white smoke

[Molly]

I have a 2006 Mainship T34 with 950 hrs on twin Yanmar 220 HP
I have the boat less than a year and have gone cruising a bunch.
I noticed the last trip I made the transom seemed a little more dirty than usual. Like the exhaust increased. It was black soot. I cleaned and waxed the transom. I went out of town for 2 weeks, turned off the battery switches and locked her up. while I was gone, we had a very windy and rainy storm for the good part of 1 day.

Started her up and there was a good amount of white smoke and the engines ran a little ruff for a few minutes. The white smoke really decreased after the engine were up to temp. They seem to run OK. I ran up the RPMs to 2500 or so and let it idle at 1400.

Is this normal? Maybe water got forced into the exhaust from the storm? By sitting for 2 weeks, the oil would be completely drained to the bottom.

Is there an easy way to run a few tests before I call a mechanic?

 

[Capitaine R]

We have had a few cold mornings here in good old PG, what was the ambient temperature when you started her up? Diesel will smoke white if they are cold. I had a few tractors belching some white smoke in the am but cleared up fairly fast once they warmed up.

 

[Lou_tribal]

White smoke at cold start that then dissipate is nothing unusual.

L

 

[DavidM]

The black smoke on the transom could be caused by the bottom or props getting dirty which requires the engine to produce more power to reach the same speed as before. This causes unburned fuel and smoke.


It could also cause the rough idling when you first start it up after sitting for a while. The injectors are a bit fouled which also causes white smoke which burns off after a while.


So get the bottom cleaned and take it out for a hard run to burn off all of the accumulated junk inside.


If my theory is correct it will run clean afterwards and start easily with just a little white smoke that will quickly clear.


David

 

[Woodland Hills]

Try an Italian tune up. Run her up to maximum for a half hour or more and see what happens the next time you do a cold start. Once the temperatures get below 50 you can get a bit of white smoke on start up, the black soot is another thing altogether and not related to the cold weather IMHO. Neither are a serious problem at this stage, but your boat is trying to speak to you and you seem to be listening.

 

[Flybull]

White smoke at startup is actually unburned fuel... common for diesels when starting cold especially if no pre-heat. Cold starting is a very inefficient burn in the cylinders, but as long as they clear up relatively quickly, can be a normal occurrence.

That being said... you've added two other symptoms being the excess (in your observation) soot on the transom and rough running after start up. These could be indicative of other issues... mainly a possible injector problem.

An injector issue can give you excessive black smoke under load (more noticed on transom) and can dump more fuel during cold start (more white smoke/unburned fuel).

Do you have block heaters? Do you notice more black smoke underway, under load? How's your WOT RPM?

 

[BruceK]

White smoke at cold start that then dissipate is nothing unusual.

L

Especially in a Papal election.

 

[Lou_tribal]

Especially in a Papal election.

Lol, good one!

L

 

[Alaskan Sea-Duction]

as mentioned, cold weather and glow plugs (if installed) not working can also be the cause and normal.

I have 3208T/A and they smoke on start up all the time. I either clear the mosquito patch or drown out a blow boat with start up....