SPRING-VALVE 1757523 - Caterpillar

3408 and 3412 Engines in All ApplicationsA new 5P4185 Fuel Pump Timing Pin is available to be used only on the above engines. Formerly, the 5P4185 Timing Pin was used on 1100 and 3100 Series Engines. On the new pin, the small diameter on the "Zero Rack Set" end of the pin has been removed to prevent possible errors in rack setting. On the earlier pin this small diameter made it possible for the fuel rack to be held in the wrong position as the fuel rack was centered (put at its center position). The result of this condition caused a 0.040" (1.01 mm) error in the rack setting.
5P4185 Fuel Pump Timing Pin in use.Earlier 5P4185 Timing Pins already in use can be changed. Grind off the small diameter on the "Zero Rack Set" end of the pin. If this modification is made to the earlier 5P4185 Timing Pin, it can only be used on 3408 and 3412 Engines. For the 1100 and 3100 Series Engines, use the 8S2291 Fuel Pump Timing Pin.
Early timing pin caused rack setting error.
Timing pin installed in fuel pump housing after modification.