An Audible Knock Is Heard on Certain 3500 Dynamic Gas Blending Engines {1278, 1280, 1741} Caterpillar

Electric Power Generation

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

Engine

3512B (S/N: LN41-UP; YBB1-UP; LDE1-UP; LDF1-UP; PTF1-UP; YAM1-UP; 4AW1-UP; 1GZ1-UP)

3512C (S/N: WF31-UP; LN51-UP; WF51-UP; LLA1-UP; LDJ1-UP; RMS1-UP)

3516B (S/N: YAT1-UP)

Petroleum Engine

3512C PETROLEUM (S/N: R1A1-UP; R1S1-UP)

Pumper

SPF343C (S/N: RTX1-UP)

While blending higher BTU levels of field gas, a loud upper end knock is heard at loads between 70% to 80% while substituting with field gas.

Note: This only pertains to 3500 series engines equipped with a Caterpillar Dynamic Gas Blending (DGB) system.

Reduce maximum substitution until the audible knock subsides. This usually will require reducing maximum substitution to 55% to 60%.