFAIK all of those tractors had a pickup screen in the sump and nothing else. If yours is missing replace it.

Dan
Dan,
Thanks for your input. I’ve probably filled and drained it 4 times (twice after purchasing and twice to split the tractor. The most recent one doesn’t show signs of water. Cross this off my list. Now if I could get the new clutch to disengage 😡.
I’ll add the screens too.

Scott
 

IdahoNative

Active member

Equipment
Kubota B7100D 4x4, non-HST, FEL 1630
Jan 12, 2022
118
46
28
Florida, central
The dark stuff is likely coming off all the 'walls' and non-meshing surfaces on the sides of gears, inside tubes, etc. In other words, it's not exactly critical that you get it all out, because it's not like its coming from the actual wear surfaces between the gears, in the pump, shaft bearings etc. However, this is the reason why some people say 'don't do a flush on really old fluid, you'll pick up all the stuff off the walls and put it back into circulation'. Well, they say that about cars, anyway. I don't really agree with it except to say that if you're GOING to put a new detergent fluid that is supposed to carry that stuff in suspension, you probably should keep flushing it until it stops coming back dirty, otherwise what they say is somewhat true. But usually that's said in regards to automatic transmissions which are far far pickier than manuals. With manuals practically the only concern is the compatibility of the fluid with the material on the synchronizers, but guess what you don't have any! You can even find examples in the car world where the manufacturer recommended ATF, motor oil. and gear oil for the same manual trans, depending on what year of the service manual you looked it up in! Oh, and different fluid capacities too. SAME TRANS!

My suggestion though is to use the cheapest fluid you can get your hands on to do these flushes, even if it isn't tractor fluid. ATF or motor oil would also be ok. The main thing is that you get the correct fluid in it the last time around, IF it's even picky, which i don't think a b7100 is.

So i guess that's a lot of words that amounts to, either call it good and stop, or keep flushing until it comes back clean (with the cheapest fluid you can get your hands on), it's up to you and neither approach is likely to hurt the machine in any noticeable way. In my opinion 'operator error' is a lot more likely to hurt an old gear trans than the difference between any number of oils, or whether the fluid is perfectly clear or not.
there is no such thing as cheap fluid anymore 😁
 
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Pau7220

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L3650 GST, Landpride TL250 FEL w/ Piranha, 6' King Kutter, GM1084R Finish
Aug 1, 2017
785
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Scranton, PA
Water usually enters through the shift boot. Make sure yours is in good shape.
 
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RalphVa

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Jan 19, 2020
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Charlottesville
My tractor sat for years before I purchased it. The hydraulic fluid was milky white and had water in it. I drained it overnight, replaced it the next day. I had to do this a few times to flush the old fluid out. That was expensive! BTW, mine doesn’t have ANY screens, just a hydraulic filter at pump intake. I have three questions:

To flush the system, can I simply put the lower tank line that goes to the hyd pump into a 5 gallon jug of new hydraulic fluid and place the return line into a separate 5 gallon container? I would cycle the FEL and 3 pt too.

What should hydraulic fluid look like after about 30 minutes of use? IMO, mine looks too dark. The glob in the middle is a paper I accidentally dropped.

Did all models come with hydraulic screens? Should I buy and install them?

thanks!
I'd flush with diesel, a lot less expensive. Then drain and fill with HST oil. Don't know about the screens. If it didn't have any, I would not add.
 
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GreensvilleJay

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Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
Apr 2, 2019
11,668
5,049
113
Greensville,Ontario,Canada
yeesh diesel here is $6.50 CDN for a US gallon..

might not need 'HST' oil, rather a generic 'Universal Tractor Fluid', the stuff good for everything BUT the engine ??
 
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TheOldHokie

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L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Apr 6, 2021
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Myersville, MD
windyridgefarm.us
I'd flush with diesel, a lot less expensive. Then drain and fill with HST oil. Don't know about the screens. If it didn't have any, I would not add.
All models of the B7100 had a steel mesh sump strainer (aka "filter" in the parts catalog) in the suction line, It was part of the rear banjo bolt - part number 40 in the diagram below. Kubota used this type strainer on a lot of different tractors.

Dan

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Russell King

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L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
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Austin, Texas
See this thread to answer your original question on flushing transmission

I don’t think you need to do it now though.

There may be some drain plugs low on the rear axle drives that you’re not using? On my L185 tractor there are plugs on the vertical wall on the inside of the axle that drain about a half gallon of fluid per side and it is pretty nasty looking fluid.

I use tractor supply Traveler universal fluid but never any of the 303 type fluid
 
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