Diesel Exhaust

[bbistis]

Anyone solved the issue of black soot stains on the transom (besides contant cleaning)?

[sailingdog]

Don't motor... Sailing produces no smog or soot...

[eherlihy]

Yes,

Frequently the soot is a sign that your engine is not running properly. Problems could include fuel mixture too rich, too big a prop, low idle, crappy fuel... I'd check it out.

Ed

[sailingdog]

Most common possible causes:

Plugged air filter or insufficient air flow to engine
Too much exhaust back pressure
Defective turbo/supercharger, if there is one—not particularly likely as most sailboat diesels aren't super/turbocharged.

Dirty fuel

Fouled injectors
Injection timing off

Prop improperly sized—too big
Heavily fouled bottom
Too many accessories being driven
Rope around propshaft

Assuming you've checked the prop sizing, haven't added any new engine-driven accessories—like a new refrigerator or alternator, cleaned the bottom of the boat and checked to see the prop shaft is clear. I would check the air flow and the air filter.

If the air filter and air flow to engine are good and the engine isn't overloaded... I would test it by using putting good clean diesel into a portable tank and then feeding the engine from the portable tank. If it is still blowing black smoke, then it is most likely a problem with the injectors—either they're fouled or the fuel injection timing is off.

I would also inspect the exhaust system to make sure it hasn't got a crimped or kinked hose or a hole in it someplace. This isn't all that likely, unless you've made changes near or to the exhaust system setup.

[bbistis]

Thx Dog... all good suggestions, but I don't see any of them actually pertaining me, except perhaps dirty (sp: old) fuel, because I sail 99.9% of the time and use less than a tank per year. My staining issue is not excessive, but more like common to just about every diesel boat/car I've ever seen. Trouble is I'm a neatnick, looking for an easier fix than cleaning and waxing. I think I'll just add the last 0.1% and sail all the time so I don't have to worry.

[sailingdog]

bb-

They have a wax that now contains PTEF, a form of Teflon, which is supposed to work pretty well. It might help make it so the soot doesn't stick as much to the fiberglass. PS magazine rated the stuff pretty highly... it's from West Marine... You can see it here.

[FrankLanger]

I had great success recently with Starbright's Black Streak Remover, available at chandleries, in removing black streaks and any exhaust stains--just spray on, leave for a minute, wipe off, rinse, wax. Worked like a charm!
Frank.

[sailingdog]

BTW, the Mr. Clean magic eraser sponges probably do a really good job at cleaning that stuff off the hull.

[resdog]

I used to have an old C&C 30 that always had an exhaust stain on the transom. There was nothing wrong with the engine. After watching the stern quite a few times I noticed the way the water flowed behind the boat created a backwash on the transom and would deposit soot that was on the surface of the water. That's beside the point, but I used Simple Green and a scrubber which effectively took the wax off the transom so yes I was constantly scrubbing it until I decided to ignore it. The only time I saw it was when I was in the water behind the boat.