Haze from Exhaust

[Yearwood]

Have 300 HP Yanmar 6LP w/Albin 28TE (2001 model) abt 1500 hours and have been noticing a black exhaust haze (not heavy at all but somewhat consistent) at cruising speeds (3400 rpm) and below say to 2500 rpm. Presume it is excess fuel.

Has anyone dealt with this issue???

[RobS]

Overloaded? What is your true WOT?

[Yearwood]

Not overloaded. Have been running at 3400 rpm for 10 years. Not fuel quality either nor fuel filter. Not burning oil. I'm guessing it is either timing, dirty injectors or leaky exhaust vale(s).

Hope to hear from someone who has dealt with the same issue.

Expect to hear shortly from a diesel service company that has been maintaining a number of 6LP's.

[Yearwood]

Diesel mechanic (who has saved us a bundle in the past) says basis age, description, etc. it is either the turbo-charger (new one cost $3000) or injectors (new ones cost $1500). Have cleaned the turbo in the past.

In any event anyone have experiences with this on this engine? Prices reasonable?

[RobS]

I remembered replying to this same issue in the past. I searched old posts and find that you posted the same thing in 2009. I had asked a similar question regarding engine loading and WOT and did not get the answer then either.

Since you seem convinced she is propped right and not overloaded, I will offer another cause of black smoke in the exhaust and that is air restriction.

Not getting enough air can be caused by a dirty/collapsed air cleaner, a leaking turbo hose, a filthy aftercooler or air restriction inside the aftercooler, a worn out or partially stuck turbo, or a poorly ventilated engine room. Any combo of these can restrict air to the engine causing dark smoke and further, low power.

[Yearwood]

Air cleaner is fine, intercooler could be dirty, ventilation is fine/unchanged. Coming down to turbo charger, valves, intercooler or timing.

[jleonard]

I doubt timing has changed, injectors are usually one of the last things to look at in a diesel unless it idles rough or starts hard (and smokey when it's warm out).
A turbocharger is "bad" if the compressor wheel has too much play and hits the housing. You can check that yourself. With the engine off remove air filter and grab the compressor wheel nut. with only a few lbs of force wiggle the nut up and down, side to side. Then pull out and push in. If the wheel hits the housing the bearing is worn and it needs a rebuild.
If you have never cleaned your intercooler and intake system, then you need to do that first. Yanmar sells "blower wash" or "turbo wash" ro something like that. You spray it into your turbo while under load and it cleans the turbo wheels and intake plumbing. Then you rinse with plain water.
I don't know how valves lash out of adjustment will affect a Yanmar.
I know that won't make a Cummins smoke.
My ex marina neighbor had some hazy smoke with his 4 banger Yanmars (190s) and he solved that by simply using a fuel cetane booster as nailed by our local Yanmar dealer. Seems Yanmars are sensitive to fuel quality and they need a shot of drugs now and again to run clean. He always added per the bottle recommendations and never saw smoke again.

There, I'm tapped out for the diesel engine category except for one question:

Do you listen to "Smoke on the Water" or Purple Haze" when you boat?

[Russell]

The time I had trouble with smoke turned out to be barnacle growth on my propeller. I learned that stuff grows rapidly down here in the summer with water temperatures up to 80 degrees. Make sure you can hit your rated rpm at WOT.

[Yearwood]

Russ -- not an issue. Boat is kept on a lift and propeller is squeeky clean.