Diesel Smoke

[jrirvine1]

Late this season I noticed some light gray smoking from both engines that would not dissipate until after running for several minutes at our typical cruising speed at 2200 rpms. When returning to the dock, most smoke had dispelled but would occur again at start up and be noticeable when remaining in the slip at lower rpms. I have not noticed any drop in performance and the engines appear to be running at specifications.

Due to this occurring with both engines, although more with the starboard, my suspicion is that this is a fuel and or dirty injector issue. Two other boats that purchased diesel at the same location did need to have all fuel removed and treated around the same time I noticed the additional smoke, so it is quite possible that we had full tanks of questionable fuel. Unfortunately, if we are unlucky enough to purchase some dirty fuel we end up with a lot of it and in my case about 300 gallons, which should be more than sufficient to clog injectors or cause other problems. Before winterizing, I ran out most of the suspect fuel, then fueled up at another location and added fuel treatment that included both stabilizer and injector cleaner.

My question at this time is what would our experienced diesel dudes recommend that I do at spring commissioning time? In addition to changing the racors and running the boat with the injector cleaner mix in the fuel, are there other things that should be done and thoroughly checked?

 

[fwebster]

1. If you are running 30 micron or smaller Racors, your Racors will stop fuel flow before the dirty fuel affects either engine. Your engine mounted filters are probably 2 micron so the chances of dirty fuel causing smoke is slim to very unlikely.

2. The fact that both engines are affected also makes dirty fuel an unlikely cause. Even if you bought a load of sludge with your last fill up, the chances of both engines being affected at the same time isn't likely.

3. A dirty injector will not atomize fuel properly. A poor spray pattern causes droplets not spray to be injected. Droplets will caluse imcomplete combustion and incomplete combustion causes blue smoke, not gray.

4. Having a dirty injector due to bad fuel is possible but dirty injectors in both engines at the same time isn't very likely.

5. Gray smoke........? Are you sure you are not seeing condensation in the exhaust. As temperatures cooled late in the season boats that shoe no smoke earlier, will show some exhaust condensation.

6. If you think you got a load of bad fuel, by all means treat the tanks with a biocide and Power Service Diesel 9-1-1 as soon as you can next year. The 9-1-1 is designed to break up clumps of sludge so that the fuel can be processed by normal onboard filtration means. You may need to change Racors after the first tank goes thru, but it is a lot easier and cheaper than having your fuel tanks cleaned.

 

[jrirvine1]

Thanks Frank.
I first noticed the smoke in the starboard engine and then somewhat later in the port side. My assumption was this was due to the large amount of fuel that may have become contaminated and just took longer to affect the port side. When fuel treatment trucks begin pumping out boats adjacent to you that purchased fuel at the same location during the same time, this does raise or give cause for some concern.

The temperatures were still warm when I saw the smoke in probably mid September. I have had some others have a look at the engines when idling and the consensus is that this should clear up with the treatment. But I thought this also might be a question to pose to this group. If nothing else, we have learned where not to fuel up next season.

 

[jitts3]

Is your engine mechanacal or electronic. (ECM od injector pump) Not very famalliar with modern marine deisels. However I own a Peterbilt truck and have good background in diesels and fuel.
There are many blends of deisel around now. at least on highway fuel. We have been running low sulpher for a long time now. Now we have Ultre Low Sulpher as well as Bio Diesel. An older mechanical truck that a friend of mine has will blow some grey smoke at idle. One is a 62 Series detroit and the other a 400 Big Cam Cummins. This is typical of these trucks. You may have changed to a different fuel and not realized it.
My Peterbilt (C16 CAT) will burn anything but I have been having fuel filter issues since the ULSD changover and some of my friends are now having Gelling trouble at lower temps that have not had trouble before.
Again, not a marine diesel guy, but check out the different type of diesel available to you and perhaps try to stick with the old reliable LSD (Low Sulpher Diesel) and try to stay away from Bio. The EPA has saddled us in the trucking buisness with this. I bet it blead over to marine use as well.
If the boat runs as it always has, then I would look and the fuel type. Try different ones if possible and see if it goes away.

 

[jrirvine1]

Jitts, my understanding of the 480CE series Cummins is that this nomenclature means “C” series with mostly, but not all Electronic functions. The fuel system has an electronically governed inline fuel pump at high pressure. To get to a totally electronic engine with common rail fuel delivery system you need the next generation which is the QSB and QSC series.
The light gray smoke that I saw is probably nothing to be overly concerned about, but when something changes, you always want to know why. I am now thinking that this could be something as simple as dirty air filters, as mine constantly got semi covered last season with golden retriever fur that somehow found its way into the engine room. Guess I shouldn’t have trained the dog to hand me tools. Perhaps a fine cleaning of the filters is all that is needed.

 

[jitts3]

I agree, when something changes, you want to know why. Could very well be a clogged air filter. I've found out that also kills an engines efficiency more than most think. Has it seemed to be thirstier than normal?