L3650 trans fluid

aemsee

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G5200
Jul 27, 2021
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Fayette New York
Bought this 3650 recently. Have been accumulating fluids and filters. Could not see through sight glass, so ordered one of those as well. Thought the glass was clouded over.
Nope. That wasn't it. The fluid is milky..and WAY over full. Hopefully changing out filters and fluid will remedy the intermittently reluctant glide shift shuttle valve.
I would like to flush it out, but not at the price of the UDT fluid. Thoughts on refilling it with cheaper fluid just to flush it, before filling with the UDT? I do not see any sparklies in it. 79627ee8-2425-4a94-9519-58fbcfc7c28c.jpg fd03fd54-359e-4ef2-8804-6a1c6af3ee1e.jpg
 

Russell King

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If I am not mistaken that is still “mostly“ a gear driven tractor. If you wanted to flush it you could use some cheaper fluid like Traveler UTTF which is equivalent to UDT (but not UDT2 or SUDT2).

But if you just replace the fluid then the new fluid will dilute any contaminated fluid and using the tractor harder will evaporate off the water. If using SUDT2 then that will hold the water in suspension well.

I assume you are at least covering the tractor if you leave it outside for storage. If not, that could be where the water is coming from split leaking seals on top of the trans case.
 

North Idaho Wolfman

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So I take it you have a GST.
Elaborate more on the reluctant shifting.
FYI: I can tell you just about every square inch of the inside of the transmision and GST control on thhat unit. I had to go through mine quite a few times when i got it to get it fixed up properly.
 

aemsee

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G5200
Jul 27, 2021
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Fayette New York
So I take it you have a GST.
Elaborate more on the reluctant shifting.
FYI: I can tell you just about every square inch of the inside of the transmision and GST control on thhat unit. I had to go through mine quite a few times when i got it to get it fixed up properly.
sometimes shifting between forward and reverse I need to move the lever a couple of times before it starts to move. That is really the only thing I have noticed
 

aemsee

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G5200
Jul 27, 2021
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Fayette New York
If I am not mistaken that is still “mostly“ a gear driven tractor. If you wanted to flush it you could use some cheaper fluid like Traveler UTTF which is equivalent to UDT (but not UDT2 or SUDT2).

But if you just replace the fluid then the new fluid will dilute any contaminated fluid and using the tractor harder will evaporate off the water. If using SUDT2 then that will hold the water in suspension well.

I assume you are at least covering the tractor if you leave it outside for storage. If not, that could be where the water is coming from split leaking seals on top of the trans case.
I have only had it a few weeks, but pretty sure it had been stored outside before I bought it. It will eventually have a home in my barn
 

North Idaho Wolfman

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A little is normal on gear change as it's not a perfect system.
but on shuttle it should be within a second or so to engage.

You next step would be to check input pressure.

Do you have the WSM (aka Service Manual)?
 

aemsee

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Jul 27, 2021
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Fayette New York
A little is normal on gear change as it's not a perfect system.
but on shuttle it should be within a second or so to engage.

You next step would be to check input pressure.

Do you have the WSM (aka Service Manual)?
Yup. Have shop manual, owners manual for tractor, owners manual for engine and just got the parts manual. I am a bit OCD. I'll do the fluid/ filter change next couple of days. See how it reacts with fresh juice. TY
 

oregontrail

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Kubota L3450
Oct 5, 2025
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Washington
Interesting yours was "WAY over-full." I just added fluid to my L3450 GST and the little gauge window showed no change, so I kept on adding. I realized too late that the yellow part was probably milky fluid sitting on top of darker fluid. I'm new to this tractor so I don't know what to expect. I plan to flush and change the hydraulic fluid but I'm waiting until I have attached a new loader to it and run it a bit, in case the loader hoses have contaminants in them. Is there any problem with running it over-full for a while?

BTW, the glass looks dirty but it's on the inside.
 

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North Idaho Wolfman

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L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
Jun 9, 2013
35,749
10,809
113
Sandpoint, ID
Interesting yours was "WAY over-full." I just added fluid to my L3450 GST and the little gauge window showed no change, so I kept on adding. I realized too late that the yellow part was probably milky fluid sitting on top of darker fluid. I'm new to this tractor so I don't know what to expect. I plan to flush and change the hydraulic fluid but I'm waiting until I have attached a new loader to it and run it a bit, in case the loader hoses have contaminants in them. Is there any problem with running it over-full for a while?

BTW, the glass looks dirty but it's on the inside.
Being a GST don't run it too long with contaminated fuild in it or you will be in for an expensive repair.
Water or air entrained fluid fill damage the clutch seals.