How hot is your HST?

[Grandad4]

The MSDS chemical safety sheet for SUDT2 lists a flash point of 262 deg. F. but does not specify a boiling point. Without putting too fine a point on it, temps in the 200 range (or thereabouts ), are probably something of an indication things are getting pretty warm in there. 213 deg? Probably OK too, but time to take notice.

With my equipment, when the fluid gets really heated up, it just smells hot, the hydraulic lines are too hot to touch and I've noticed the FEL hydraulics, for example, can act a bit erratically. It took a couple hours of intense, heavy loader operation to get to that point with my Kubotas (a little one and a bigger one). After that, I figured out neither the machines nor the operator really needed to work at that pace.

 

[JackJ]

I think that you are worrying over nothing. I'll be the first to admit that I could be wrong but if you are not experiencing any problems then temperatures do not mean anything in this context.

Thanks--I suspect you're probably right. I am seeing some folks say that anything over 200F is potentially problematic, but have seen very few actual measurements. The fact that I'm not seeing any actual problems in terms of how the tractor performs hopefully means that my machine is acting normally.

 

[ehenry]

My 2001 BX22 that I inherited a couple years ago has 2150+ HARD hours on the clock and the only oil the HST/hydraulic system has ever had in it is Kubota UDT and that is with zero fins on the HST fan for over half its life. It has never failed to go to work when ever it was called upon. BTW, it now has new HST fan, under-armor and fresh cv boots and joints on it.

 

[William1]

After a few hours of running my little BX25D, using the backhoe, the hydraulic cylinders are nearly too hot to touch. I figured after the workout I was giving it, I'd of burned my hand on one, but nope, not too bad. probably about 200 degrees. Next time I run it hard for a few hours on a 100 degree day, I'll do a temp check on the trans under the seat and at a few of the fittings and see what max temps I am running.
But based on my limited knowledge of a HST and hydraulics, I'd expect a lot of heat.

 

[JackJ]

My 2001 BX22 that I inherited a couple years has 2150+ HARD hours on the clock and the only oil the HST/hydraulic system has ever had in it is Kubota UDT and that is with zero fins on the HST fan for over half its life. It has never failed to go to work when ever it was called upon. BTW, it now has new HST fan, under-armor and fresh cv boots and joints on it.

Now THAT is encouraging! I'm glad to know your machine now has a caring owner, but also glad to know that it survived the prior abuse, operating so long with no cooling fan.

 

[ehenry]

JackJ, I used the machine all day last Saturday in 85+ degree heat to move 4 to 6 foot long 18 to 20+ inch diameter pine logs from the woods from behind my house to a burn pile 100+ yards away and the only malfunction the whole day was running over not one but two rail road spikes still the plate that's used to hold the track down that was hidden in amongst the pine straw, briars and brambles. Cost me a front tire but "Fred" shook it off and kept on keepin on with a new front foot.

 

[WFM]

I guess I never really worried about how hot the HST got. When I bush hog or use the rotary cutter, I always (well 99.0%) travel in M on the shifter. So maybe going faster the air going by keeps it cooler. But the HST is loud. I try to wear ear protection if I remember.

 

[whitetiger]

I would say that depends on the dealers mind set. Some don't seem to want to carry the more expensive SUDT or SUDT2 fluid and will and have told their customers that UDT will work just fine. It probably will but the other 2 are a better grade fluid. You will always have some that will never believe or agree that synthetic performs and protects better no matter what.

I would guess it should at least have SUDT but if it was assembled out of a crate at the dealer you never know. May pay you to ask your dealer what they use. I know when I bought my L3000 it came to me with a small leak. When the service guy came to fix it he brought a gallon of UDT and said it was just as good as SUDT. My thought on that if it was just as good they would only offer one fluid.

I'll say this. I was assured my tractor came with SUDT and the Amsoil fluid I changed it to was a night and day difference. Smoother performance cold and cooler operating temps during the summer. In my opinion it's hands down a better fluid than what Kubota offers.

Kubota equipment that is shipped in a crate is already filled with all fluids.

 

[JackJ]

Rekindling (no pun intended) this thread since today I saw a new high temp on my HST: 222F

This was after about 90 mins of mowing medium tall grass with my 48" deck on a moderately hilly lawn with 85F ambient temps. I was in low range, 3100 RPM, pedal most or all the way down most of the time. I could smell that things were a little hotter than typical, but no other symptoms. Though this is probably normal, I'd still love to see some temps measured (per post 17 in this thread) by other BX owners in similar conditions to verify.

 

[tcrote5516]

You're fine. I know someone stated earlier in the thread the flash point was in the 260 degree range but that number is not correct. The flash point is at 390 (see link below and go to page 5).

http://www.kubota.com/assets/safety... GA KU20005 United States (GHS) - English.pdf

222 degrees is nothing to worry about, heck many cars run that temp in coolant and that's not even a "working" fluid in that application. Engine oil temps should run north of 230 degrees to be efficient and again, that's not a "working" fluid. HST transmissions will create significant heat, PUT THE IR GUN DOWN and DON'T WORRY!

 

[JackJ]

You're fine. I know someone stated earlier in the thread the flash point was in the 260 degree range but that number is not correct. The flash point is at 390 (see link below and go to page 5).

http://www.kubota.com/assets/safety... GA KU20005 United States (GHS) - English.pdf

Thanks for the reassurance! Though I was pretty concerned months ago when first researching this, with a brand new tractor, and reading that anything over 200F could be a problem. Seeing that post about the flashpoint being just 262F certainly didn't put my mind at ease.

But my transmission fluid still looks and smells like new, there have been no related issues, and I'm not working it exceptionally hard. So yes, I'm thinking mine is behaving completely normally.

But I'm still curious what temps other BX owners are seeing with an infrared gun at the pump output, hoping for a baseline normal range so that we can establish what constitutes an actual problem with HST temp.

 

[JackJ]

So after posting the above, the MSDS pdf's finally loaded for me. And it looks like the published flashpoint for SUDT2 actually is 262F:
http://www.kubota.com/assets/safety/pdf/msds/70000-40202%20KUBOTA%20SUPER%20UDT2%202_2.5%20GA%20000000000000735542%20United%20States%20(GHS)%20-%20English.pdf (page 7)

They describe it as a "calculated flash point."

The 390F figure cited above appears to be for plain old Kubota UDT, not the newer and presumably superior SUDT2. I'm not going to take the time to research flash points on other hydraulic oils at the moment, but 262F does seem to be quite low. Given that my apparently normal running tractor is getting to within 40F of that figure when not being pushed all that hard, I suspect the number is wrong, but it'd be nice to know for certain.

 

[Grandad4]

Must apologize for putting out that bad 260 deg. flash point number. It did come from what was labelled an MSDS sheet for SUDT2, which I took in good faith as legit, although I can't find it currently. My bad. And I agree with the advice here that warm and even hot temps are the norm when working these tractors.

 

[JackJ]

Must apologize for putting out that bad 260 deg. flash point number.

No, no: You got it right. That is indeed the published "calculated flash point" for SUDT2, with the link two posts up. It may be a "bad number" but it is the published number on a document hosted at kubota.com. If I get time later maybe I'll contact them about it.

 

[Grandad4]

Thanks for the correction. That does indeed seem like a really low number, doesn't it? Have never heard of an incident involving ignition of SUDT2, and you have to know there have been countless tractors whose drivetrains have gotten really hot.