Kubota 05 Series Engine - Bogging Under Load, Loses Power When Warm (Kubota KX41 - D1105 Engine)

[Godhungry777]

Any help diagnosing this would be appreciated.
Purchased KX41 as a project with this condition.
Bogging under load - 3300rpm will drop to 1800rpm when any load is added (See Video at bottom)
This includes crawling, raising and lowering boom, etc.
Seems to get worse as it warms up (drops 300-500rpm when cold but 1300-1500rpm when warm)
Doesn't smoke any colour at any time in the process.

Here's what I've done so far:

• emptied and cleaned fuel tank (had water, rust and gunk)
• replaced fuel filters (clogged with water and gunk from tank)
• replaced fuel lines (lines were brittle) - had injector pump and injectors tested - tested ok
• bled injector lines
• replaced engine oil and oil filter
• replaced thermostat and coolant (thermostat was stuck open)
• air filter had already been replaced - exhaust is clear
• checked governor spring, forks and flyweight. Warn but nothing broken or missing

Let me know if there's anything i can add to help diagnose this.

 

[TMGT]

What are the hrs on it? Have you checked compression and valve lash?

Sent from my SM-G715U1 using TractorByNet mobile app

 

[90cummins]

You are dead heading the hydraulics creating max pressure & bypass because the hydraulic cylinder is at the end of its travel.
Try actually working the machine.

90cummins

 

[Godhungry777]

Thanks TMGT.
I had dismissed this as a probable cause because there's no smoke.
Shouldn't I expect smoke of some sort with compression/valve lash issues?

 

[Godhungry777]

You are dead heading the hydraulics creating max pressure & bypass because the hydraulic cylinder is at the end of its travel.
Try actually working the machine.

90cummins

Thanks 90cummins.
Yeah, it does the same thing just lifting and lowering the boom.

 

[Godhungry777]

What are the hrs on it?

Sent from my SM-G715U1 using TractorByNet mobile app

4000 hours

 

[Fixastuff]

You are dead heading the hydraulics creating max pressure & bypass because the hydraulic cylinder is at the end of its travel.
Try actually working the machine.

90cummins

Thats what I thought when I read his description but listening to the engine on the video it doesn't sound like that to me. Sounds like it just idles down not like it's being lugged down by deadheading.

 

[Godhungry777]

Sounds like it just idles down not like it's being lugged down by deadheading.

What do you think about the way it takes so long to rev up or down after the throttle has been increased or decreased (as seen in the video)?
Could that be pointing at an issue?

 

[Godhungry777]

I was also wondering about an issue around the governor. But you can see the governor fork activate when the engine starts (see video below) to bring revs to the throttle setting.
But it doesn't seem to move when I apply the load in the video.
I did end up pulling the governor shaft (with flyweight) out to check it's action and while it is worn, it does move freely.