PULLEY-AUXILIARY 4N6663 - Caterpillar

All Caterpillar Commercial Diesel EnginesBeginning in the first quarter of 1999, all Caterpillar High Efficiency Fuel Filters will include a STAY CLEAN VALVE® on the clean side of the filter. The STAY CLEAN VALVES® will prevent unfiltered fuel, which may contain abrasive contaminants, from entering the clean side of the fuel filter. Unfiltered fuel may cause damage to the engine's fuel system.
Fuel filter prefill practices are harmful to fuel systems, and should always be avoided. Proper fuel filter maintenance requires priming the replacement filter at the time of installation. Many operators and mechanics prefill replacement filters with used fuel from spent filters. This practice allows dirty fuel to bypass the fuel filter media and enter the clean side of the filter. Prefilling a fuel filter compromises the integrity of an engine's fuel system by allowing unfiltered fuel to enter the system and contaminate sensitive fuel injectors and pumps. A priming pump should be used to prime replacement filters with fuel.
IT IS IMPORTANT TO PRIME, AND NOT PREFILL, REPLACEMENT FILTERS IN ORDER TO ENSURE THAT FUEL SYSTEMS RECEIVE FILTERED FUEL ONLY.
With today's higher injection pressures, and closer injector tolerances, clean fuel best delivers maximum engine performance. High efficiency fuel filtration, at 2 microns absolute, has been proven to be essential in preventing fuel system contamination and abrasive injector wear.
As of February 1999, Caterpillar High Efficiency Fuel Filters With STAY CLEAN VALVES® canceled and replaced Caterpillar Standard Fuel Filters. Standard Back-Up Filters are also available, but under restricted conditions. The chart identifies the new and former fuel filters.