D722

[Gdubs]

Just purchased a used d722 that had been in storage since 2020. Guy said he fogged it with oil and sealed it up, which it looked like he had, everything looks good.

I bench tested it last night after giving i fresh oil and filter, with some Lucas diesel treatment in fuel I used, and it started right up amd sounds perfect, but has excess dark smoke from exhaust and black sticky residue of what I can only assume is in burned fuel at the exhaust manifold.

Are there any steps I missed on firing up an engine that had sat so long?Any guess on the excess smoke?

I’ve read about wet stacking and needing engine load to correct that, I just have no way of putting it under load until I get it into my machine.

 

[kubotafreak]

It takes a bit to burn out the oil he fogged it with. Should clear up once warm. If it does not it may have some issues. Hope he actually used fogging spray and not just motor oil. These small kubota engines can get messed up with extra motor oil( poured in), and starting fluid.

 

[Gdubs]

Yeah I think he mentioned he used a 5w motor oil

what kind of issues do you mean?

i didn’t want to run it too long on the bench without a cooling system hooked up, wasn’t sure how long it could go.

 

[kubotafreak]

Specifically for that(motor oil) commonly used by mistake to test ring compression(good for gassers, bad for small diesel). The small super series have such small piston clearance volume the oil hydro locks the cylinders, bends rods, or cracks rings/lands. Black smoke can be an indicator of lower compression in the damaged cylinder.

hopefully yours just is dirty with extra oil. Easy way to clear out the cylinders in that type of situation is by pulling all injectors/glow plugs and spin it over to push out all the extra in the cylinders before being run.

 

[Gdubs]

Ok

I’ve run it a few minutes already. Too late to clear it now? Or pull the plugs and injectors and spinning it still viable?

 

[kubotafreak]

I would button it up with cooling system, so you can go full heat cycle. If it doesn't clear up I would compression check it through the glow plugs.

 

[Gdubs]

I would button it up with cooling system, so you can go full heat cycle. If it doesn't clear up I would compression check it through the glow plugs.

I’ve never set up the fan/radiator in bench test, do I just mount it all up like it would go in the machine?

 

[kubotafreak]

For a 722 it should be the belt driven water pump/fan, and the two hoses for the radiator. I assume you already have a little lift pump for the fuel. You should be good then to run so it can hopefully burn off the oil in the cylinders/exhaust, without overheating the engine.

If you have access to the glow plug adapter (10mm if my memory serves) it wouldn't hurt to just compression test it too.

 

[Russell King]

Did you spin it over by hand before you cranked it up.

Did you open the decompression before spinning it up during starting?

Either would probably clear excess oil.

I would doubt that it would spin if there was too much oil in any cylinder. A starter motor might have enough power to do some harm but that seems like it would just stop.

Hopefully more experienced people can comment on the probability of damage

 

[lugbolt]

Did you spin it over by hand before you cranked it up.

Did you open the decompression before spinning it up during starting?

Either would probably clear excess oil.

I would doubt that it would spin if there was too much oil in any cylinder. A starter motor might have enough power to do some harm but that seems like it would just stop.

Hopefully more experienced people can comment on the probability of damage

depends on the version of the D722. Some had a direct drive starter, others a PMGR (permanent magnet gear reduction) starter. The former, it will crank the engine but a cylinder full of oil it will struggle. The PMGR starter, sometimes they don't even know there's oil in there....or debris...or whatever. They'll just crank 'em over and bend/break parts and not think twice.

Not all D722's had a compression release.

was the engine a little hard to spin over the first time you tried? Sorta like an old truck with the timing too far advanced? Crank, stop, then crank normally? If so, could be bent rod(s). If not, hook up your cooling system, get it running and go full throttle and leave it that way. The engine should develop enough heat in the manifold to burn any oil out. If it doesn't, shut it down, let it cool off, then remove the exhaust manifold. Then start the engine. Which cylinder isn't running? It'll be obvious.

 

[Gdubs]

Did you spin it over by hand before you cranked it up.

Did you open the decompression before spinning it up during starting?

Either would probably clear excess oil.

I would doubt that it would spin if there was too much oil in any cylinder. A starter motor might have enough power to do some harm but that seems like it would just stop.

Hopefully more experienced people can comment on the probability of damage

Yes I spun it over as much as I could by hand before hooking a battery to it.

when I hooked power to it it spun easily and started right up, just smokey

didn’t even realize the possibility opening decompression first

 

[Gdubs]

depends on the version of the D722. Some had a direct drive starter, others a PMGR (permanent magnet gear reduction) starter. The former, it will crank the engine but a cylinder full of oil it will struggle. The PMGR starter, sometimes they don't even know there's oil in there....or debris...or whatever. They'll just crank 'em over and bend/break parts and not think twice.

Not all D722's had a compression release.

was the engine a little hard to spin over the first time you tried? Sorta like an old truck with the timing too far advanced? Crank, stop, then crank normally? If so, could be bent rod(s). If not, hook up your cooling system, get it running and go full throttle and leave it that way. The engine should develop enough heat in the manifold to burn any oil out. If it doesn't, shut it down, let it cool off, then remove the exhaust manifold. Then start the engine. Which cylinder isn't running? It'll be obvious.

will do that

i would attach a video of it running but I guess you can post only pics here?

 

[Gdubs]

It dawned on me this morning to recheck the fuel return lines, I indeed had them routing right into each other hence to return to tank. Changed that and it fired up, but still Smokey

I cracked each injector and #3 started spraying fuel straight up (not the typical dribble from the top of nut) and no change in idle, but the smoke stopped. When I re tightened it, the smoke started again.

I switched that injector out with what I presumed to be a good injector from my d902, (same kubota part number) same spray, same smoke.

could it be two bad injectors? Or cylinder issues causing injector to spray back at me when cracked?

 

[Russell King]

No expert on the injector and spray vs dribble when cracking the line... but I will relay this information

I have an old L185 and replaced the injectors and bled the system. The lines were at dribble levels when bled. The lines were a bit wonky so I bought new lines and replaced the lines between the pump and injectors. When bleeding them seemed to be more fuel out.

Both times after tractor started. I cracked one injector at a time. Old lines would sort of flow out but not shoot out or up. Second time there was a definite stream of fuel that shot up between the nut and line vertically

The old lines had significant paint on them and the new ones are not painted at all so the new lines probably have a clean path while the old ones are gummed with paint and old residue

In short it is probably a good thing

 

[kubotafreak]

You can have black fuel smoke from incomplete burn. Either through low compression, or over fueling. Doubtful you have an injector issue…

 

[Gdubs]

You can have black fuel smoke from incomplete burn. Either through low compression, or over fueling. Doubtful you have an injector issue…

Would the low compression or overfueling cause any difference in how the fuel came out of the injectors when cracked?( #1 and #2 run out, #3 shoots straight out)

 

[Gdubs]

Found problem

#3 port of injector pump is not firing properly. Other two are squiring fuel in sequence but it skips the 3rd and it just flows out

Any fix for that other than sending it to a shop for calibration?

 

[Gdubs]

Found problem

#3 port of injector pump is not firing properly. Other two are squiring fuel in sequence but it skips the 3rd and it just flows out

Any fix for that other than sending it to a shop for calibration?

Pulled injector pump and this is what inside of gear case looks like
Is this engine toast due the rust?

 

[kubotafreak]

Is the pump follower/lifter seized? If you can free that portion up you might be ok. Once they get corrosion in the fluted fuel plunger its prob toast.

 

[Gdubs]

No, I disassembled the the pump it’s all fine, just carbon deposits on some of the parts, but the plunger, spring etc are all good

that rust on the inside of the case worries me though