Black smoke

steviep · Mar 13, 2018

So I just got my 4300 back together again. This time I had the injectors checked and rebuilt. Now it's blowing what I won't call black but very dirty smoke. I have been told that air in the lines will cause this. What's everyone's thoughts.

Kubota 2350 · Mar 13, 2018

Sounds like the injection timing needs to be checked and adjusted.

mike48130 · Mar 13, 2018

How much? Assume it is worse than before? Air in then lines will be gone in short order at high rpm with those short lines.

How many hrs and what work did you do to it? And why?

steviep · Mar 13, 2018

Last year the engine was rebuilt , this year I blew the head gasket. The head did over heat but it didn't get warped , put a new head gasket in and reassembled. While waiting for the head to return the injectors were sent out tested and rebuilt. Engine starts right up just really Smokey.

cruz54982 · Mar 13, 2018

black smoke is usually caused by lack of air or to much fuel = mouse nest in air intake while engine was apart ? or any other obstruction in air .

steviep · Mar 14, 2018

No blockage, I had it all off including the manifold and cleaned it all before putting it back together.
It seems to be like really dirty exhaust not so much like black soot. If the injector timing is off I know the pump only has about 3/8 adjustment and I know how to loosen it to adjust the pump . But do you adjust it by eye in till the smoke clears up.

mike48130 · Mar 14, 2018

If you didn't adjust it I wouldn't until you absolutely have to. There is a timing procedure in the service manual.

I would remove the nut on one injector line at a time, then start it and see if it gets better. Maybe you can identify one cylinder causing the problem.

I would call the shop that did the injectors as well. Did they set the springs correct? I think the manual has the settings for the springs and shims.

larboc · Mar 14, 2018

steviep said:
No blockage, I had it all off including the manifold and cleaned it all before putting it back together.
It seems to be like really dirty exhaust not so much like black soot. If the injector timing is off I know the pump only has about 3/8 adjustment and I know how to loosen it to adjust the pump . But do you adjust it by eye in till the smoke clears up.

Spillover timing is adjusted by making a tube tool out of a wd40 straw and an extra injector line. The right side loader arm has to come off to see the mark, and it's not a very accurate way to do it IMHO because there is no pointer, just trying to center it up in a cast iron hole. Keep in mind the rear most cylinder is cylinder #1 in yanmar world. You should at least check it to see where you are. I'm suspicious of your timing set marks. There is enough adjustment in the IP timing to blow a head gasket, BTDT.

With it idling, you can crack each line at the IP to kill each cylinder and see if it makes a difference. I'd guess one of the injectors didn't get put together correctly and is dribbling. Cracking the nuts will tell you right away if it's a certain injector.

FYI you can get the injectors out pretty easily. Pull the air cleaner and hose, reservoir tank, injector line clamps, injector line nut at the IP of the cylinder you're going to pull, and put a spray paint can cap over the intake to keep extra parts out of the engine. You can fish your way into the injectors and pull them out, even #1, without pulling the tank. Lightly sand the copper washers and reuse them, they will be fine. Make sure your return line is in good shape and clamped onto the injectors.

jd110 · Mar 14, 2018

Extra smoke can also be caused by low compression. Usually smoke from low compression is light gray or white due to incomplete combustion. Loosen one injector at a time and see if smoke clears when one cylinder is loosened. Then pull nozzles and check compression. If compression is good on all cylinders, then send nozzles in for recheck.

DLTTrekkers · Mar 15, 2018

Returnline pinched or blocked ?

steviep · Mar 19, 2018

The newest developments , I replaced the fuel, fuel lines, and fuel filter. Now t the exhaust is a light gray while idling. Darker when revved up but not as bad as before.

larboc · Mar 20, 2018

steviep said:
The newest developments , I replaced the fuel, fuel lines, and fuel filter. Now t the exhaust is a light gray while idling. Darker when revved up but not as bad as before.

Did you crack lines to see if it was from a certain cylinder? Not hard to do at the pump but mind your PPE and have some rags.

mike48130 · Mar 20, 2018

Yeah would do that and check the valve backlash. If the head was off that could causing it as well.

TimberHole · Mar 21, 2018

Probably should have checked compression before pulling the head and had the head checked when it was off. Missed opportunities!

steviep · Mar 21, 2018

I had the engine rebuilt with oversize pistols last spring. I had the head done at that time. I had the head checked this time too they replaced the seals again. And yes I did crack the injection lines and you definitely could here a difference in the engine.

TimberHole · Mar 21, 2018

steviep said:
I had the engine rebuilt with oversize pistols last spring. I had the head done at that time. I had the head checked this time too they replaced the seals again. And yes I did crack the injection lines and you definitely could here a difference in the engine.

My apologies, I should have re-read the entire thread before posting!

larboc · Mar 22, 2018

steviep said:
I had the engine rebuilt with oversize pistols last spring. I had the head done at that time. I had the head checked this time too they replaced the seals again. And yes I did crack the injection lines and you definitely could here a difference in the engine.

Did a certain cylinder make any more or less of a difference than the rest when cracking the line? Did you check spillover timing?

steviep · Mar 24, 2018

After letting it run for a while today the smoke cleared up a lot . On idle it has a light white but revved up it has a lot more white smoke. I don't quite under the injection pump timing .

larboc · Mar 26, 2018

steviep said:
After letting it run for a while today the smoke cleared up a lot . On idle it has a light white but revved up it has a lot more white smoke. I don't quite under the injection pump timing .

Do you have the manual so you can do the spillover timing check procedure?

It almost sounds like you're experiencing the same thing mine did before I cranked up the timing (which got rid of the smoke, but blew the head gasket).

I would check timing, and then if it's within spec, put an hour of medium varying load on it.