Puffs of smoke

[R.B.]

Just thought I would poll the group.

I have not used my motor much in the last year that we have had our boat maybe 10 hours. We just finished a week long cruise in the North Channel and I put about 50 hours on the motor. I noticed small puffs of whitish gray smoke and the slight smell of diesel. I was running at 2500 RPM (6.5 knots SOG via GPS). I have a new tach so it might not be calibrated. My max revs are around 2800 RPM (forward gear), the manual says 3000 is the max so I think I am close.

Do any of your boats have puffs of smoke or the slight smell of diesel?

[Bob MacWright]

That sounds fast, I think I get 5.2 kts at 2500. You may be over-reving the engine a bit. This makes sense, because I think white smoke is a sign of engine overloading.

[R.B.]

The speed at 2500 RPM is contingent on the conditions. With a head wind (again depending on the speed of wind) I slow to about 5.8 knots SOG. I will see at what speed the smoke disappears. I have always heard that diesel engines need to be worked and that they should be run at about 90% of the top RPM. Since mine is 2800, 2500 seems about right. Anyone else have any observations?

Thanks

[Triumph]

White smoke is probably OK. I'd question what the motor does at idol, especially after a cold start. Blue smoke is not good, black smoke is over working the engine, and is not good for long periods, but white smoke and smell isn't bad. If anything it may be incomplete combustion, meaning you have a fuel injector issue perhaps. Another sign of this is fuel rainbows on the water at idol speed in the slip. All just guesses with out seeing it, best to ask mechanic to look at the smoke.

[R.B.]

At idle and cold start I don't get any smoke and there isn't any fuel in the water. I will check this weekend and see at what RPM I start to get the smoke. The engine does not sound like it is laboring and does sound smooth and healthy.

[Hans Grasman]

Ralph
I just came back from a few days on Charlotte Harbor in SW Florida.
I also experienced the white smoke (steam like) situation. We had very damp whether and heavy fog and I noticed small puffs of white smoke at 2500 rpm. Very little or none at idle or slow speed.
Checked the manual and under engine trouble shooting it only had two references to white smoke. 1. Cold engine or defective thermostat. 2 Injectors.
I thought maybe the first day it was caused by the damp weather but the second day was dry and sunny.
Have you already followed up with a mechanic and if so what caused the white smoke?

[R.B.]

Hi Hans,

No I did not get a chance to cruise for any length of time after our cruise to the North Channel, and our boat came out of the water early this year. So I will have to take a look at it in the spring time. Considering how few hours I have on the engine, I would be surprised if it was a thermostat (my temps look normal) or the injectors. I have under 60 hours on my engine.

[Hans Grasman]

Ralph
Thanks for reply. I have 385 hrs on mine. I did replace the impeller just before the white smoke started to come out.
The impeller after 385 hrs looked and felt like new. I kept it just in case
the other one fails.
The manual does not say that anything bad can happen with a little white smoke.
Will talk to a mechanic here in Florida.
Hans

[Hans Grasman]

The puffs of white smoke are no longer there. The problem resolved itself.