ZD321 with D782 Diesel engine

[Jdw3319NC]

Purchased a zero turn ZD321 with D782 engine. Engine has knocking sound. Afraid to run it as I don’t want to cause more damage. I unsuccessful in posting a video with sound but will try to add somehow. Hoping someone with experience may be able to steer me toward steps to take to diagnose and repair. Thanks

 

[lugbolt]

Nice picture. But no video?

if it's knocking do a compression test. That will tell you the condition of the cylinders. If low (under 400 psi) you will want to pull the head and inspect the cylinders and piston tops. You may find poor cylinder wall finish, maybe some metal transfer-look particularly at the center cylinder. If you do find that, you'll probably want to pull the engine and go through it.

 

[kubotafreak]

Drain a little oil out, see if there is any metallic flakes.

 

[GeoHorn]

When I hear someone complain about “knocking”.... I think about mechanical failure of main or conn-rod bearings or piston-slap due to mechanical failure. (Diesels have a ”light knocking” sound which is quite ordinary because of the compression-ignition system. A true “knock” would be caused by mechanical failure.)

A stethoscope might isolate the location of the ”knock”. If it is coming from all cylinders you might consider having a professional diesel engine technician advise you further.

Otherwise, I’d drain the oil for spectroanalysis and cut the filter open to look for metal, and while the drain plug is out, use a boroscope to observe the condition of main journals and connecting-rods at the cranshaft while the engine is slowly rotated forward and backward looking for contrary movement of the conn rods at their bearings with the crank. Look also for camshaft looseneess (might require removal of a gearcase cover.)

A Kubota dealer with an experienced diesel technician can be your friend here.

 

[Jdw3319NC]

Nice picture. But no video?

if it's knocking do a compression test. That will tell you the condition of the cylinders. If low (under 400 psi) you will want to pull the head and inspect the cylinders and piston tops. You may find poor cylinder wall finish, maybe some metal transfer-look particularly at the center cylinder. If you do find that, you'll probably want to pull the engine and go through it.

I added video. I was having a problem figuring out how to do it. Thanks for your input

 

[kubotafreak]

Any chance you got a sample of oil? That will put all speculation to rest if you have phantom knock or some other engine issue.

 

[Jdw3319NC]

Any chance you got a sample of oil? That will put all speculation to rest if you have phantom knock or some other engine issue.

I have not drained the oil but it looks clean on dip stick. I plan to drain and check fir metal. Thanks

 

[GeoHorn]

I have not drained the oil but it looks clean on dip stick. I plan to drain and check fir metal. Thanks

IF it looks clean... it’s either fresh oil or cheap oil. Good oil in even a healthy diesel will get black pretty quickly. OIl that is run for very long and still clean has lousy detergent/additive-package.