Need Part Number for 4-107 Alternator Belt

[GrowleyMonster]

My alternator belt is just gone. Obviously down in the bilge, which I can't get to. Westerbeast 4-107. Belt looks like it should be about 36" around and half inch wide. 100 amp alternator. Does anybody have a good NAPA part number? I used to be able to specify length and profile and get generic belts at autozone but they are all screwed up. They want vehicle make and model, only way they can look it up. I should have told them 1979 Bruce Roberts Offshore 44 aft cockpit sloop, fiberglass but I'm not that much of a smartass. Anyway I don't seem to have a spare and I found 22217 and also 12270 for part numbers in shop manuals for these engines. I'm not getting anywhere with those numbers.

[GordMay]

Westerbeke Part Number: 11918
#11918 ➥ https://www.westerbeke.com/Product/BELT/011918
4-107 Parts ➥ https://www.westerbeke.com/Category/...F776#viewparts
Item 22 ➥ Torresen Marine

➥ https://l-36.com/read_pdf.php?file=m...++Parts+Manual

[tkeithlu]

Once you've figured it out:

You belt is almost certainly a type "A".

The nominal outside circumference is about two inches greated than the effective circumference, so an "A-63" belt fits a 65" route. "AX" belts get the "X" because they have interior cogs, which let them flex to go around small pulleys.

Here's the entire inventory of v-belts; you can order what you want without messing with VIN numbers and paint names.

https://www.mcmaster.com/v-belts/v-belts-8/

[GrowleyMonster]

Originally Posted by tkeithlu

Once you've figured it out:

You belt is almost certainly a type "A".

The nominal outside circumference is about two inches greated than the effective circumference, so an "A-63" belt fits a 65" route. "AX" belts get the "X" because they have interior cogs, which let them flex to go around small pulleys.

Here's the entire inventory of v-belts; you can order what you want without messing with VIN numbers and paint names.

https://www.mcmaster.com/v-belts/v-belts-8/

<Face palm> Of course! I didn't think about Grainger or McMaster. Good call. Thanks.

I stayed up all night and found them listed by size at OReilly and I am to pick up a 36" x 1/2" tomorrow. I will see if it fits, and order more if it does, and order a different one, otherwise. I am actually expecting now that it will call for a 37" or 38" belt but hey, it's just eleven bucks.

[GrowleyMonster]

Originally Posted by GordMay

Westerbeke Part Number: 11918
#11918 ➥ https://www.westerbeke.com/Product/BELT/011918
4-107 Parts ➥ https://www.westerbeke.com/Category/...F776#viewparts
Item 22 ➥ Torresen Marine

➥ https://l-36.com/read_pdf.php?file=m...++Parts+Manual

Thanks, Gord. I just pulled the trigger on the one with the 11918 part number. I also got a generic belt of hopefully the correct size on order with OReilly.

[BruceS]

Are you sure of size of the alternator? Might be a bigger one has been put on it? My old 4-108 was a 'B' & had an alternator with an "A" pulley & half an inch off line. Wondered why it was chopping the guts out of the belts! Not sure why yours would have that size on it?

[GrowleyMonster]

Originally Posted by BruceS

Are you sure of size of the alternator? Might be a bigger one has been put on it? My old 4-108 was a 'B' & had an alternator with an "A" pulley & half an inch off line. Wondered why it was chopping the guts out of the belts! Not sure why yours would have that size on it?

Upgraded a couple years ago when I first started rewiring the primary electrical system. I wanted a bigger alternator because I was adding a watermaker and a windlass.