Serpentine Belt Issue?

[Yankees39]

Is this a Problem? My serpentine belt throws this residue / particles all over the back of the engine area (see pictures). residue is on all sides not concentrated on one area. I bought the boat last summer and about a month later my belt shredded. I replaced it with a Mercruiser belt but it still throws the residue. To be clear I am not having a problem with the belt nor the engine, the boat runs fine. It just gets dirty and i don't want to shred a belt out on the water and be stuck (I do have a spare belt in the boat now).

The boat is a 1999 21V 350 Mercruiser MPI MAG Serial # 0L390830

I have a friend who has the same boat but a 2001 with the same motor and his belt spreads the same residue and his belt has lasted 3 yrs and the one before that even longer, so that got me thinking maybe this is just what they do.

I know that Mercruiser had a recall on these motors to shim the lower bolt holding the alternator but my serial number doesn't fall into the range of the recall. So I'm not sure. Also not exactly sure how to make sure pulleys are all align.

Any thoughts?

[PaceWithGrace]

Is the residue greasy? Maybe something 's getting on the belt and getting flung everywhere? What about water from the deck or bilge?

[Yankees39]

It's not greasy. Just a powder. Also forgot to mention with the belt off the two idler pulleys spin normal and the alternator spins freely also. The impeller pulley spins with friction but that's normal due to the impeller.

[brett22i]

Had the same issue on a Marine Power engine. You either have a very loose belt or an alignment issue. Best thing is to try and shim it straight. Make sure to clean the flame arrestor often. That rubber belt dust gets sucked into the throttle body.

[jlavalley]

something is probably out of alignment. I think there maybe an automotive store that may rent a laser alignment tool that gates makes. You could also look to see if something has been replace or is not stock which may narrow down what is causing it

[chpthril]

Does it look like the alternator or any other accessories have been serviced or worked on? I would pull the belt and check all the pulleys for play.

[IDBoating]

I have gotten a bit of dust like that from Day One, but nowhere near that quantity. I suspect one of your pulleys is slightly out of alignment and slowing shaving the side(s) of your belt. Do you see wear on either side of the belt?

[Yankees39]

Thanks for all the replies. The tension-er pulley has some play but that's when the belt isn't on it, which is probably normal. The other Idler pulley at the top seems fine.

The alternator might be newer. When I place a level across the Crankcase pulley(I think that's what it is called, the big pulley in the middle) it is flush with the water impeller pulley but is about 1/8" difference from the alternator pulley (see picture even though it is kinda hard to tell).

There is more wear on the outside ribs (closets to Transom). I have never aligned pulleys before i might need to take it to someone to do that.

[scoot18]

That amount seems a bit excessive, it shouldn't throw out that much.

[chpthril]

Doesnt take much to get the belt riding up on the grooves and shredding it.

[JTs-rz2]

Was this issue ever resolved?

[Yankees39]

I replaced the alternator pulley and water pump pulley. The idler pulleys looked good no cracking and the crank case pulley and the round smooth pulley in the middle (sorry Im not good at the mechanic terms) I tried to clean the best I could. And I have definitely noticed a huge reduction in black particles on the walls and bottom of the middle sun deck pad. I feel cleaning and replace if pulleys definitely helped. Time will tell hopefully I get more than 8 months out of the belt.

[rostap]

Had the same problem with my 2000 21v. Replaced the belt with a Continental elite pro-v belt at the beginning of the year and so far runs much quiter and no trace of rubber.

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[Pro-Fab]

Old thread but for information sake. I have had this previously. I replaced the tensioner and idler pulleys to fix this. I also keep a spare pulley in the boat... it will leave you stranded. Both pulleys are the same part number. you can actually use one from Autozone.

[TeamAllen]

There is a TSB for checking pulley alignment. It may or may not help?
http://www.mercruiserparts.com/bulle...2003/EN_04.PDF