hydraulic fluid level; sight glass ... beginner error

betz

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Jun 23, 2021
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My problem: the manual clearly states NOT to run the tractor with fluid below the lowest aspect of the sight glass. It also indicates that a fluid level anywhere between the bottom and top of the sight glass is operable. What the manual does not speak to, is how to deal with a fluid level above the sight glass... ?

My question: Is it safe to operate the tractor if the hydraulic fluid level is above the sight glass?

Here is what happened: I bought a new tractor from the dealer. After reading the manual, I go out to do a "daily inspection" and notice the sight glass is solid, opaque white. Not amber, not off-white, but solid white. I see no fluid level. There is no small bubble at the top of the glass. My first thought is that water is in the system and has steamed/foamed and covered the inside of the glass. I contact the dealer and I am told to drain and re-fill the system.

I did not drain anything. I got on YouTube and looked at three other L2501 sight glasses and they all had contrasting oil against a white background, with a visible fluid level. [Ahhh! a white background!] I used a flash light to better look for any indication of fluid now that I understand there is a contrasting white background in the glass. At this point, I am convinced the fluid level is low; and that I am looking at a white colored background, with no fluid in front of it.

I bought some UDT-2 thinking I would add one or two quarts and the level would become visible... Nope, this did not happen. So clean and white was the background, without a hint of amber, I was convinced I was looking at the empty sight glass, no fluid. Checking as I went, I added little by little, check all the way, until I had added the gallon and still could not see a fluid level.

At this point, I drove the front axel up onto ramps--effectively lifting the front end by about eight inches--and lo, and behold, a fluid line level was visible in the sight glass (maybe 1/4 way down from the top).

Okay. Now I realize I've got more than enough fluid. To drain excess? Or, leave it because it isn't hurting anything?

Please advise. Does anyone know if I'm at risk if I leave it as-is?
 

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Roadworthy

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I'd run it as is. If you are over filled you are just barely over filled. When you do your fifty hour filter change you will lose anywhere from a little to a lot of fluid depending on how you do it. It is VERY difficult to see the clear fluid against the white background. Congratulations on seeing the level at all. I added John Deere hydraulic fluid dye to my L2501. Kubota told me they will not cover any damage caused by the dye however my local mechanic checked with Kubota. He then told me the dye won't cause any harm according to Kubota.
 
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RCW

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My little BX "burped" when new. After an hour of use, there was nothing on the dipstick. I freaked at the time. Probably just some air. It's not uncommon.

Took a quart + to refill, but it's a BX, so smaller tractor. My dealer gave me a gallon of SUDT2 to accommodate, and personally delivered to my house... :cool:

I'm not familiar with an L2501, but assume HST? Definitely don't want to run low on fluid.

You are overfilled by a little bit. Keep an eye on the sight glass; it may drop with some time/use due to air. Also, all of them have some sort of vent to the atmosphere. Keep an eye on the vent in case it spews some fluid out when it gets hot.

HST do get hot, and fluid can be ambient temperature plus 100 degrees....it's summer after all. If it does spit from the vent, drain a couple quarts.

Otherwise, I'm with Roadworthy. just with some qualifications....

Enjoy your tractor!
 
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betz

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... Otherwise, I'm with Roadworthy. just with some qualifications....

Enjoy your tractor!
thank you! this is my first hydraulic system. I appreciate your input. [If anyone from Kabota is reading this, a few words in the manual to cover this situation might benefit more than a few folks]
 

Fordtech86

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I would drain it to the proper level. Over filling it can cause it to aerate the fluid and it will cause lack of lubrication and could push it out the vent while you are running it. I don’t deal with tractors, but you are at least a gallon over ful, seems like a lot. Clean really good around the drain plug area and you can likely save the fluid if drained into a clean jug. A fluid extractor thru the rear fill plug would work too if available.
 
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old and tired

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L2800 HST; 2005; R4
I don't know how different your L2501 is from my L2800 but I run extra hydraulic oil (over the sight glass) for 600 hours now with no issue. It's a holding tank / cooling tank as it was explained to me.

My model 2005, actually had a product improvement bulletin which submerged the ratching CAMS in hydraulic oil by adding an extra gallon and a half (along with a dipstick, to check the level).
 
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betz

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Rocky Mountains
... I run extra hydraulic oil (over the sight glass) for 600 hours now with no issue. ...
... product improvement bulletin which submerged the ratching CAMS in hydraulic oil by adding an extra gallon and a half ...
Wow. Clearly, much to consider; and I very much appreciate the thoughtful response!!
 
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Nicfin36

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The L2501 sight glass is VERY sensitive on anything but perfectly level ground. My fluid pretty much covers the glass most of the time. I can sometimes see the fluid line near the top depending where I am parked. Other times, the level shows even lower if the tractor is tilted slightly to one side. I always park my tractor where the back end sits slightly lower and the fluid covers the glass at that parking spot.

If I recall correctly, I don't think it takes very much fluid to go from half the sight glass being visible to appearing overfilled. I think that is how it worked out when I changed my fluid at 50 hours. I incrementally checked my fluid and it was a bit low on the sight glass. I added a bit more, and bam, it was at the top of the glass. Since I knew it was not a significant amount of oil I added, I just left it as/is.
 

Fordtech86

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Maybe I read too far into it....the tractor was already overful? (Who knows how much?) Then OP added another gallon?
 

betz

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Jun 23, 2021
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A fluid extractor thru the rear fill plug would work too if available.
To be safe... I think I will do this, and use a hose through the fill port in back to siphon level back down to sight glass. Thanks for the suggestion. (I am just a little embarrassed I did not think of this, myself. I was ready to crawl under and back out a plug)

It sounds like a little over isn't likely to hurt anything; but, truth is... because it was already over full when I started adding more; and because there is no dipstick -- perhaps best to be cautious. Crazy.

Sincere thanks to all who responded!
 
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85Hokie

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Maybe I read too far into it....the tractor was already overfull? (Who knows how much?) Then OP added another gallon?
That is what I read too! A gallon more??
 
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GeoHorn

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YES!…. SIPHON or pump out the excess. You can save the fluid right back into the new bottle of it for future use.

 
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Pawnee

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I love the tractor but that sight glass is too small. i have one on my motorcycle which is super easy to use because it's 30mm across and the oil is a good contrast with the background.
It's been 3.4 hours now and I've finally seen the oil level for the first time today. If the oil was a colour it would be fine as well.
 

usgroupie

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Kubota L2800 HST
Jul 2, 2022
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I have 2005 Kubota L2800 HST. With the hydraulic fluid showing at ½ in the sight glass, I used a wooden dowel “dip stick” inserted into the fill opening and probed down vertically until I hit bottom and the fluid level is 6" on the dip stick. Make sure the dip stick goes all the way to the bottom of the tranny case, as there is a kind of ledge and you might think you went to the lowest point, but didn’t. Just probe around.
 

aaluck

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This thread really poses a bigger question.... to ME anyway.

Why don't they just use a dipstick? I HATE that bubble. Its useless. You cannot see anything unless its dead center full.
 

jimh406

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This thread really poses a bigger question.... to ME anyway.

Why don't they just use a dipstick? I HATE that bubble. Its useless. You cannot see anything unless its dead center full.
I hate the sightglass on everything. I used to have a BMW motorcycle that I had one complaint with, the sightglass to check the oil. Yeah, I know you can put dye the fluid to check it easier, but seems dumb to make it this hard to check hydraulic fluid.

I think it must mean the level isn’t that critical. Fwiw, I found the BMW motorcycle wasn’t. Jury is still out on my L2501HST, 17 months and counting.
 
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RalphVa

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I had this problem on the JD 2025R that has a round sight glass. I just put a clean stick into the fill hole and then measured how far down the fluid level was. Had enough head space.

At 400 hour change, I had the wife there to spot the level. Filled it to half on the sight glass.

I like dip sticks. Even with them, you need to dip and then put onto a paper towel to see where the level is, e.g. where the oil goes into the towel.
 

Dieseldonato

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The sight glass is an "improvement" from the older level plugs, although you know right where you stand with the level plugs, if it's too full it will drain itself, lol.