What Is It?

I found this lying in the bilge, halfway between the front of the engine and the bulkhead. It's about two inches long and broken off on the end away from the nut. The shaft is about 1/8" in diameter and the nut is probably 3/8". Or, it could be metric, I didn't check.

The boat is a trawler with a single Volvo TAMD 41P engine.

99,9% certainty is not a part of Volvo Penta original. You need to try to look at possibly empty holes in the engine room equipment installations.


Unfortunately, I can not help you any more

Do you have any kind of hatch pulls on the hatches to your engine space?

I have those engines. I don't have any chrome plated or stainless crown nuts on my engines. Any Brass or bronze bolts are only in the Heat exchangers, maybe the aftercooler, but definitely not the block.
That doesn't mean this one wasn't added to yours by a PO, just reduces the likelihood that this part came from your engine.

After leaving the boat, it occurred to me that this might have come from the alternator. I'll be prepared to do a lot of exploring the next time I go back.


I have hatch pulls but they are screwed, not bolted.

It looks like a main bolt for a small electric motor, holding the end caps together to sandwich the motor housing. It would be an older unit as newer motors tend to have threads machined into one of the two end caps.

Greetings,
Mr. WK. The fact that one end is terminated in a chromed acorn nut with a non metallic washer suggests that at one time it was meant to hold down a fitting/panel that did not need to be very tightly torqued down and was in a visible area.
The missing end could have been simply threaded or terminated in a "head" of some sort (flat head, round head, hex head). Very unlikely that it was part of your engine...MY best guess.

As far as being stainless. Just doesn't look like it to me (wrong color).

RT Firefly said:

Greetings,
Mr. WK. The fact that one end is terminated in a chromed acorn nut with a non metallic washer suggests that at one time it was meant to hold down a fitting/panel that did not need to be very tightly torqued down and was in a visible area.
The missing end could have been simply threaded or terminated in a "head" of some sort (flat head, round head, hex head). Very unlikely that it was part of your engine...MY best guess.

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The valve covers on the engine have similar cap nuts but of course, being a Volvo, they are painted green. Also, none are missing.

Gdavid said:

It looks like a main bolt for a small electric motor, holding the end caps together to sandwich the motor housing. It would be an older unit as newer motors tend to have threads machined into one of the two end caps.

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I remember something similar on a macerator pump I once repaired. As I mentioned, I am hoping to find it's off the alternator which is pretty similar to a motor.

And of course, it's possible that it's been floating around for years and just now surfaced.

The acorn nut means it belongs to something meant to look pretty. A faucet, an engine or generator control panel, a valve manifold mount.

Look around for other acorn nuts on stuff as they are usually not used in singles.

1/8" dia brass bolt, soft washer, and 3/8" chromed acorn nut? I doubt it's anything serious. I doubt it's part of an electric motor or an alternator; not long enough and not usually acorn nuts. I agree the nut does not look like stainless. Not much corrosion so not from a wet item.

Guesses: off of a marine toilet; a cover for electric switch gear/charger/inverter; from some bit of discarded equipment; potable water filter;

I always wonder when I find washers, nuts, screws lying around.

At first look I would agree that it is off something that wants to look tidy given the head of that nut.

But on second look it looks like the bolt of a strainer basket. These are usually held down by wing nuts, but if the OP had dropped or otherwise lost the wing nut, he could very well have reached into his pile of nuts and found something to replace it with.

Check your strainers.

I just replaced several of these. They are Macerator pump bolts and are two different lengths. there is a stainless replacement bolt set available as the brass were problematical.

Looks like a strainer or pump assembly stud. Looks like the head is broken and remains the nuts, did you find the hex head anywhere near?

The Other Gary said:

I just replaced several of these. They are Macerator pump bolts and are two different lengths. there is a stainless replacement bolt set available as the brass were problematical.

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As I mentioned, that's what it looks like but there's no way any parts from the macerator found their way to where I found this part.

There was a comment about it being too short for something but since it's broken at the end opposite the nut, we don't know how long the rest of it is.

Thanks for all the suggestions. It's going to be really cold this weekend so I probably won't visit the boat until next weekend.

It is something someone threw in there to drive you nuts. A little like throwing a rigging pin or cotter pin on a competitor's sail boat deck before a race.

It's entirely due to bilge ferrets, they love to do this sort of thing to annoy you. You must learn to adapt and understand their games.

Stupid question, do you have any prosthesis? Maybe this does not come from your boat...

Greetings,
Mr. L_t. THAT'S the best question of the year (so far). You win the internet!

No, I do not.

Would it be my boat I would have said my wife lost a bolt but no that's not from her

Mystery Solved

I went to the boat and checked the alternator. No dice. Remembering that this looked like a bolt from a macerator pump, I checked the spare macerator and Bingo, that's where it came from.

The long version:

A year or more ago, I bought a spare Jabsco macerator pump. I put the carton in a large zip lock bag and stored it under the deck near where the battery charger and combiner are located. Also in the bag was a spare GPS antenna.

A few weeks ago I needed the spare antenna but when I opened the bag, I noticed that it was wet and the macerator carton was falling apart.

I took the macerator out of the carton and took it home so I could shrink wrap it in a food saver bag. At some point between opening the bag and taking the pump home, this part must have fallen into the bilge or gotten kicked into the bilge.

It must have been over torqued at the factory because the pump has never been installed or used.

I was able to contact the factory and it appears they must have had this problem in the past because the brass rods and nuts have been replaced with stainless steel bolts. The nice lady promised to send me a set at no cost.

The "Other Gary" wins! Probably won't go over well with the "main Gary" though.

Mystery explained, it was not from outer space after all

Great job solving the mystery, TF sleuths. Where else can you post a picture of a broken boat bolt and find the part it came from?

Heal, Love the new Surfing Manatee avatar.

FlyWright said:

Heal, Love the new Surfing Manatee avatar.

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Looks like Tom Hanks trying to escape that island.

healhustler said:

The "Other Gary" wins! Probably won't go over well with the "main Gary" though.

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The Main Gary is known as Arlene and she want's nothing to do with the macerator system. My department exclusively.

WesK said:

...It must have been over torqued at the factory because the pump has never been installed or used.

I was able to contact the factory and it appears they must have had this problem in the past because the brass rods and nuts have been replaced with stainless steel bolts. The nice lady promised to send me a set at no cost.

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Not over torqued from what I've seen. I too have found brand new, un used macerator pumps (plural) with broken brass studs. Not broken really. Corroded through. If you compare it to the pump you will find it is corroded through right at the paper gasket between the pump halves. I suspect they treat the paper gasket with an anti-poop chemical that eats the stud. I've gone to an industrial supplier and for very little money have bought SS threaded rod the same size, cut it to length and replaced all the studs on brand new pumps before installing.

If you have one of these pumps installed on your boat and it quits pumping, chances are a stud or two have come apart. Don't ask how I know this. LOL. Easy to fix with that SS rod.

Greg S

Greg S said:

Not over torqued from what I've seen. I too have found brand new, un used macerator pumps (plural) with broken brass studs. Not broken really. Corroded through. If you compare it to the pump you will find it is corroded through right at the paper gasket between the pump halves. I suspect they treat the paper gasket with an anti-poop chemical that eats the stud. I've gone to an industrial supplier and for very little money have bought SS threaded rod the same size, cut it to length and replaced all the studs on brand new pumps before installing.

If you have one of these pumps installed on your boat and it quits pumping, chances are a stud or two have come apart. Don't ask how I know this. LOL. Easy to fix with that SS rod.

Greg S

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The company is sending me stainless steel bolts to repair this. I should have asked for two sets. One for the working pump and one for the spare.