3406E Smoke at idle

[crizz]

Hi guys,

I posted this on Boatdiesel, but thought Id run it past this board as well.

I have a pair of 800hp 3406E in a 2001 560 Sedan Bridge. The boat is new to me as of a couple months ago, and we took our first big trip this week to Key West and back. I noticed as I was pulling into my slip after the return run a fair amount of smoke from both motors, but slightly more from the starboard. There was also some light soot staining on the swim platform and transom, also seeming worse on the starboard side.

It was about a 7 hour run, and I took it easy running at about 60% load.

I was getting toward the bottom of the tanks with less than 1/4 remaining when I arrived. I always use BioBor MD fuel additive, and a proper maintenance dosage was in the fuel being burned.

Wondering about fuel quality, and if potentially the Racors fouled after the long run on low-ish tanks. I am considering a fuel polish and change of all filters.

Am I on the right track, or would any of you recommend a different course of action?

Thank you for any advice in advance, and happy New Year!

 

[Bill Watson]

Maybe not your solution, but worth a try. In a recent cruise, I noticed steam just as you describe -- though my engines are gas. Going into the engine compartment later, and starting the stbd engine showed the water pump leaking. Worth a check methinks.

 

[fwebster]

What color is the smoke you noticed? Black? blue? white?

Fuel systems on Sea Ray boats are usually very good so if you foul a fuel filter what usually happens id the filter just impedes fuel flow and the engine affected begins to stall from fuel starvation.

If you noticed more than the normal amount of sooting, the usual cause is an input air restriction caused by a dirty air filter or a clogged or fouled instake air passage on the aftercooler.

Eliminate the easy cheap stuff first…….1.check the intake air filters
2. change the Racor filters
3. change the Cat Primary fuel filters.

 

[Strecker25]

As Frank said, Smoke color will likely be the most critical piece of information in troubleshooting remotely.

since it’s new to you there’s a possibility this is not a new problem and if it’s black smoke with the sooting id also vote for air restriction or overloading.

Was she surveyed pre-purchase by CAT and did they turn anything up? You’d want to look at their report to see if it was up to WOT RPM properly as a starting point

 

[crizz]

Thanks guys. I hadnt thought about the air filter, but will add that to the list.

The smoke is certainly not white or blue, or the thick black that Ive seen come from old Detroits in working boats. Id call it grayish.

 

[ttmott]

A couple of things to consider -
How many hours on the engines?
Did the boat have an engine survey when you purchased?
Did the engines pull full RPM during the sea trials?
Are they smoking at idle settings?

The 3406e is a robust engine and one of Cat's first electronic fuel control engine. The biggest issue with the 3406 was oil leaks due to substandard gaskets used. The C15 replaced the 3406 with improvements then the C15 ACERT.

To add to what Mr. Webster stated -
Black smoke and excessive sooting on the boat is due to rich fuel condition, which is typically indicative of restricted air intake, excessive turbine blade clearance, poor fuel quality, low compression, or malfunctioning injectors. As both engines are showing the same condition, I would surmise that the injectors are OK and compression is OK.
The first thing to do as Frank says is to clean the air filters.
If there is a lot of hours on the engines then check the blade to housing clearance on the turbine side of the turbocharger - it should be no more than 0.010 inches at any blade. The more clearance the less boost the compressor can make and consequently the richer the fuel to air mixture will be. However, this is an electronic engine so the fuel should be metered to some extent based upon manifold pressure which is the turbocharger's function to build that pressure. Still that clearance should be verified.
Fuel in the US is rarely an issue so unless you have a bad water issue indicated by black algae in the racor fuel filters I wouldn't be too concerned.
One other thing to consider is if there is significant exhaust leakage in the engine room then the air charge into the engine will be contaminated and incorrectly burn causing black smoke and sooting also.

I would also pull oil samples for analysis and look for the soot level but more importantly for fuel in the oil.

 

[crizz]

Thanks for the comprehensive reply.

The engines have about 1750 hours. I had a full hull and separate engine survey done prior to purchase with only minor issues noted. I did oil analysis at both the pre-purchase and just prior to a full service that was just completed by a certified CAT repair service. Im not completely sure if they cleaned the air filter elements, as they have always looked darker in color than other cone filter elements Ive used in the past which were either bright red or bright blue when clean, and darkened over time with usage. Ill have to find out if they did service the air cleaners.

I believe the props need to be checked, as the port engine turns full RPM at WOT when the boat is fully loaded, but the starboard is about 40rpm short. I also notice about a 2GPH fuel burn and 5% indicated load difference between the two motors when RPMs are synced at cruise, with the starboard motor being at the lower load and fuel burn.

 

[crizz]

Also, the oil analysis did not show any excessive soot (or any other issues) on either motor.