Kubota D1105 Engine - Slow RPM Response to Throttle

[GodHungry777]

Does anyone have any thoughts on why this D1105 takes so long to respond to throttle movement? Where should I start looking?
See start and end of this video (start 0:53 - end 1:46)
The rail on the injector pump moves freely, as does the governor fork.

 

[GreensvilleJay]

hmm, sounded fine starting up and running at 3000 RPM.

Since it 'bogged down' under load, I suspect 'dirty hydraulics'. Perhaps plugged hydraulic filter, sticky relief valve, dirty hydraulic oil ??? Something in the hydraulics NOT the engine.
When were the oil and filters changed ?

 

[GodHungry777]

hmm, sounded fine starting up and running at 3000 RPM.

Since it 'bogged down' under load, I suspect 'dirty hydraulics'. Perhaps plugged hydraulic filter, sticky relief valve, dirty hydraulic oil ??? Something in the hydraulics NOT the engine.
When were the oil and filters changed ?

OK I'll head in the direction of the hydraulics for the bogging issue but what about the slow response to throttle movement?

 

[GreensvilleJay]

The hydraulic pump can't pump oil for some reason(a blockage ?...), puts a heavy 'load' on the crankshaft,slows engine down,guv can't respond fast enough. The only 'load' the engine has is the pump, assuming hydraulics run everything.
I see it every cold day I run the forklift and tilt the mast. It'll raise fine, ONLY tilt causes engine to slow down,it'll actually kill the engine. Odd thing is once oil is HOT, problem goes away....

 

[GodHungry777]

The hydraulic pump can't pump oil for some reason(a blockage ?...), puts a heavy 'load' on the crankshaft,slows engine down,guv can't respond fast enough. The only 'load' the engine has is the pump, assuming hydraulics run everything.
I see it every cold day I run the forklift and tilt the mast. It'll raise fine, ONLY tilt causes engine to slow down,it'll actually kill the engine. Odd thing is once oil is HOT, problem goes away....

I drained the hydraulic tank and removed the filters. Both were dirty. The return filter had actually pulled apart from the pressure of not being able to travel through the filter.
Filters have been ordered. I'll update when i have them in.
There was some gunk at the bottom of the tank and the oil does go creamy when the pump is running. I'm guessing this means there's some water in the system. It goes translucent again once it has settled for a while.
What's the best way to flush the whole hydraulic system so I can give it a good fresh start?

 

[hagrid]

There was some gunk at the bottom of the tank and the oil does go creamy when the pump is running.

You have (had) a restriction on the suction side of the pump. Aeration.

 

[GreensvilleJay]

'best' way ? to clean the rest of it...
Buy an extra 5 Gallon( ?) bucket of oil,
toss it it with new filters,
run for say 10-15 minutes,
full cycle every lever 4-5 times,
idle down,
shut off,
drain/remove all the oil,
inspect/clean the new filters ( or just replace ),
wipe out any remaining oil on the bottom of the tank,
install filters,
add oil,
and you should be back in business.

 

[xrocketengineer]

You have (had) a restriction on the suction side of the pump. Aeration.

Just to keep it clear in my head, would aeration be when air gets sucked in and mixed with the fluid? In this case it seems that the fluid pressure got so low, due to the suction, that it boiled and formed the bubbles (creamy) and when the fluid returns to ambient pressure, it becomes clear again. Unless I am missing something.

 

[North Idaho Wolfman]

I would vacuum out the sludge in the tank!
Your not doing any favors leaving it in there.
Other option would be to first rinse the tank out with Diesel, followed by Denatured alcohol and completely drain and dry the tank.

(NOTE: this is only applicable to Mini EX and EX's and not tractors)

 

[hagrid]

Just to keep it clear in my head, would aeration be when air gets sucked in and mixed with the fluid? In this case it seems that the fluid pressure got so low, due to the suction, that it boiled and formed the bubbles (creamy) and when the fluid returns to ambient pressure, it becomes clear again. Unless I am missing something.

I wager it was sucking some air past a suction line joint. I don't think your pump can apply enough vacuum to vaporize the fluid.

 

[GodHungry777]

I wager it was sucking some air past a suction line joint. I don't think your pump can apply enough vacuum to vaporize the fluid.

Yeah that's what I'm thinking.
New filters should arrive in the next couple of days.
Keen as to see if this fixes the bogging issue. Sure feels like it will.
In the mean time I've striped the light grey sections down and resprayed them. They were covered in surface rust before.