Smoke in exaust

[Dixon Hemphill]

Recently I have noticed white smoke in the exhaust of my CD28 which has a Yanmar 2GM20F engine. Somewhere I read an article about colors of smoke coming from marine diesels --- white, blue black etc. Can one of you experts tell me what white smoke indicates and how best to eliminate it?

[Jim_B]

White smoke might indicate antifreeze in the combustion. If it is antifreeze related you'd notice losing coolant fluid and perhaps a unique exhaust smell. This could be related to a head gasket problem and is typically confirmed by a blow by or pressure test.

Is it possible that what you are seeing is just steam and does is disappear after the engine gets up to operating temperature?

[Dixon Hemphill]

The antifreeze level remains the same. The smoke is not dense but quite light however I am sure there has been no color to the smoke on previous outings.

Have you ever seen the list of causes when various colors of smoke appear?

[Jim Evans]

Hi Dixon,

I had similar symptoms with my Yanmar 3GM30F. It turned out that my mixing elbow was all clogged up, and replacing it fixed my problem. If you've not changed yours in a few years, I'd check it for clogged passages.

[psjanker]

Going back to my Army Armor days, my experience is that white smoke is what one got when injecting raw unburnt diesel into the exhaust manifold. My guess is that you somehow are getting too rich a fuel mixture.

V/r

Pete

[TerryO]

I have been concerned about the same issue on the 1GM10 in my boat. It only has about 80 hours and I get white wispy smoke as well. I chocked it up to steam from the warm water but there is also a burnt oil smell. The engine is not going through oil so I am wondering if old fuel might have something to do with it. This is my first experience with a diesel. The stern of the boat gets covered in soot which is annoying and from what I have read not that uncommon on the 25D. I would really like to minimize it though.
Thanks.

[Dixon Hemphill]

To Jim Evans, I had a brand new mixing elbow installed last year and haven't used the boat more than 40 hours since.

To TerryO, My fuel is about one year old, maybe two but I doubt if it's old enough to cause white smoke.

I plan to do more motoring on the 4h of Aug --- maybe the white smoke will lessen after a few hours.

Thanks for your comments

[Sea Hunt Video]

A diesel mechanic I trust told me the following a couple of years ago:

white smoke - water
blue smoke - oil
black smoke - fuel

I assume there are variations to the above. He also knew I was not the sharpest knife in the drawer so he probably kept it very simple for me.

[GeorgeV]

White Smoke generally is the result of 1 of 2 things, Steam or Unburned Fuel.

If you let the engine run a few minutes and then put your hand near the exhaust for a couple of moments if it is unburned fuel you should smell diesel fuel on your hand, if not it is steam (water) in the exhaust.

The most likely cause I have found of steam in the exhaust is a clogged heat exchanger or exhaust manifold. The exhaust manifold has a water jacket around it to cool and dampen the exhaust noise before the raw water is pushed out through the mixing elbow on the exhaust hose. The heat exchanger is like a radiator on your car where raw water is pumped through a coil and cools the antifreeze that actually surrounds the engine. You should see a good stream of water coming out of your exhaust and if one or the other is clogged you won't be getting much flow out of the exhaust and you may also be experiencing the engine running warm or overheating. The heat exchanger is not too difficult to clean out, but the exhaust manifold is another story (I just had to replace my exhaust manifold as it was nearly completely blocked up and had a crack in it).

Good Luck

[roger]

Hi Dixon---My 28 Oday had white smoke one time. Very uncomfortable feeling not knowing what caused it. Turned out to be the raw water strainer got clogged with eel grass. Cleaning the strainer made the exhaust no longer white. Hope you have no major issues with the engine. Roger

[Neil Gordon]

Turned out to be the raw water strainer got clogged with eel grass.

That's another vote for steam.

[GeorgeV]

Sometimes it is the simple things we should look for . . glad to hear you back up and running with no steam.