Temporary power steering loss on nearly new L4060

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
1,188
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I now have about 200 hours on my L4060 HSTC which I bought a year ago. Ever since new, I notice at times when rapidly steering (say trying to turn around in a tight spot...turn hard one direction and pull forward, then rapidly turn hard the other way and back up)...it suddenly feels like you lose power steering for a moment, like it can't keep up. It's much more prevalent with the loader on then off. It basically feels like there isn't enough power steering hydraulic flow. Do these "luxury" tractors have weak power steering? Anyone else experience this? (Keep in mind this occurs while I am mowing at full throttle)
 

SDT

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multiple and various
Apr 15, 2018
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SE, IN
I now have about 200 hours on my L4060 HSTC which I bought a year ago. Ever since new, I notice at times when rapidly steering (say trying to turn around in a tight spot...turn hard one direction and pull forward, then rapidly turn hard the other way and back up)...it suddenly feels like you lose power steering for a moment, like it can't keep up. It's much more prevalent with the loader on then off. It basically feels like there isn't enough power steering hydraulic flow. Do these "luxury" tractors have weak power steering? Anyone else experience this? (Keep in mind this occurs while I am mowing at full throttle)
I have similar issues with my L6060. I routinely "out run" the PS system when maneuvering rapidly and have simply learned to live with it.

Relatedly, my biggest complaint with my L6060 is that the steering is too slow. I simply cannot crank it fast enough in many situations, whether or not I have "out run" the pump.

SDT
 
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troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
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Thanks SDT. The power steering on my previous MX4800 was night and day better. I wondered if the lesser horsepower tractors in the Grand L 60 range had the problem but not the higher HP models. Apparently not. Kind of a shame on a very nice tractor; I will also live with it.
 

skeets

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BX 2360 /B2601
Oct 2, 2009
14,558
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SW Pa
I hve to ask, have either of you changes your hydro filters or cleaned the screens? Reason I ask, a friend had an older Ford, that would do something like that. Tracking it down, he found the filter screen was pretty clogged, he changed the filter but never cleaned the screen. Once it was cleaned it, the problem went away,,, just a thought
 

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
1,188
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I hve to ask, have either of you changes your hydro filters or cleaned the screens? Reason I ask, a friend had an older Ford, that would do something like that. Tracking it down, he found the filter screen was pretty clogged, he changed the filter but never cleaned the screen. Once it was cleaned it, the problem went away,,, just a thought
It has done it to me since brand new, but to answer your question...yes. My tractor was subjected to the recent Kubota recall for an improperly tightened HST bolt; during the procedure the dealer replaced both hydraulic filters at my request. No change in power steering.
 

SDT

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multiple and various
Apr 15, 2018
3,255
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I hve to ask, have either of you changes your hydro filters or cleaned the screens? Reason I ask, a friend had an older Ford, that would do something like that. Tracking it down, he found the filter screen was pretty clogged, he changed the filter but never cleaned the screen. Once it was cleaned it, the problem went away,,, just a thought
Same here. Same symptoms since the day I bought it home.

Filters were changed at 50 hours and again at about 170 hours as was the oil. L6060 now has about 180 hours.

It's not the filters.

SDT
 

dgtvrpepair

Member

Equipment
L4760HSTC RTV-X1100c ZD1211L-72
Feb 10, 2020
47
23
8
Morrilton AR United States
Interesting!
I have had the same problem, I have been dealing with it for years. Mine is l4760 hydro- same hydraulics as yours. Had it to dealer many times and nothing has repaired it. I purchased the service manual to try and figure it out myself. The service manual is wrong. The hydraulics in it are for the l3560 and the l4060 and up are plumbed different. I found the parts diagrams on messick's by my model. You have to register to see them. If you follow the output of the pump through the steering controller the return fluid tees and goes through cooler back to tank or can bypass cooler and go back to suction of pump top metal line that is by large suction on pump. I found that when demand was needed it was sucking the oil out of the steering controller causing loss of steering when going forward to reverse and try to steer. It got really bad after mowing for an hour or 2, I plugged off the return of pipe 040 to return of pump. now oil goes from pump to steering controller out to oil cooler then returns to tank. Now it can't bypass cooler and keep heating same oil over and over, and it can't be pulled out of controller backward. No more loss of steering and better yet stall guard works so much smoother. Before in stall guard and auto hydrostat the tractor rpm would drop slightly and it would drop to low range fast and back fast with very little rpm change, Now when tractor rpm drops close to 540 when mowing tall grass, speed slows down and the rpm stays at 540 and doesn't drop ranges as rpm builds back above 540 the speed starts going back up. It will still drop ranges as it should just not so fast. I can now change directions as fast as I want and no loss of steering. I have ran it 8 hours this way. I explained this to my dealer and they are lost. It is a definite design flaw.
 
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troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
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I have had the same problem, I have been dealing with it for years. Mine is l4760 hydro- same hydraulics as yours. Had it to dealer many times and nothing has repaired it. I purchased the service manual to try and figure it out myself. The service manual is wrong. The hydraulics in it are for the l3560 and the l4060 and up are plumbed different. I found the parts diagrams on messick's by my model. You have to register to see them. If you follow the output of the pump through the steering controller the return fluid tees and goes through cooler back to tank or can bypass cooler and go back to suction of pump top metal line that is by large suction on pump. I found that when demand was needed it was sucking the oil out of the steering controller causing loss of steering when going forward to reverse and try to steer. It got really bad after mowing for an hour or 2, I plugged off the return of pipe 040 to return of pump. now oil goes from pump to steering controller out to oil cooler then returns to tank. Now it can't bypass cooler and keep heating same oil over and over, and it can't be pulled out of controller backward. No more loss of steering and better yet stall guard works so much smoother. Before in stall guard and auto hydrostat the tractor rpm would drop slightly and it would drop to low range fast and back fast with very little rpm change, Now when tractor rpm drops close to 540 when mowing tall grass, speed slows down and the rpm stays at 540 and doesn't drop ranges as rpm builds back above 540 the speed starts going back up. It will still drop ranges as it should just not so fast. I can now change directions as fast as I want and no loss of steering. I have ran it 8 hours this way. I explained this to my dealer and they are lost. It is a definite design flaw.
Are you saying your L4760 is plumbed like an L3501?
Is the L4060 plumbed like the higher HP models or like the 3560?

I've had this occur when simply trying to steer quickly, without changing directions. It's like there isn't enough flow to the pump. On mine, stall guard seems to work fairly well as is.
 

dgtvrpepair

Member

Equipment
L4760HSTC RTV-X1100c ZD1211L-72
Feb 10, 2020
47
23
8
Morrilton AR United States
Are you saying your L4760 is plumbed like an L3501?
Is the L4060 plumbed like the higher HP models or like the 3560?

I've had this occur when simply trying to steer quickly, without changing directions. It's like there isn't enough flow to the pump. On mine, stall guard seems to work fairly well as is.
The l3560hstc is different. My service literature both on cd and paper for my L4760hstc show's to be the same as the L3560hstc and they are different. The L4060hstc L4760Hstc L5460hstc and L6060hstc are all plumbed the same. Mine acted exactly as you described it, but would get even worse to almost complete loss of steering after mowing at full throttle for 2-3 hours. Stall guard and auto range seemed to work fine to me before but now work way better yet.
 
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troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
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The l3560hstc is different. My service literature both on cd and paper for my L4760hstc show's to be the same as the L3560hstc and they are different. The L4060hstc L4760Hstc L5460hstc and L6060hstc are all plumbed the same. Mine acted exactly as you described it, but would get even worse to almost complete loss of steering after mowing at full throttle for 2-3 hours. Stall guard and auto range seemed to work fine to me before but now work way better yet.
Thanks for providing this update. Mine is still under warranty but I would definitely contemplate making this change. My tractor is primarily used for flail mowing tall grass, and does bog down occasionally. I don't use auto range change - just flip the paddle myself when necessary. I found the auto feature to be too frequent and too abrupt.
 

dgtvrpepair

Member

Equipment
L4760HSTC RTV-X1100c ZD1211L-72
Feb 10, 2020
47
23
8
Morrilton AR United States
Thanks for providing this update. Mine is still under warranty but I would definitely contemplate making this change. My tractor is primarily used for flail mowing tall grass, and does bog down occasionally. I don't use auto range change - just flip the paddle myself when necessary. I found the auto feature to be too frequent and too abrupt.
I run flail mower myself, best mower ever. Many people have never seen one here in Arkansas. The auto feature will not kick in now unless you really bog it below 540 pto and it isn't near as abrupt.
 

troverman

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MX6000 HSTC; 2020 Kubota Z421KW-54 zero turn mower
Jun 9, 2015
1,188
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NH
I run flail mower myself, best mower ever. Many people have never seen one here in Arkansas. The auto feature will not kick in now unless you really bog it below 540 pto and it isn't near as abrupt.
I like my flail mowers as well. They can be fragile hitting certain things, but the cut quality is much nicer than a brush hog and they are more compact.
 

ruger1980

Active member

Equipment
L4310 w/La682, L225
Oct 25, 2020
395
145
43
CNY
I have had the same problem, I have been dealing with it for years. Mine is l4760 hydro- same hydraulics as yours. Had it to dealer many times and nothing has repaired it. I purchased the service manual to try and figure it out myself. The service manual is wrong. The hydraulics in it are for the l3560 and the l4060 and up are plumbed different. I found the parts diagrams on messick's by my model. You have to register to see them. If you follow the output of the pump through the steering controller the return fluid tees and goes through cooler back to tank or can bypass cooler and go back to suction of pump top metal line that is by large suction on pump. I found that when demand was needed it was sucking the oil out of the steering controller causing loss of steering when going forward to reverse and try to steer. It got really bad after mowing for an hour or 2, I plugged off the return of pipe 040 to return of pump. now oil goes from pump to steering controller out to oil cooler then returns to tank. Now it can't bypass cooler and keep heating same oil over and over, and it can't be pulled out of controller backward. No more loss of steering and better yet stall guard works so much smoother. Before in stall guard and auto hydrostat the tractor rpm would drop slightly and it would drop to low range fast and back fast with very little rpm change, Now when tractor rpm drops close to 540 when mowing tall grass, speed slows down and the rpm stays at 540 and doesn't drop ranges as rpm builds back above 540 the speed starts going back up. It will still drop ranges as it should just not so fast. I can now change directions as fast as I want and no loss of steering. I have ran it 8 hours this way. I explained this to my dealer and they are lost. It is a definite design flaw.
The intended flow of oil through the cooler is not as you describe. It should exit the top of the HST case and flow through the cooler and to the inlet of the hyd. pump. This is called case drain oil and is generally has the most heat of any compartment or oil in the system. For this reason I would not recommend this modification.
The way you have modified the circuit you have return flow from the steering controller now going through the cooler to the HST case and out the case relief valve into the transmission case or sump. This will raise oil temps and possibly degrade the oil sooner then normal
 

Lakebuster

New member

Equipment
GrandL5040, RTV1100, ZTR331, B2601
Jul 1, 2021
22
5
3
SW Louisiana
I now have about 200 hours on my L4060 HSTC which I bought a year ago. Ever since new, I notice at times when rapidly steering (say trying to turn around in a tight spot...turn hard one direction and pull forward, then rapidly turn hard the other way and back up)...it suddenly feels like you lose power steering for a moment, like it can't keep up. It's much more prevalent with the loader on then off. It basically feels like there isn't enough power steering hydraulic flow. Do these "luxury" tractors have weak power steering? Anyone else experience this? (Keep in mind this occurs while I am mowing at full throttle)
I have a L4740 and was moving a lot of dirt yesterday and did notice this. My RPM's where kinda low when this happened.
 

eipo

Active member

Equipment
L4060
Dec 1, 2015
693
83
28
MI
Huh, some things must not change. My new 4060 with just over 50 hours now has the same steering issue. Sometimes it works fine, sometimes it acts as if the power steering has gone out.
 

sheepfarmer

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Lifetime Member

Equipment
L3560, B2650, Gator, Ingersoll mower
Nov 14, 2014
4,449
677
113
MidMichigan
Huh, some things must not change. My new 4060 with just over 50 hours now has the same steering issue. Sometimes it works fine, sometimes it acts as if the power steering has gone out.
So you feel resistance in the steering wheel? Wonder what the difference in design between the 3560 and 4060 is, as I don’t think I’ve ever had that happen.
 

dgtvrpepair

Member

Equipment
L4760HSTC RTV-X1100c ZD1211L-72
Feb 10, 2020
47
23
8
Morrilton AR United States
So you feel resistance in the steering wheel? Wonder what the difference in design between the 3560 and 4060 is, as I don’t think I’ve ever had that happen.
I haven't seen a L3560 hst in person. It could possibly have the same problem also. I pulled up hydraulic diagrams on Messick's for the L3560 and it shows it is the same as the l4060 and all 60 series. My service literature in both the hard copy and the disk show the L3560 to have the ASSY VALVE,CONTROL on top of the hydraulic pump. The ASSY Valve,control on my l4760 is mounted on the right side near rear axle. If you can take a picture of your hydraulic pump I could tell you if it is the same way.
 

eipo

Active member

Equipment
L4060
Dec 1, 2015
693
83
28
MI
So you feel resistance in the steering wheel? Wonder what the difference in design between the 3560 and 4060 is, as I don’t think I’ve ever had that happen.
Yes, acts like Ive got a bucket full of something heavy. Sometimes it gets 'notchy', other times it works perfectly.

I generally try not to turn the wheel unless I'm moving anyway, so I haven't given it any consideration. Its still under warranty.
 

dgtvrpepair

Member

Equipment
L4760HSTC RTV-X1100c ZD1211L-72
Feb 10, 2020
47
23
8
Morrilton AR United States
Yes, acts like Ive got a bucket full of something heavy. Sometimes it gets 'notchy', other times it works perfectly.

I generally try not to turn the wheel unless I'm moving anyway, so I haven't given it any consideration. Its still under warranty.
Please search L6060 steering loss and read through all of that. The correct fix as far as I can tell has details on the best way to fix this. The way I had it before is not the best way to do this after talking in the forum with 2 others. I also posted some images of it.
 
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