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Identifying the Alternator & Serpentine Belt on the QSB 5.9

Which serpentine belt do I need on my Cummins Marine QSB 5.9 engine?

Engines with 19SI alternators use the ORANGE BELT. 

Early QSB - 19SI Alternator
Early QSB – 19SI Alternator

Engines with 21/22SI or 24SI alternators use the BROWN BELT. 

An example of a 21-22SI QSB Alternator
An example of a 21-22SI QSB Alternator

Identifying the Alternator on the QSB 5.9

An example of a 21-22SI QSB Alternator
An example of a 21-22SI QSB Alternator
QSB 24SI Alternator
QSB 24SI Alternator
An example of a 160 Amp 24SI Alternator
An example of a 160 Amp 24SI Alternator
Terminal Identification Pin 1 is Field terminal, pin 2 is a sensing lead
Terminal Identification Pin 1 is Field terminal, pin 2 is a sensing lead
Ground lead location on a QSB 21/22SI Alternator
Ground lead location on a QSB 21/22SI Alternator
Early QSB - 19SI Alternator
Early QSB – 19SI Alternator
QSB - 19SI Alternator
QSB – 19SI Alternator

QSB Alternators