Exhaust Problem

[captaingary]

I have a problem with exhaust gas that someone else may have encountered before. I get a serious amount of exhaust fumes in the boat. The problem seems to have started in the last 2 years although it may just be that more additive has been put in diesel the past few years so carbon monoxide could be detected easier. My wife has complained about the odor but I have been telling her it is normal but it is very bad.

[Mike and Theresa Vaccaro]

Dear Gary,

Check your exhaust riser or muffler hose connection for exhaust leaks.  Lots of discussion on the board about changing risers.  See "Exhaust Riser" disscussion from the last couple of days.

Best of Luck,

Mike Vaccaro
"Spirit" '88 Hull 563

[captaingary]

I should have explained that the exhaust fumes are coming from the outside and not the inside.

[Ray & Sandy Erps]

If you've added a dodger just prior to experiencing the external exhaust smell, I'd suspect a back eddy in the air flow.  This is our first boat with a dodger and the exhaust fumes get a little strong sometimes.  If it's not too cold, we crack open the windscreen to let a little air flow through.

If you've always had the dodger, I'd check a diesel engine trouble shooting guide for the symtom of black exhaust smoke, usually associated with inlet air restrictions or poorly atomized fuel from the injectors to name a few.

[shekinahsailor]

A partial solution (that has been discussed before) - I mix 20% bio diesel with my regular and it totally replaces the original diesel smell with a mild "french fry" smell. Bio fuel is a hot discussion like politics but I've opted for it and believe it's improved my engine smoothness. Granted, this only masks rather than solves and you might have other problems that need addressing such as fouled injectors as Ray suggests.

[captaingary]

A followup on this. I put new injectors in and removed the outside cover of the silencer to allow more air in. The odor is still very strong. I have heard from 3 different people that extending the exhaust with a small piece of stainless tube and rubber hose to get the exhaust underwater would make a bif difference. Has anyone heard of this type of a fix? My understanding is that the open transom is much more proned to get the gases circulating back into the cockpit.

[Vic Suben]

For informational purposes.

Carbon monoxide is a colorless, odorless gas.  If you become aware of it at all it will be because you get a headache, fill dizzy or nauseous, become disoriented, or just pass out.

Probably the odor you perceive comes from unburned carbon or other fuel additives.