Engine smoking

[Hooligan]

 I am having a problem with my universal 5444 smoking.  It is fine when running out of gear but when under load i have smoke out of the exhaust. Gray smoke not white nor black. No over heating. Oil and
coolant topped off. Other then that engine starts and runs fine. Any ideas?

[S/V Deo Volente]

Did this start suddenly? Generally that indicates an increased load or a restricted intake.
Bob

[Hooligan]

  I just got the boat. Don't know when it started. What do you mean by increased load? It is under normal load. Clean bottom. Clean fuel. Restricted intake? Air, fuel or water?

[S/V Deo Volente]

The engine is "under load" when in gear, In a boat it is properly matched when you can achieve hull speed when getting to 90-100% of the maximum rpm's. "Increased load" is when something changes making the engine work harder, generally not getting to 90% of maximum rpm. A sticking shaft brake or having too much pitch on a prop will overload the engine. A restricted air intake will cause an imbalance in the air/fuel ratio, too much fuel = gray to black smoke.
If you think the smoke is more of a bluish tone it will be oil.
Bob

[Hooligan]

I do not think it is under any extra load the boat performs well. The smoke is more gray then blue. It may be a fuel problem. Bad injectors? Pump?

[S/V Deo Volente]

Injectors can certainly be a problem, and should be serviced periodically. It wouldn't hurt to pull them and have them tested. The pump is less likely. I would start with the injectors if you can run wide open near max rpm and the intake is clear.

[P69]

My engine (also a 5444) labored a lot when the prop was covered with barnacles, couldn't get it over about 2200  at full throttle and over heating.

Don't recall color of any smoke out of exhaust, there was too much steam.

I'm sure you checked the prop, so this is probably not the issue and, since not overheating, I don't think this is the issue.

I know that while trouble-shooting my generator (1 cyl diesel) a while ago, it was outputting white/gray smoke from atomized fuel. The gen was  cranking, but not firing.   Maybe, as someone else mentioned, you've got unburned fuel.

Regarding injectors, here is the kubota part number for replacements (about $60 each): 
  original part number: 15271-53020
  Replacement part number: 70000-65209

Often the original part number was xxxxx-xxxxx, then kubota replaced that part number with yyyyy-yyyyy, but the part is the same.

If they ask which tractor the engine is in, tell them R400 loader.

Here is online parts diag for kubota
http://kubota.com/part/partsList.aspx#

Enter R400 in Model Name search field, then open the result.

Good luck

[Hooligan]

P69 Thanks for the Kubota info,  I am hoping it is just an injector proplem and not the pump

[PeteW]

I've seen this problem with black smoke under load before on
a Yanmar. It turned out to be a restricted exhaust manifold
and mixer. Carbon build up.   Pete

[Hooligan]

Pete it has a new ehaust mixer. So I don't think it is that.

[Hooligan]

I went to a real machanic and he said the smoke was not unusual for an engine this old. I am going to
pull the injectors and have them inspected. The engine is running fine with 2700 hours on it.

[kevin barber]

Are you positive that it is not steam?   How much water do you get out of the exhaust?

5444's are known to run hot.  Mine steamed for years before I changed out the raw water pump to the newer Oberdorfer with increased output.

[Hooligan]

No not steam. Smoke is not white but very grey Engine is not overheating. I jost put on a New Oberdorfer pump

[Hooligan]

 P69 thanks for the tip on the Injectors. I ordered 4 for $63 each. I think Unversal gets almost $200 each.