Boom out is 'jerky' at moderate RPMs - Kioti DK-40 Backhoe

[Coyote machine]

Recent operation of my DK-40 Model 2485 hoe is jerky when booming out to reach things I'm digging. Moderate RPMs, maybe 1800 or so. All other functions are smooth. What to look for/adjust to smooth out the outward motion of the boom/dipper to full reach? Hydraulic reservoir is full, though I could need to change the filters- could that be a factor?
TIA for any help.

CM

 

[RNeumann]

Anything else change? Did you just hook it up? Does it run smoothly at other RPMs? Did you just try to lift or move something or run into something? Etc
Could be something simple like an improperly seated QD or some air in the circuit. But understanding what was happening before the problem started would help.

 

[Diggin It]

Everything fully lubed and free of gunk? Possibility of something binding?

Any unusual noises?

 

[Coyote machine]

Anything else change? Did you just hook it up? Does it run smoothly at other RPMs? Did you just try to lift or move something or run into something? Etc
Could be something simple like an improperly seated QD or some air in the circuit. But understanding what was happening before the problem started would help.

No, yes, for the most part, No. It's behaved this way for a long time, I guess, just more pronounced at higher RPMs. It makes it hard to operate because as the boom and dipper reach out it bounces the hoe and tractor due to the weight and speed. Last 'change' to the hoe was adding a couple of feet to one of the hoses connected to the rear remote and return/fill QDs. The hoe had been off for a long time, mostly undercover. It's been on the tractor for a few months, with intermittent use.

 

[Coyote machine]

Everything fully lubed and free of gunk? Possibility of something binding?

Any unusual noises?

All zerks greased before install. Don't believe any 'gunk' is present; have been digging in some muddy conditions though. No noises really, just usual operation with the jerky boom outwith dipper out at same time. Could it be one circuit competing for flow? Meaning if both sticks are being operated at the same time the boom out might want the flow the dipper out is taking away from the boom circuit or similar?

 

[rScotty]

Recent operation of my DK-40 Model 2485 hoe is jerky when booming out to reach things I'm digging. Moderate RPMs, maybe 1800 or so. All other functions are smooth. What to look for/adjust to smooth out the outward motion of the boom/dipper to full reach? Hydraulic reservoir is full, though I could need to change the filters- could that be a factor?
TIA for any help.

CM

When my hoe began to do that it turned out to be old seals in the dipper cylinder. It eventually got to the point where in certain positions the cylinder would make a squawking sound as that cylinder extended. I took the cylinder off and had it rebuilt. It was a simple seal replacement job and total cost was a couple hundred bucks at the hydraulic shop. Problem fixed.
rScotty

 

[RNeumann]

When my hoe began to do that it turned out to be old seals in the dipper cylinder. It eventually got to the point where in certain positions the cylinder would make a squawking sound as that cylinder extended. I took the cylinder off and had it rebuilt. It was a simple seal replacement job and total cost was a couple hundred bucks at the hydraulic shop. Problem fixed.
rScotty

Based on the OPs follow-up (ongoing issue that didn’t start after a specific event but has gotten to the point of frustration) I’m thinking the same thing- time to tackle the cylinder.

 

[rScotty]

When my hoe began to do that it turned out to be old seals in the dipper cylinder. It eventually got to the point where in certain positions the cylinder would make a squawking sound as that cylinder extended. I took the cylinder off and had it rebuilt. It was a simple seal replacement job and total cost was a couple hundred bucks at the hydraulic shop. Problem fixed.
rScotty

Some more info. The cylinder on mine wasn't leaking and other than the jerk and squawk it had full power. The hydraulic shop said that the internal seals in the cylinder piston were loaded and caked with a real fine dust-like material like a mixture of fine clay and chalk and oil. Not abrasive, in fact it had polished the cylinder bore to a mirror finish. So all it needed was cleaning and fresh seals.

I also changed the filters and went from using JD Hygard hydraulic fluid to a high detergent motor oil in the hydraulics - that's what JD recommends for this particular tractor. Then a 2 years later I changed fluid and filters again. Haven't seen the problem again.
rScotty

 

[Coyote machine]

Some more info. The cylinder on mine wasn't leaking and other than the jerk and squawk it had full power. The hydraulic shop said that the internal seals in the cylinder piston were loaded and caked with a real fine dust-like material like a mixture of fine clay and chalk and oil. Not abrasive, in fact it had polished the cylinder bore to a mirror finish. So all it needed was cleaning and fresh seals.

I also changed the filters and went from using JD Hygard hydraulic fluid to a high detergent motor oil in the hydraulics - that's what JD recommends for this particular tractor. Then a 2 years later I changed fluid and filters again. Haven't seen the problem again.
rScotty

Curious what the thinking was on how the cylinder got clay, and chalk and a mixture of other dust, etc. into it? Also why would Deere recommend an engine oil rather than their pricey Hygard hydraulic oil? Also, how many years/hours did your hoe have on it when you rebuilt the boom cylinder?

Currently I'm working on a few other issues with the tractor, but first thing I plan to do is change out the two hydro filters and top off the HST reservoir, then retest the hoe's function. I'm not against rebuilding the boom cylinder; however I don't want to do it before checking that things like an overdue filter change aren't the culprit. So for me, a rule-out of the simple, less expensive fixes is a necessary method of approach. Also, though my hoe is from 2009 vintage, it does not have a ton of hours on it overall. It has spent winters either outside, or under cover outside, and a few years wintering in my heated barn with the tractor attached.

 

[Diggin It]

The hydraulic shop said that the internal seals in the cylinder piston were loaded and caked with a real fine dust-like material like a mixture of fine clay and chalk and oil. Not abrasive, in fact it had polished the cylinder bore to a mirror finish. So all it needed was cleaning and fresh seals.

Why only one cylinder?

If it was in the oil or system, why wouldn't it affect all cylinders and components?