PUMP GP-CHARGE 1455291 - Caterpillar

Caterpillar: Confidential Yellow
OPTIONAL:INSTALL IMPROVED PARTS IN AIR INTAKE SHUTOFF ON 3512 MARINE ENGINES (50Y) PI7035 WORLDWIDE
  The information supplied in this service letter may not be valid after the termination date of this program.   Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.
INSTALL IMPROVED PARTS IN AIR INTAKE SHUTOFF ON 3512 MARINE ENGINES (50Y), 1050, 7400, PI7035 U-84 A-77 AU-71 B-35 C-78 E-69 O-66 optional Problem It is possible that excessive wear can occur on several internal parts on the air inlet shutoff on 3512 Marine Engines. This is usually caused by engine vibrations and has caused the shutoff to release the valve, shutting down the engine unexpectedly. The amount of vibration and the extent of wear on the internal parts will determine how often the engine shuts down. (In emergencies the valve will still function automatically.) A stronger release spring is used in place of the former spring, and a spring-type washer has been added on the end of the shaft. See Illustration 1. These two parts minimize vibrations. Other parts have been hardened. A diode has been added to the actuating solenoid to suppress voltage spikes. Affected Engines And Parts Needed All 3512 Marine Engines, 50Y1-50Y519, are included in this Program. Early engines have the 5N2068 Air Intake Shutoff Group, and later engines in this serial number range have the 2W7163 Shutoff Group with some of the new parts. The new parts needed are: 1 - 4W1772 Spring 4 - 2A762 Bolt 1 - 2W8023 Arm 1 - 4W1923 Latch 1 - 5N8961 Pin 1 - 5N8960 Carrier 1 - 9J8606 Washer (Spring) 1 - 6T4751 Solenoid 1 - 1W9070 Diode Assembly 2 - 7N4895 Gasket (Shutoff Hsg.) 1 - 5N3309 Gasket (Shutoff Hsg.) * 5P5700 Seals (Turbocharger) * Replace only if damaged when air lines removed. Action Requested (No Parts Stock Action Needed) This PIP, if done, should be done at the same time as other PIP's on 3512 Marine Engines. Review your PIP records and Service Letters. If there is or has been a problem with the air inlet shutoff, install all the new parts. Modify all affected engines in a multiple engine installation. 1. Remove air inlet shutoff from engine. 2. Partially disassemble the shutoff to the point where all the new parts can be installed. 3. The new, stronger spring is larger in diameter than the former spring. Therefore, enlarge the hole in the housing for the new spring as shown. 4. Install all the listed parts. The added spring washer slips over the small O.D. on the shaft. The washer fits between the shaft shoulder and the cover. 5. Tighten new carrier to 70 +/- 10 N.m (50 +/- 7 lb ft). 6. Remove the former solenoid from the shutoff and install the new solenoid. See Illustration 2. 7. Install the new diode assembly between the two solenoid terminals, and reconnect