OMC 140/400 exhaust smell inside boat

[superbenk]

Since fall/winter is upon us, I'm considering some off-season repairs & remembered something that had been a problem during this past season. When cruising and at speed, we'd always get a pretty strong smell of exhaust inside the boat. I don't see any noticeable exhaust leaks inside the engine compartment, so I'm wondering where these fumes are coming from and what I can do about them. Are these just normal fumes kicked up from the exhaust coming out of the prop? The other place I'm wondering about is the seal between the intermediate housing & upper gearcase where the exhaust passes into the outdrive. It's a 30 yr old boat, so I'm sure this seal is original and old.

I'm considering replacing the impeller in the outdrive this winter as it's probably original (haven't seen any symptoms of a problem, but it's still probably due). Is there anything else I should look for to try and fix this exhaust smell? It's really not overwhelming, but it's noticeable.

As I stated, it's a OMC 140 w/ 400 Stringer on a 1980 Century 190 (see sig).

 

[Gary H NC]

Re: OMC 140/400 exhaust smell inside boat

Does the exhaust have a really rich smell? Any black smoke when you get on the gas hard?
Sometimes a rich condition is very noticeable inside the boat.

 

[superbenk]

Re: OMC 140/400 exhaust smell inside boat

Does the exhaust have a really rich smell? Any black smoke when you get on the gas hard?
Sometimes a rich condition is very noticeable inside the boat.

Not that I've noticed. It doesn't smoke at all.

 

[Daviet]

Re: OMC 140/400 exhaust smell inside boat

In the old days when we were trying to find an exhaust leak, we would run the boat and squirt a little fogging oil or ATF in the carb and watch for smoke. Just make sure to run the engine long enough to clear the engine before shutting down.