Check for the Correct Bolt Torque for the Air Shutoff Butterfly Plate on Certain 3500 Engines {1078} Caterpillar

Gen Set Engine

3508B (S/N: 6PN1-UP)

3512B (S/N: 8RM1-UP; 4AW1-UP)

3516 (S/N: 25Z1-UP)

3516B (S/N: 7RN1-UP; 2JW1-UP)

Generator Set

3512B (S/N: CMC1-UP; LDF1-UP; PTM1-UP; YAM1-UP)

3512B GENSET (S/N: ZAH1-UP)

3516 (S/N: ZAL1-UP; ZBL1-UP; GZR1-UP; YAS1-UP; YBS1-UP)

3516B (S/N: ZBP1-UP; GAR1-UP; PBR1-UP; ZAR1-UP; ZBR1-UP; GZS1-UP; YAT1-UP; YBT1-UP; YAW1-UP; YBW1-UP)

3516B GEN SET (S/N: ZAP1-UP)

Petroleum Engine

3512C (S/N: R1T1-UP)

3512C PETROLEUM (S/N: R1S1-UP)

Petroleum Powertrain Package

TH55-E70-3512CP (S/N: PNY1-UP)

The bolts that retain the butterfly plate in the air shutoffs (ASOs) were not consistently torqued.

The ASO part numbers are listed in Table 1.

1. Gain access to the ASOs by removing both the left-hand and the right-hand air filters

2. Check the bolt torque.

   Torque 3/8" bolt ... 47 N·m (35 lb ft)

   Torque 1/4" bolt ... 12 N·m (9 lb ft)

3. Test the ASOs according to the Operation and Maintenance Manual after the rework to ensure proper function of the valve.

This change is effective for the serial numbers listed in Table 2.