D722-E black smoke, won't start

[boatbuilder]

Hi,
First time poster here, located in Ireland.
I bought an old 1 ½ tonne Kubota digger last summer, its model KH-31, with a 3 cylinder D722-E fitted.

I used it all summer and it started straight away if you gave it 20 seconds of preheat. It has been parked up for a few months now and won't start.
I'm just getting black smoke from all 3 cylinders when cranking.

Things I've tried...
- New glowplugs
- New clean diesel
- Check air intake for mice/ blockage
- Take apart and clean injectors (broke one in the process, so I fitted a new one)
-Take apart and clean injection pump
-Bleed air out of pipes

Still getting black smoke when cranking but it's not firing up.

Any ideas on where to go from here?

 

[GreensvilleJay]

hmmm....have you confirmed the glowplugs DO get HOT ???
Quik cheat is to put voltmeter on the strap between the glowplugs. Turn key to 'heat' and read the meter. It should be 11 volts +-. Good battery will be 13-14 volts, no load.
I don't know how the KH-31 powers the plugs, could be a relay, maybe fuse ??
If you have an IR heat gun, point laser at glowplugs see if they're hotter than the block.

 

[boatbuilder]

I'm pretty sure the glowplugs are getting hot, I can feel the whole rocker cover getting a bit warm after a few cranking sessions.
Also I'm guessing that the black smoke indicates that the diesel is hitting the hot plugs?
I even used a jumper cable direct to the glowplugs from a separate battery.

 

[boatbuilder]

The digger has been sitting outside for a few months and we have had a record amount of rain!

 

[85Hokie]

I like the simple idea Jay mentioned :

If you have an IR heat gun, point laser at glow plugs see if they're hotter than the block.

I have done this -I was amazed at how fast that spot gets hot, I am talking about the area AT the plug!

 

[North Idaho Wolfman]

Black smoke is over fuel, or bad fuel.
Are you 100% no gasoline / petrol has been mixed in it?

If the fuel is clean then your more likely to have an issue with the injection pump or the injectors, or both.
I never recommend DYI injection pump or injector rebuilds, they never go well.

DO NOT keep trying to start it, if it does fire off, it's going to run away with itself!

How do you know your getting black from every cylinder?
Did you pull the exhaust manifold and see if puffing black smoke out of each one?

 

[whitetiger]

Make sure all of the hydraulic control levers are in neutral. If one is sticking in the raise or lower position it will crank and smoke exactly as you have described.
They will not start with one of the hydraulic pumps loaded. They just crank and smoke like a freight train.

 

[boatbuilder]

Black smoke is over fuel, or bad fuel.
Are you 100% no gasoline / petrol has been mixed in it?

If the fuel is clean then your more likely to have an issue with the injection pump or the injectors, or both.
I never recommend DYI injection pump or injector rebuilds, they never go well.

DO NOT keep trying to start it, if it does fire off, it's going to run away with itself!

How do you know your getting black from every cylinder?
Did you pull the exhaust manifold and see if puffing black smoke out of each one?

I bought brand new diesel and connected a new fuel hose so its sucking out of the drum.

Yes I took the exhaust manifold off and I can see black smoke puffing out of all 3 ports.

The pump and injectors were a bit fiddly to reassemble but I'm pretty sure it went OK apart from one injector that I managed to break by not aligning the parts properly inside before putting the two halves together. Broke the little pin off inside, so I bought a new injector.

 

[boatbuilder]

Make sure all of the hydraulic control levers are in neutral. If one is sticking in the raise or lower position it will crank and smoke exactly as you have described.
They will not start with one of the hydraulic pumps loaded. They just crank and smoke like a freight train.

I'll have to double check this, thanks!

 

[boatbuilder]

I checked the lever positions and they're all in neutral. Still just black smoke, no start.
I've bought a compression tester with m8 adapter. Any tips on how to do the compression test?

 

[North Idaho Wolfman]

I checked the lever positions and they're all in neutral. Still just black smoke, no start.
I've bought a compression tester with m8 adapter. Any tips on how to do the compression test?

Pull all the injectors or glow plugs depending on which your going to test from.
Grab the fan you should be able to turn the motor very easy, if you can't you have another issue.

Install compression gauge and spin the engine.
Don't add oil or anything else to the cylinders.

You don't have low compression, you have over fuel.
You don't get Black smoke from a low compression engine.
More than likely have bad injectors.

 

[boatbuilder]

Thanks, no harm doing a compression test anyway I suppose.
Would I have to cut this adapter shorter or would it be OK? (At the white mark that I've made in the photo)
Is there a danger that the long adapter could hit the piston?

 

[GreensvilleJay]

hmmm. this..
Take apart and clean injection pump


any chance injector pump isn't 'timed' properly ?

I don't know how it works but considering engine used to run, has hot glow plugs, clean fuel, compression what else could stop it from coming to life ??

believe comp test is a waste of time...as it used to run....

 

[boatbuilder]

I went ahead and did a compression test anyway, seeing as I had bought the test kit. I made the adapter shorter, as per photos of other kubota specific glowplug adapters from a Google search.

Cylinder 1 (closest to fan) - 350 psi
Cylinder 2 (middle) - 364 psi
Cylinder 3 (closest to flywheel) - 388 psi

What do you think of those readings with a stone-cold engine?
From a different thread, I see that someone said that the manual states that compression should be between 337-448 psi, so it seems to be within the acceptable range, especially for a cold engine.

 

[boatbuilder]

Like you've suggested, it may well turn out to be the injectors, but to be fair they looked pretty good.

Would contaminated oil make any difference? Maybe with water from torrential rain or diesel from flooding it?

As it was running previously, I'm not sure how the timing could have changed? I thought the timing was pretty much fixed by the cam lobes underneath the injection pump?

I suppose it's possible that I reassembled the pump incorrectly, but I was quite careful to align things as per a YouTube video. Apparently its possible to assemble the internals 180 degrees out but I took care not to.

The injectors themselves looked pretty good and I cleaned them carefully and replaced one of them with a brand new one that I didn't mess with at all.

 

[North Idaho Wolfman]

Your glow plug adapter was more than likely leaking as it's not the right adapter.
It does not have the seat to seal the plug.
So your numbers are fine, and probably higher than your test results.

Yes you can change the pump output by not timing the delivery valves properly.
Injectors can look fabulous and still be bad, it's all internal parts that are the problem.

You going to keep chasing your tail and shooting yourself in the foot if you don't get the injection pump and injectors tested and properly rebuilt if needed!
Have all the injectors tested as the new one is probably bad too!

Oregon Fuel Injection will do both.
Or since your in Ireland, find a local injection pump service.
If you can't find a good place PM me for other options.

 

[boatbuilder]

Your glow plug adapter was more than likely leaking as it's not the right adapter.
It does not have the seat to seal the plug.
So your numbers are fine, and probably higher than your test results.

Yes you can change the pump output by not timing the delivery valves properly.
Injectors can look fabulous and still be bad, it's all internal parts that are the problem.

You going to keep chasing your tail and shooting yourself in the foot if you don't get the injection pump and injectors tested and properly rebuilt if needed!
Have all the injectors tested as the new one is probably bad too!

Oregon Fuel Injection will do both.
Or since your in Ireland, find a local injection pump service.
If you can't find a good place PM me for other options.

Thanks,
There is a diesel injector service centre in my local town, so it's looking like I'll be paying them a visit! I always like to try fixing things myself if possible because it can get very expensive otherwise!

 

[North Idaho Wolfman]

Thanks,
There is a diesel injector service centre in my local town, so it's looking like I'll be paying them a visit! I always like to try fixing things myself if possible because it can get very expensive otherwise!

Totally agree with you, I do the same.

When you pull the injection pump save all the shims as that is how you set the timing.
And even if they rebuild the pump or you replace it, you will use the same shims as the count never changes unless you surface the block.

 

[boatbuilder]

Good news, I finally got her started!

I drained the oil and filled with fresh 15w40. I also squirted a small amount down each glowplug hole.
I heated the glowplugs for about 30 seconds and she fired up pretty much straight away.

The waste oil smells slightly of diesel.
So I'm not sure if the problem was contaminated oil or low compression.
Compression test figures looked OK so I'm leaning more towards contaminated oil. Thanks to everyone for your advice!

 

[Workerbee]

Theres an excellent way to bend your connecting rods