Exhaust soot on transom

[AT Phillips]

Exhaust soot, but no mention of exhaust odor.....perhaps the soot is belt dust?  I believe a misaligned alternator belt can create quite a mess.  Mine sure did!!! 

[Les Luzar]

Ron and Ken:
Thanks for the suggestions regarding the white smoke I am experiencing from my exhaust. I will look into each probable cause and go from there!

[rmbrown]

Is love to hear what you learned.  In the last 9 months, I've taken mine from NC up to the Chesapeake (summer), then down to Key West, and I'm now in the Bahamas.   My transom is pretty dirty looking.   I see smoke all the time but struggle to pinpoint color.   If pushed, I'd say white.  Maybe gray.  Photo attached.

Not burning oil.   I check every day. Add when necessary but the amount is pretty small. 

[Ron Hill]

Mike : Your picture looks like steam or might be white smoke to me.

As far as soot on the transom - you'll always get some soot even with a perfectly running engine!!!

Adam : I'd say it is impossible to get belt dust into the exhaust system; unless you are talking about belt dust being so sever that it is clogging the air filter???  Then I believe that the exhaust would be dark smoke!!

A few thoughts

[Jim Hardesty]

I see smoke all the time but struggle to pinpoint color.   If pushed, I'd say white.

I believe if the smoke dissipates quickly its water vapor (white) if it lingers it's oil smoke (dark). 
Jim

[rmbrown]

Well... I've never noticed the soot before this year, but then I've run it about 400 hours in the last 12 months!

It disappears quickly enough so maybe water, but not sure it that's good or bad.

I had to run at 1800 rather than my normal 2250 today (dodging coral heads on the grand bahama bank) and noticed that it's just the occasional puff at that speed.

[Jon W]

Is the coolant level staying full or are you adding coolant?

[rmbrown]

I've added maybe 2 cups in the last year.

[Jon W]

The good news is you don't seem to be burning oil or coolant. Doesn't answer your question though. The smoke in your photo looks like steam to me too. Is your raw water discharge at the transom flowing normally for your boat?

[rmbrown]

Well, I believe it's flowing like it has since I got it so far as I can tell.   At first, it over heated if I pushed the throttle but cruised fine at 2k.  I've replaced most everything now though... that turned out to be a combination of a failing thermostat cap and a terribly clogged heat exchanger.  Yesterday I noticed that it sat right on 165 at 1800 but at 2250 it was more like 185.

Mike

[Stu Jackson]

Mike, I went back and reread this thread.

You just mentioned operating temperatures.

What temperature thermostat do you have installed?

[rmbrown]

165... and it's opening on time.

[KWKloeber]

Capt Mike

My best guess not being hands-on (sorry, I just realized that I missed your prior email asking if I wanted to tag along) is that you are looking at steam, you're just at the data point that with warmer seawater, cooling water exiting the muffler is not quite as cooled-off as with cooler seawater or using the Sherwood pump.  Nothing to worry about.

if you're getting soot on the transom (IMO) it's due to something else.

-k

[rmbrown]

I guess it'll eventually get worse and be easier to diagnose.

Too bad you missed that invitation.   I figured it must have gone to junk. ;)

[Ron Hill]

Mike : I believe that on days where there is a higher humidity, you'll see more steam than on low humidity days.

Also your soot may be generated by the throttle setting that allows more (than usual) fuel from the injection pump??

A few thoughts