L1720 / L345dt Loader Operation Troubleshooting Help

[evantwheeler]

I picked up a tractor that I shouldn't have been looking at in the first place.....fixed all of the electrical issues from the previous owner/hack, and am having trouble with the hydraulics. The 1720 FEL was non-op due to issues with the external pump. I had a spare block to get hydraulics from the tractor, and cannot understand what is happening with the hydraulics. My main tractor is an L305dt, which I've had for a few years now without any trouble. For some reason, I've picked up a couple L345's thinking that I would make myself another nice tractor that I could install my backhoe onto, and its not going how I had hoped....

Anyhow, with this 345 idling, the curl cylinders want to extend with no lever input. The curl cylinders extend and retract as they should when you actuate the spool valve with the lever and the curl extend/function appears to have decent pressure/force, but the self-extension has me scratching my head. To troubleshoot, I have installed (3) separate open center two lever valve banks onto this tractor and all three exhibit the same curl cylinder extension with out lever input. I went as far as taking the hydraulic take off block and valve bank from my functioning L305dt and the same curl cylinder extension happens on the L345.

I can understand how this happens when piston seals are blown due to differential area between the piston side and rod side, but with the spool valve in the neutral position, there should be NO pressure to either side of the cylinder.

All (3) valve banks are setup for (6) hoses - supply/return to tractor, and supply/return to both lift and curl cylinders. This is the way my L305 is setup and operates.

I am also having issues with the lift cylinders, where I can only get 8-10" of stroke out of them, and getting the cylinders to extend requires increasing RPM of the engine. This is odd to me because the curl cylinders appear to have no issue with flow or pressure when actuated. This same issue with the lift cylinders was present for all (3) separate valve banks I have tried. The hydraulic fluid level is also at the full line, so its not a fluid starvation issue.

I have the manual for the 1720 FEL, and have confirmed all hose routing is correct for A, B, C, & D. The hose routing also matches the routing on my L305.

 

[TheOldHokie]

I picked up a tractor that I shouldn't have been looking at in the first place.....fixed all of the electrical issues from the previous owner/hack, and am having trouble with the hydraulics. The 1720 FEL was non-op due to issues with the external pump. I had a spare block to get hydraulics from the tractor, and cannot understand what is happening with the hydraulics. My main tractor is an L305dt, which I've had for a few years now without any trouble. For some reason, I've picked up a couple L345's thinking that I would make myself another nice tractor that I could install my backhoe onto, and its not going how I had hoped....

Anyhow, with this 345 idling, the curl cylinders want to extend with no lever input. The curl cylinders extend and retract as they should when you actuate the spool valve with the lever and the curl extend/function appears to have decent pressure/force, but the self-extension has me scratching my head. To troubleshoot, I have installed (3) separate open center two lever valve banks onto this tractor and all three exhibit the same curl cylinder extension with out lever input. I went as far as taking the hydraulic take off block and valve bank from my functioning L305dt and the same curl cylinder extension happens on the L345.

I can understand how this happens when piston seals are blown due to differential area between the piston side and rod side, but with the spool valve in the neutral position, there should be NO pressure to either side of the cylinder.

All (3) valve banks are setup for (6) hoses - supply/return to tractor, and supply/return to both lift and curl cylinders. This is the way my L305 is setup and operates.

I am also having issues with the lift cylinders, where I can only get 8-10" of stroke out of them, and getting the cylinders to extend requires increasing RPM of the engine. This is odd to me because the curl cylinders appear to have no issue with flow or pressure when actuated. This same issue with the lift cylinders was present for all (3) separate valve banks I have tried. The hydraulic fluid level is also at the full line, so its not a fluid starvation issue.

I have the manual for the 1720 FEL, and have confirmed all hose routing is correct for A, B, C, & D. The hose routing also matches the routing on my L305.

The L1720 came with a 2 spool valve.
Post a picture of your 3 spool valve.

Dan

 

[evantwheeler]

The L1720 came with a 2 spool valve.
Post a picture of your 3 spool valve.

Dan

All (3) valve banks I have tried on this tractor, are 2 spool valve units that I assume came with the L1720 (thats an assumption because they may have been replaced at some point in time). I have (3) L1720 FEL and I have tried all (3) valve banks (all of which are 2 spool with float function on the lift valve) on this tractor, and am having the same issue regardless of the valve bank that is installed. I believe that eliminates the spool valve from being the culprit, because one of the valve banks (as well as the tractor hydraulic take off block) I took right off my perfectly functioning L305 and had the same issue with the curl cylinders extending on the L345. I assumed the spool valve had failed and was allowing pressure to go to the curl cylinders while in the neutral position, but I don't believe that is what is happening after changing out the valve banks.

 

[TheOldHokie]

All (3) valve banks I have tried on this tractor, are 2 spool valve units that I assume came with the L1720 (thats an assumption because they may have been replaced at some point in time). I have (3) L1720 FEL and I have tried all (3) valve banks (all of which are 2 spool with float function on the lift valve) on this tractor, and am having the same issue regardless of the valve bank that is installed. I believe that eliminates the spool valve from being the culprit, because one of the valve banks (as well as the tractor hydraulic take off block) I took right off my perfectly functioning L305 and had the same issue with the curl cylinders extending on the L345. I assumed the spool valve had failed and was allowing pressure to go to the curl cylinders while in the neutral position, but I don't believe that is what is happening after changing out the valve banks.

View attachment 178476 View attachment 178477 View attachment 178478 View attachment 178479

Your loader valve is a two spool valve without power beyond. Are you sure you do not have P and T connected backwards?

Dan

 

[evantwheeler]

Your loader valve is a two spool valve without power beyond. Are you sure you do not have P and T connected backwards?

Dan

Thanks for engaging, Dan.

I have the pressure hose hooked up to "in" and the hose connected to "out" going to the return port on the hydraulic block. Same way my other 345 and my 305 are plumbed, which also agrees with my 1720 FEL Owners Manual. When the tractor is running, the pressure hose it taught, you can tell it is pressurized. I just cant wrap my head around why this thing is behaving this way.

 

[TheOldHokie]

Thanks for engaging, Dan.

I have the pressure hose hooked up to "in" and the hose connected to "out" going to the return port on the hydraulic block. Same way my other 345 and my 305 are plumbed, which also agrees with my 1720 FEL Owners Manual. When the tractor is running, the pressure hose it taught, you can tell it is pressurized. I just cant wrap my head around why this thing is behaving this way.

View attachment 178480 View attachment 178481 View attachment 178482

Thats an open center system. When the tractor is running neither hose should be pressurized. Reverse IN and OUT.

Dan

 

[evantwheeler]

Thats an open center system. When the tractor is running neither hose should be pressurized. Reverse IN and OUT.

Dan

Interesting. I checked my 305 earlier, and while running, the "pressure" hose is also taught, though, I would say not as taught as the 345 is while running.

Thanks for the input I am going to go try it right now and report back.

 

[PoTreeBoy]

Just for grins, make sure your 3ph valve is lowered. Does this machine have draft control?

 

[evantwheeler]

Thats an open center system. When the tractor is running neither hose should be pressurized. Reverse IN and OUT.

Dan

Ok, well, this is interesting. Swapped hoses to the valve on the 345. Front port hydraulic block hose to "out" rear port hydraulic block hose to "in"

Lift cylinders work a charm in this configuration. They work so well in fact, I'm considering going and swapping the hydraulic hoses on my L305 valve to see how it effects that tractor as the lift cylinders are terribly slow. In this configuration on the 345, the lift cylinders load hold fine, there is no cylinder creep, and down function is slow and controlled. Need to go back out and check and see if pressure down lifts the front of the tractor off the ground, I forgot to try that because I got distracted with the curl function......

Unfortunately, the curl cylinders still want to extend with no spool valve lever input. Dump function works, curl back does nothing at all, and the curl cylinders will not retract. I need to go switch the hoses back and get the curl cylinders retracted again because I cant recall now if the curl lever worked properly, I am thinking when I pulled the lever back it dumped the bucket, pushed it forward and nothing happened (but continued to dump because of cylinder creep).

 

[evantwheeler]

Just for grins, make sure your 3ph valve is lowered. Does this machine have draft control?

I was searching the forum earlier and ran across the same suggestion made to other members regarding troubleshooting the 1720 FEL, so I plate with the settings and they didn't have any effect. I believe this tractor does have draft control. Here is the current lever positions and the 3PH is all the way lowered. I believe the inboard lever is draft control.

 

[evantwheeler]

Thats an open center system. When the tractor is running neither hose should be pressurized. Reverse IN and OUT.

Dan

I'm just confused by this. I have (2) tractors both plumbed the same and functioned "fine". Front port of hydraulic block to "in", rear port of hydraulic block to "out" on the 2 spool valves, just like the instruction manual says. This third tractor, no bueno.

Is "in" not the pressure side on the valve body? I know what I just physically experienced with the lift cylinders on this 345 says something is obviously not right with one configuration or the other, but I'm having a hard time understanding how Kubota's instructions are not yielding the expected results.....

 

[evantwheeler]

More data. Went and played with the 345 lift cylinders with this hose configuration. I lifted the arms & bucket all the way up, lift cylinders did great with valve pulled all the way back. I pushed the lever forward and lowered it down and when the bucket hit the ground and a load was introduced to the system, the bucket started raising back up with no change in the lever position......so I'm pushing the valve lever "forward" and the lift cylinders are now extending. I started to pull the valve lever back, and the lift cylinders started to retract and lower the arms until I got the lever all the way back and then the arms stopped and started to lift again....

 

[TheOldHokie]

More data. Went and played with the 345 lift cylinders with this hose configuration. I lifted the arms & bucket all the way up, lift cylinders did great with valve pulled all the way back. I pushed the lever forward and lowered it down and when the bucket hit the ground and a load was introduced to the system, the bucket started raising back up with no change in the lever position......so I'm pushing the valve lever "forward" and the lift cylinders are now extending. I started to pull the valve lever back, and the lift cylinders started to retract and lower the arms until I got the lever all the way back and then the arms stopped and started to lift again....

Its time to stop flailing and do some real organised diagnosis.

1. Disconnect the IN and OUT hoses at the loader valve and put both in a clean bucket.
2. Start the tractor and fluid will come gushing out of ONE of them. Immediately shut the engine off.
3. Vonnect the hose that gushed oil to the IN port on the loader valve and label it as P.
4. Connect the other hose to OUT and label it as PB.

Now test the loader and dont change any more connections!!

Dan

 

[Russell King]

@evantwheeler

See post #1 in this thread that shows a similar hydraulic tap block as what you have on the tractor. It shows how the fluid is diverted using the original cover and the type of cover you currently have installed. (Do NOT think about using just a flat cover or plugging both holes in your existing block. That would damage the pump by a deadheading situation.)

B7100 Hydraulic block diverter (70060-00360 or 70070-00385)

Back in stock. CDN$40 plus actual shipping These are obsolete and no longer available. I have recently been contacted by a member asking if I will make him one of these after reading how I made mine. I know this comes up from time to time and would like to gauge the interest others might have...

www.orangetractortalks.com

Also, I understand that you showed a picture of the three point and draft levers showing draft is down (off?) and the three point lever at the higher up position. BUT you said the arms are at the lowest position. That looks and sounds incorrect to me. But I have never seen a tractor with draft control in person to see how the two levers effect the arms. Nor have I read the operator’s manual that describes their operations. So if you have an operator manual you should try to read that section. And some section on the feedback rod between the lift arms and the three point control valve. I think that might be part of the problem.

The only relief valve in the original system was (probably) in the three point control system. (I know that was how my L185 was set up.). So at the top of the lift (if the feedback rod was not properly adjusted) or in an overloaded situation the relief valve would go into operation. That is normally heard as a squealing noise underneath the seat area. There may be a relief valve in the loader valve but I don’t see any.

The fact that one of the hoses was taut means the pump is in a condition where fluid is being blocked from free flow. That would be a valve actuator divert the fluid to a cylinder or a relief valve being utilized. That is why I think you have some issues with the three point control system (draft, feedback rod, relief valve).

But the tests recommended above should be a great first step in understanding how your system is functioning.