rotten egg smell in engine compartment.

[CaptTom]

Yes, batteries outgassing can produce that hydrogen sulfide smell. I get the hydrogen part, and someone somewhere explained the sulfide part, but at any rate I've smelled it when a charger was over-charging or the batteries were going bad. A couple of times people were impressed when I stepped aboard a boat and instantly diagnosed that problem. It's a very distinctive smell once you've experienced it.

The other guess, sea (or lake, or river) water sitting too long can also do it. This is from decaying plankton and other life forms in the water. In my experience, rain water standing too long will produce a moldy or musty smell, not a rotten egg smell. But maybe everybody is sensitive to different smells.

[tarian]

Agreed it smells like batteries have had the same smell from a battery leaking by being over charged by charger, the smell is quit distinctive rotten eggs

[atoll]

the good news is you don't have the corona virus,otherwise you probably would not be able to smell what ever it is..........

[er9]

Originally Posted by atoll

the good news is you don't have the corona virus,otherwise you probably would not be able to smell what ever it is..........

Lol...now I'm worried if i get it and loose my smell, the hydrogen gas will accumulate, blow up and blow me to smithereens. I guess that it is one deadly virus.

[PaddyMac]

Have you checked your engine oil for possible source of the rotten egg smell. Bio contaminated engine oil from sea water could also give off an rotten egg smell. Is your oil emulsified?

[er9]

Originally Posted by PaddyMac

Have you checked your engine oil for possible source of the rotten egg smell. Bio contaminated engine oil from sea water could also give off an rotten egg smell. Is your oil emulsified?

thanks...i will check on the weekend when im back at the boat. i havn't run the engine in a couple of months though.

[skipbern]

Agree with all the comments above especially testing the batteries. The only other thing to check is if a through hull may be leaking fluid resulting from seawater having got into the core in the hull. Not exactly a rotten egg smell but similar.

[er9]

Originally Posted by skipbern

Agree with all the comments above especially testing the batteries. The only other thing to check is if a through hull may be leaking fluid resulting from seawater having got into the core in the hull. Not exactly a rotten egg smell but similar.

thanks, all thru hulls are dry and hull is solid grp. no standing water anywhere or accumulated little wet spots. inside hull is bone dry.

[Mike Banks]

Putrid bilge water or an overcharged battery.

[NorthernMac]

I thought west marine batteries always failed after 11.9 months

[Jim Cate]

they are west marine/ sealed lead acid start batteries.

Being they are sealed batteries, less chance that they are the source of the H2S smell. I too suspect stagnant sea water accumulating somewhere unseen and rotting.

And for some of you worry warts, Hydrogen does not smell like rotten eggs... Hydrogen Sulphide does, so outgassing from high voltage charging ("gassing") won't produce the smell that is reported.

Jim

[Wotname]

Originally Posted by er9

Lol...now I'm worried if i get it and loose my smell, the hydrogen gas will accumulate, blow up and blow me to smithereens. I guess that it is one deadly virus.

More importantly, if you can initially smell H2S (rotten egg gas) and then shortly after you can't, get to known fresh air ASAP.

H2S can be detected by smell at very low concentrations (around 0.0005 ppm) but higher levels (around 100 ppm) quickly deadens the sense of smell. Personal gas detectors will alarm as low as 5 or 10 ppm.

While very low levels (well below 0.1 ppm) can be tolerated indefinitely, very high levels are deadly. It is as toxic as CO and will kill you with a single breath at 1000ppm.

[bongo]

I’d look at the alternator regulator/battery charger over-charging the batteries. (Had it happen on a Porsche 911).

I’d also look at bilge/ballast water, (sea water), which is full of micro-organisms. They will eventually sour. (Alternating voyages hauling molasses and ballast water in the same tanks, the smell will knock-your-socks-off.

[billdomb]

Originally Posted by er9

i noticed a slight rotten egg smell in engine compartment couple weeks ago when i opened up the cockpit locker and had the engine room opened up. figured it was just marina smell. opened up engine compartment and cockpit l....

Rotten egg smell is usually hydrogen sulfide (which, incidentally is as dangerous as cyanide in quantity). Usually comes from bacterial activity and usually requires water.

Using a small ozone generator might help expunge the odor, but need to look at chronic moisture sources, I think.

[er9]

Originally Posted by billdomb

Rotten egg smell is usually hydrogen sulfide (which, incidentally is as dangerous as cyanide in quantity). Usually comes from bacterial activity and usually requires water.

Using a small ozone generator might help expunge the odor, but need to look at chronic moisture sources, I think.

thanks bill. i found the source of the smell and fortunately i dont think its the batteries after all.

there is an overflow pond about 1/5 mile from me to windward. I thought i'd noticed the smell before (im new to this marina). well ive been at the boat the past couple of days and its been warm and stagnant and the smell has been horrible. a neighbor confirmed its the containment pond which is pretty gross.

i was at the boat yesterday during one of these smell spells, closed up the boat and left for a few hours. when i came back there was no longer the smell outside but when i opened up the boat it smelled pretty bad.

i think what was happening was this bad air got into the boat when i wasnt there, dissipated in the cabin and probably lingered a while longer in the engine compartment. when i opened it up i smeeled it and though batteries.

it could still be batteries and i will monitor them closely to be sure but now i dont think so...