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Making Alternator Belt Tension Easy

Discussion in 'Engines and Propulsion' started by Michael Davis, Nov 5, 2017. Add this thread to a FAQ

  1. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    It's just the make of the belt. I have two spares on board, one is not notched and the other has inside notches and this one is as you see it.
     


  2. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    I've replaced a few like that in the papermill. Usually alinement, tension or old age.
     


  3. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    That looks great. Easy to get at and adjust. I think I have to much junk on the front of my engine to do that.
     


  4. Gunni

    Gunni

    Joined Mar 16, 2010
    4,402 posts, 586 likes
    Beneteau 411 Oceanis
    US Annapolis
    Pateco, that is one worn out belt. See how it sits low in the pulley groove? Your belt replacement schedule is way too long. The belt overheated, developed a crack and then started to delaminates. If you don’t like changing belts get a serpentine belt kit upgrade. It will provide the opportunity to drive a much more powerful alternator too.
     


  5. pateco

    pateco

    Joined Aug 12, 2014
    1,445 posts, 235 likes
    Hunter 31 (1983)
    US Pompano Beach FL
    Good to know. That belt has been on for just about 1 year. Maybe I need 6 month replacements
     


  6. jssailem

    jssailem

    Joined Oct 22, 2014
    3,512 posts, 735 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    Chip ( @pateco ) if not replacement at the least inspection. perhaps inspection monthly will lead to 6-8 month replacement schedule.
     


  7. jviss

    jviss

    Joined Feb 5, 2004
    2,109 posts, 139 likes
    Tartan 3800
    US Westborough Westport, MA
    I might argue "precise enough," but certainly not accurate. Or maybe not even precise. How do you know?
     


  8. jssailem

    jssailem

    Joined Oct 22, 2014
    3,512 posts, 735 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    You are linguistically correct. I say mea culpa...
    How do you know if there is enough salt on the food? Like crowd sourcing. Do it. adjust. do it. adjust. Eventually you will know when you are "close enough". I know that my engine is not "precise" and that there is enough flex in the multiple parts associated with the belt that as soon as it is adjusted and the engine is started, during the belt movement, the belt will be in or out of adjustment.
    So I go with "close enough" and inspection to maintain performance.
     


  9. jviss

    jviss

    Joined Feb 5, 2004
    2,109 posts, 139 likes
    Tartan 3800
    US Westborough Westport, MA
    John, I didn't mean that. I meant that the mind fools itself using the twist or press method.
     


  10. ice breaker

    ice breaker

    Joined Sep 11, 2011
    200 posts, 14 likes
    Hunter 41
    US lake superior
    I would strongly recommend a notched belt.

    I have a 7 year old notched belt that has about 700 hours on it and is still going strong. Original belt was not notched and it was filling the engine compartment with belt dust. It was still working when I removed it, but it was tired after only about 150 hours of use. I find that the notched belt can be looser and not slip, whereas the smooth belt required attention to make sure it was correctly tensioned.
     


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  11. pateco

    pateco

    Joined Aug 12, 2014
    1,445 posts, 235 likes
    Hunter 31 (1983)
    US Pompano Beach FL
    I replaced it with my spare smooth belt, but I have three of the cogged belts arriving today.
     


  12. mm2347

    mm2347

    Joined Oct 21, 2008
    162 posts, 10 likes
    oday 222
    US niagara
    I worked in a foundry as a maintenance mechanic. Much of the equipment was belt driven. We found that the codded belts had better bite and took slightly less tension before slipping (usually noticed at startup) but the trade-off was a more rapid shive wear. We based this on how many drive belt changes per shive change. I don't remember the number but it was enough to make a difference.
     


    pateco likes this.
  13. Gunni

    Gunni

    Joined Mar 16, 2010
    4,402 posts, 586 likes
    Beneteau 411 Oceanis
    US Annapolis
    Oh my, that is fast wear; assuming reasonable engine hours. Something else might be going on, alignment, alternator bearings, tension, etc. I’m seeing a lot of shine on the belt sides.
     


  14. jssailem

    jssailem

    Joined Oct 22, 2014
    3,512 posts, 735 likes
    CAL 35 Cruiser
    US Salem, Moored Port Everett WA
    The shine would lead me to believe that you have experienced the squeal cry of the belt from time to time.
    This would mean that the belt can not drive the other pulleys to which it is attached. The belt is turning but the pulleys are not. Thus Squeal... Alternator overloaded, bearings on the pulley shafts not allowing the shafts to turn freely, A problem with the water/coolant pump, or just not enough tension on the belt (maybe worn or breaking down).
    Just a few ideas.
     


  15. pateco

    pateco

    Joined Aug 12, 2014
    1,445 posts, 235 likes
    Hunter 31 (1983)
    US Pompano Beach FL
    John,

    This is a raw water 2gm 13hp so this belt only runs the Alternator. There is a second smaller belt for the raw water pump. The new cogged belts are supposed to arrive today. I will keep a better eye on them.
     


  16. pateco

    pateco

    Joined Aug 12, 2014
    1,445 posts, 235 likes
    Hunter 31 (1983)
    US Pompano Beach FL
    We sail a lot, and have to motor 45+ minute out, and 45+ minutes back in, so there may be quite a few hours in one year. How many hours should a belt last?

    (PS the engine hour meter the PO installed still reads all zeros so it is hard to tell.)
     


  17. Michael Davis

    Michael Davis

    Joined Jan 5, 2017
    273 posts, 70 likes
    Beneteau First 38
    Ca Saturna Island B.C. Lyall Harbour Saturna Island
    How often do you change the one in your car? I've never kept track of hours of run time at work but some go several years running 24/7.
     


  18. Maine Sail

    Maine Sail Moderator

    Joined Feb 6, 1998
    10,405 posts, 338 likes
    Canadian Sailcraft 36T
    US Casco Bay, ME

    If depends upon:

    • Alignment - Just because it's a factory alt does not mean it is correctly aligned
    • Alternator Load - 3/8" and 1/2" belts can't handle high loads for long duration's
    • Battery Depth of Discharge & Bank Size - Bulk charging places extreme loads on the belt
    • Pulley Type - Stamped pulleys seem to allow more slippage than billet machined pulley's
    • Belt Wrap - belt wrap on the alternator pulley is often less than ideal on many marine engines
    • Rust and Pitting - Condition of the pulley vee has a lot to do with belt wear
    • Belt Tension - If the belt wears and is not re-adjusted regularly the belt will slip and wear out sooner
    • Glazing - If the belt has been slipping, often not audibly, the belt will glaze and not be able to hand the same load
    I have seen 1/2 & 3/8" belts that can barely last 30 hours because the owner has simply installed too much alternator for single v-belts capabilities.
     


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  19. pateco

    pateco

    Joined Aug 12, 2014
    1,445 posts, 235 likes
    Hunter 31 (1983)
    US Pompano Beach FL
    I have the standard Hitachi 55 amp alternator with a stamped pulley. I have a spare 80 amp alternator with a machined pulley, and the bracket to mount it, but have not done so yet, as I was worried about using just a 1/2" belt for this. I have looked at the Balmar Serpentine Pulley Conversion Kit 48-YSP-3GM-C, but $453.60. for two aluminum pulleys and a belt just feels like too much for my budget now based upon the other projects I need to work on on the boat.
    Balmar Pulley Kit.png
     


  20. Ken13559

    Ken13559

    Joined Oct 29, 2005
    1,817 posts, 48 likes
    Hunter 326
    SG Singapore
    Good to check that there's no rust on the pulley where the belt sits in. Rust will wears belt and create belt dust.
     



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