Cummins Marine Diesel Repower Specialists › Forums › Cummins Marine Engines › QSB 5.9 sea water pumps and stretchy belts

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  • February 1, 2018 at 4:24 pm #27737

    Troy
    Participant

    What is the difference between the stretchy belts for a QSB 5.9 380 hp and the QSB 5.9 420 hp ?
    I see they list them separately.
    Thanks

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  • February 2, 2018 at 8:13 am #27749

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Yes, pulleys are interchangeable and the belt is longer

    February 1, 2018 at 5:25 pm #27741

    Troy
    Participant

    Ok, thanks.
    So Iā€™m assuming itā€™s the same pump just a larger pulley and therefore a larger belt as well ?
    I have the 380ā€™s but Iā€™m getting ready to repower with a pair of 420ā€™s and have a spare pump and pulley and was wondering if they were interchangeable.

    February 1, 2018 at 5:19 pm #27740

    28Cuttyhunk
    Participant
    Engines: 6BT-220 QSB-5.9
    Location: Massachusetts

    Belts

    The QSB 480 & 420 use a larger sea water pump pulley than the 380, Thus the belt for a 480/420 would be loose on the 380.
    The reason for this is that the 420/480 turn higher RPM and the larger pulley slows the sea water pump RPM reducing the possibility of pump failure.

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