Smell of rotten eggs from genset

[nhuyck]

I have a Kohler 7.5 EKD in a 2015 Cruisers. I just bought the boat and the generator had 5 hours on it when I bought it. The issue I am having is a horrible rotten egg smell upon start up of the generator. It will smell like rotten eggs for about 5 minutes. I took the exhaust line apart from the sea exhaust exit at the boat all the way back to the outlet at the genny and flushed the line thinking there might be a dead animal in it. Still happening. I’m guessing since this genset has a catalytic converter, I have an issue with that. Anyone else have this problem that they have worked through?

[Sailmonkey]

Catalyst needs to be heated by the exhaust to work properly. Stand behind any late 90’s to mid 2000’s ford vehicle and you get the same smell.

I don’t think you have a problem.

[four winds]

Welcome to the forum, nhuyck. (3 stooges, right?) nhuyck, nhuyck, nhuyck.

Catalytic converter on a genset, that is a new one for me. But I think you are correct to suspect it as the cause. When they first put them on cars years ago they all smelled like sulfur, all the time in fact.

Maybe it has to heat up before it "catalyzes" properly.

[a64pilot]

I bet putting a Cat on a wet exhaust Marine engine is some kind of feat.
First Cat gets hot, very hot, and of course you can’t inject water until after the Cat.
I’d be interested in seeing that set up.

[ShellBack89]

If you’re on FB we have a Cruisers FB page. Many good people with knowledge on CY boats.

[CatNewBee]

rotten eggs smell is usually a sign of boiling lead acid batteries...

[Chuck Hawley]

Is it possible that you're smelling the result of decomposing marine growth in the raw water circuit of the genset, which causes that terrible H2S smell? This is so common on infrequently-used marine heads that it seems like it could be your problem as well. I'd pull the intake line and either replace it or soak it in a strong cleaner (or maybe vinegar, which seems to be the go-to chemical for so many cleaning jobs) and see if that helps.

Cheers,

Chuck

[thinwater]

This is a gasoline powered genset (unusual). Yup, it is probably running rich, which will eventually burn the catalyst.


If you can smell the batteries you are seriously over charging.


Sulfur smell in raw water from marine life is rare because the heating tends to sterilize it.


I'm betting it's a combination of warm-up and a fuel mixture problem.

[a64pilot]

From just looking at it, it appears the Cat is water cooled, if not electrically heated, that could delay time to “light off”, which may mean what you have is normal.
The generator is fuel injected, so I’m not sure the mixture is off, could be, but less likely than if it were carbureted.

[thinwater]

Originally Posted by a64pilot

From just looking at it, it appears the Cat is water cooled, if not electrically heated, that could delay time to “light off”, which may mean what you have is normal.
The generator is fuel injected, so I’m not sure the mixture is off, could be, but less likely than if it were carbureted.

I bet you are right about the water cooling jacket and added mass delaying light-off. Not a car problem.

[W3GAC]

My money is on there is iron/ steel reacting with hot or cold salt (or fresh) water. Those of us living in country on wells w/o city chlorine periodically get horrible rotten egg smell from their well pressure tank and/ or hot water heater. No, heat does not kill the foreign growth that somehow gets started... even in a closed system. We have to sterilize the system with bleach every few to 4 yrs as it returns. I’d suggest during your winterization that’s coming up to add a step of running few gallons of water w/ bleach through the gen/ wet muffler and let sit overnight and flush out with water/ whatever you winterized with. Exact same thing can happen in water tank, especially Last ic ones.

[roland stockham]

When salt water sits in a pipe for a while you get this. Same with heads and salt water showers. It is cause by hydrogen sulphide being liberated. If you run the geny weekly it probably wont happen and is good for the engine.Otherwise it is harmless

[Cadence]

Originally Posted by a64pilot

I bet putting a Cat on a wet exhaust Marine engine is some kind of feat.
First Cat gets hot, very hot, and of course you can’t inject water until after the Cat.
I’d be interested in seeing that set up.

Me too! The best thing to do with one of them, is drill a hole up through the exhaust pipe and shake out the pellets. Or replace it with a section of pipe.

[a64pilot]

Originally Posted by thinwater

I bet you are right about the water cooling jacket and added mass delaying light-off. Not a car problem.

Well, it is actually.
US automobiles used to have their Cats very close to the engine so that exhaust heat would light them off quicker, you only have so many seconds after starting before you must pass emissions testing. Remember how 1970’s cars would race the engines when cold?
Then standards got even stricter and they are now I believe electrically heated to get up to temp even faster.
Then you have the Prius and other Hybrids that with their on and off engine running must still pass emissions somehow. I believe they are electrically heated, and strangely the Prius cools its Cat with engine coolant.
Actually what it’s doing is harvesting the heat, cause one of the major issues with hybrids is getting the engine warm, and keeping it warm.
In cold weather the Prius gets much worse mileage, cause it will run the engine just to keep it warm, even when it doesn’t need it for propulsion.

Although I never knew of a Cat equipped generator, motorcycles yes, but not generators.
I wonder how outboards get away with not having Cats?

[Cadence]

If I am not mistake catalytic converters got so hot that they could melt and ignite asphalt, under autos, and were band from oil refineries. Some refinery worker of the time might verify this or call it BS.