Diesel Fumes & Ventilation

[raycoker]

I have a 1987 303. Yanmar 16. I get a lot of diesel fume smell below when under power. The engine room is sealed well. I also noticed that I do not have any ventilation anywhere on the stern. It seems to me that I should mount an intake and exhaust vents on the stern and attach an inline fan to the exhaust with the hose down near the motor.

When I get back to the slip I always have to let it air out.

I am a novice and just got this pearson. I had the engine checked out by mech before purchase. It runs cool and well.

Please advise.

[Tim R.]

We have a yanmar and get absolutely no diesel smell in the engine compartment.

Venting sounds like you are simply treating the symptoms of a bigger problem. Could be an exhaust leak or a fuel leak. Better to solve it properly of it could be dangerous.

Venting is not a bad idea anyway but the intake is in the engine compartment so it creates a low pressure area that sucks air in from the cabin or a passive vent to the outside. Exhaust is on the transom.

[raycoker]

Thanks Tim

[Jetexas]

I agree. It sounds like an exhaust leak.

[beachmont]

Do you smell fuel or exhaust?

[asdf38]

Originally Posted by treilley

We have a yanmar and get absolutely no diesel smell in the engine compartment.

Venting sounds like you are simply treating the symptoms of a bigger problem. Could be an exhaust leak or a fuel leak. Better to solve it properly of it could be dangerous.

Venting is not a bad idea anyway but the intake is in the engine compartment so it creates a low pressure area that sucks air in from the cabin or a passive vent to the outside. Exhaust is on the transom.

So are you saying it's not necessarily to vent the engine compartment?

In previous years I sailed with the engine compartment open to the cabin. It's fairly recessed and the battery switch was placed within the compartment. So it was much easier to just leave the cover off (It's just a piece of wood and doesn't cut down on noise. Note, I never noticed fumes in the past). But as part of a re-wire I moved the battery switch out which gives me the option of actually using the cover.

Should I worry about venting? Of course it's far from air tight, there are openings to both cockpit lockers for wiring and engine controls which both have openings to the cabin for wiring etc.

[Tim R.]

Originally Posted by asdf38

So are you saying it's not necessarily to vent the engine compartment?

In previous years I sailed with the engine compartment open to the cabin. It's fairly recessed and the battery switch was placed within the compartment. So it was much easier to just leave the cover off (It's just a piece of wood and doesn't cut down on noise. Note, I never noticed fumes in the past). But as part of a re-wire I moved the battery switch out which gives me the option of actually using the cover.

Should I worry about venting? Of course it's far from air tight, there are openings to both cockpit lockers for wiring and engine controls which both have openings to the cabin for wiring etc.

Is your inboard engine gasoline or diesel? If your exhaust system is not leaking, the best reason to ventilate a diesel engine compartment is to reduce heat.

Venting a gasoline engine compartment should be obvious.

[Faster]

Such smells can come from exhaust leaks, as indicated, from hot oil leaks, and from blowby or having the PCV hose disconnected from the air cleaner/intake. Older engines that still run well can suffer from blowby which can overload the 'suction' system intended for them and result in hot oil fumes within the cabin space.

We had a half season of exhaust smells where no apparent leak existed. Last fall I removed the exhaust elbow and, despite looking solid parts of it were virtually porous. A new SS assembly and we're smell free again.

I do like the idea of a blower in the compartment to remove excess heat as Treilley suggests.. newer Beneteaus have them that run anytime the engine is running. An off delay function would be better still.