NX 5010HST Cab reverse intermittent and jerky

[YLee Kioti]

Have you gone to the dealer you bought the tractor from and asked to see what brand they use to service the machines?
I did and they used a local branded fluid from a Texas distributor.

The jerking was not as prominent as many mentioned here but has almost gone away with the third change out using Kubota's fluid.
Before that used NAPA's Coastal brand full synthetic on the second change out. Fifty hours on Kubota's fluid and do not see/feel any performance difference.

Now that's it's about 104* out here and after a few hours the machine may have a jerky response... when first engaging to travel reverse.

Since each brand has different additive packages.....maybe comparing the brand your dealer uses versus others up for consideration will help in deciding which to go with.....
And I did my first fluid change at 200 hours to remove fines from hyd. system,....but that's just me OCD to fault......(yeah I don't like it either....lol)

 

[TN8Man]

Have you gone to the dealer you bought the tractor from and asked to see what brand they use to service the machines?
I did and they used a local branded fluid from a Texas distributor.

The jerking was not as prominent as many mentioned here but has almost gone away with the third change out using Kubota's fluid.
Before that used NAPA's Coastal brand full synthetic on the second change out. Fifty hours on Kubota's fluid and do not see/feel any performance difference.

Now that's it's about 104* out here and after a few hours the machine may have a jerky response... when first engaging to travel reverse.

Since each brand has different additive packages.....maybe comparing the brand your dealer uses versus others up for consideration will help in deciding which to go with.....
And I did my first fluid change at 200 hours to remove fines from hyd. system,....but that's just me OCD to fault......(yeah I don't like it either....lol)

I'm bringing my tractor back in next week so I will get the fluid info then.

 

[justman777]

I'm bringing my tractor back in next week so I will get the fluid info then.

I'm going to put some Mobile 424 in mine and see what it does.

 

[TN8Man]

I'm going to put some Mobile 424 in mine and see what it does.

I will probably do the same once I figure out the best fluid for my application.

I did discover my cooling fan belt was loose, more than twice the spec. I could turn the fan by hand with little pressure. Not sure how much difference this will make but it needed to be adjusted.

 

[justman777]

Changed out my fluid to Mobile 424, and didn't make a lick of difference. At least now I know I have good fluid!

I managed to take a video of the aeration in my hydro reservoir. You can see the video here. There's no sound.

I start the tractor about 10 seconds into the video, and the aeration starts within seconds after. It looks pretty cool, but I don't think it's supposed to do that.

 

[Citydude]

Changed out my fluid to Mobile 424, and didn't make a lick of difference. At least now I know I have good fluid!

I managed to take a video of the aeration in my hydro reservoir. You can see the video here. There's no sound.

I start the tractor about 10 seconds into the video, and the aeration starts within seconds after. It looks pretty cool, but I don't think it's supposed to do that.

Good luck. This has to be madding for you. But glad you got the root cause figured out. Leak in the suction side.

 

[justman777]

Good luck. This has to be madding for you. But glad you got the root cause figured out. Leak in the suction side.

Maddening, yes. At this point, I'm not sure it's a suction side leak as the fluid returns aerated to the sump within seconds of me starting the tractor. It seems like it should take longer to make it through the pump and return. I know a suction side leak is the most likely culprit, but we've changed out just about every suction side component that may have caused a leak---o-rings, filters, filter housing, pump, clamps, etc.

 

[TN8Man]

I did finally got some answers from a hydraulics expert. For the life of me I could not find the answer to "What is the maximum operating temperature for a tractors hydraulic fluid before it starts oxidation and degradation?". The answer is 180F. I was measuring 209F on the outside metal below the the hydro fill port when my tractor started malfunctioning. (loss of reverse travel and hydro system pulses/jerks).

I was also told the Aeration (foaming or frothy) hydro fluid could be the cause of the hydro fluid overheating. And Aeration is typically caused by the tank too low on fluid or a suction side leak.

Other causes of hydro fluid overheating are:
Defective cooling
Oil level too low
Wrong bypass valve setting
Malfunction of other valves
Volumetric efficiency loss of pump due to wear, etc.
Internal leakage across actuators and valves
And many more.

So in my case it's the aeration that is probably causing the overheating and the malfunctioning of hydraulic systems.

 

[dusty3030]

Looking at justman777's video, the bubbles form quickly.
So which side of the hydraulic circuit is it coming from?

I had my heating issue with the factory third function valve and it's undersized power beyond and return to tank hoses and fittings.
I took apart the rear remote valve and I don't see anything in there that would restrict flow, it appears to be correctly sized. What I haven't inspected or taken apart is the the three point hitch valve area which would be the last place in that circuit.

The other place it could be coming from is the power steering / HST side of the circuit. In that case I really don't know how you could really inspect things.

What I wish I did know was what is the split in flow between the two sides? I can find the total flow gpm but not the split. Anyone know?

 

[justman777]

Looking at justman777's video, the bubbles form quickly.
So which side of the hydraulic circuit is it coming from?

I had my heating issue with the factory third function valve and it's undersized power beyond and return to tank hoses and fittings.
I took apart the rear remote valve and I don't see anything in there that would restrict flow, it appears to be correctly sized. What I haven't inspected or taken apart is the the three point hitch valve area which would be the last place in that circuit.

The other place it could be coming from is the power steering / HST side of the circuit. In that case I really don't know how you could really inspect things.

What I wish I did know was what is the split in flow between the two sides? I can find the total flow gpm but not the split. Anyone know?

The split in the flow between the loader functions/3 point lift and the HST/Steering appears to be the pump. The hydro pump is a dual pump. See the flow routing diagram on the thread here.

 

[dusty3030]

I know the pump is split- but what is the flow rating for each leg? Usually the power steering/ hst is a lower portion of the total gallons per minute.

 

[dusty3030]

Both hard lines coming out of the pump are the same size. One goes to loader valve and the other to the modulate valve.
The power beyond out of the loader valve is a 1/2 “ line to your rear remote.
The line from the modulate valve to the power steering valve is only a 3/8” line. The line to the pro clutch is even smaller. So big line into the valve and a smaller line out that has to feed the power steering, goes through the cooler then feeds the HST. What is perplexing is that the steel line jumps back up in size between the cooler and hst filter and is a larger diameter line from the hst filter into the hst unit. So is the hst needing more fluid than the 3/8 feeder can provide causing aeration? How much flow is the pump trying to pump through the 3/8 power steering line?

 

[dusty3030]

Hard line into modulate valve larger than the 3/8 coming out. Shows both hardliners out of pump the same size. Hard line that drops down from cooler to below the alternator hooks up to a larger diameter hard line that goes into the hst filter.

 

[TN8Man]

Here is a good article in aeration and cavitation.

Aeration vs. cavitation in hydraulic system design

 

[Robin Veerman]

That is indeed a good article above. I use Amsoil in my HST and I'm extremely happy with it. Very smooth operation of the HST whether it be in the summer's heat or winter's cold. Read the link in the following article and see if it meets the extreme requirements that HST transmissions require. Dutchy Synthetic Tractor Hydraulic/Transmission Oil SAE 5W-3 ATH - AMSOIL

 

[TN8Man]

It shows viscosity of 10.1 cSt @ 100°C. That's better than most Ive seen and one of my key concerns.

 

[YLee Kioti]

That is indeed a good article above. I use Amsoil in my HST and I'm extremely happy with it. Very smooth operation of the HST whether it be in the summer's heat or winter's cold. Read the link in the following article and see if it meets the extreme requirements that HST transmissions require. Dutchy Synthetic Tractor Hydraulic/Transmission Oil SAE 5W-3 ATH - AMSOIL

I used the product in the CK4010HST, as it was a 5 gallon capacity. But at 12 gallons that is just a bit way to steep.
So for now using Kubota's hyd oil. They are 14 miles away and should be good for any tractor. So far 60+ hours and seems to operate just as well as the NAPA Coastal full synthetic.
Course been to dry to cut much and property is now in maintenance mode and so the land clearing phase is done.....

Sure would go a long way if Kioti, or any mfg. for that matter would be willing to be proactive when a customer has a issue that is out of the ordinary.

 

[TN8Man]

Update on my NX50HSTcab failure mode (intermittent loss of reverse, jerky hydraulics, excess heat in HST >200F):

Glad to report my tractor seems to be fixed, finally. The local shop cracked open the HST and replaced solenoids. Apparently these solenoids were known issues and Kioti recently changed suppliers.

I have used the tractor under the same conditions where it failed (except ambient temp is now in the upper 60's instead of upper 80's) and it has not failed and the temp near the hydraulic fill port is now ~150F instead of well over 200F. I even used the big bush hog with no issues.

Hopefully the problem is gone for good.

 

[YLee Kioti]

Thanks for this update.....it seems to be a trend about mfg. responding slowly to known issues and never acknowledge them.
Back in the day my 7.3l PowerStroke had a camshaft sensor issue known to fail by shutting down engine.
The diesel boards were lit up for months on this topic.
Many of us flooded the NHSTA and recorded our issues......mine died as I crossed a set of tracks.......uh....yea...!!!......

Since I'm sub'd to this thread is I have any issues I'll share this with my dealer.....who has a track record of excellent service and responses....

Give us a 25/50 hour or so update......if you remember that is....lol....

 

[TN8Man]

Thanks for this update.....it seems to be a trend about mfg. responding slowly to known issues and never acknowledge them.
Back in the day my 7.3l PowerStroke had a camshaft sensor issue known to fail by shutting down engine.
The diesel boards were lit up for months on this topic.
Many of us flooded the NHSTA and recorded our issues......mine died as I crossed a set of tracks.......uh....yea...!!!......

Since I'm sub'd to this thread is I have any issues I'll share this with my dealer.....who has a track record of excellent service and responses....

Give us a 25/50 hour or so update......if you remember that is....lol....

Yep, even the shop manager did not offer up the "known issue" part until I pressed him on it. I don't think their profit margin on warranty work is as good as non warranty work.