Cummins isl turbo problems. Customer: I have a Cummins ISL 8. 9L engines with a 4" Full Marmon turbo flange. Do you have any suggestions? Failure from excessive exhaust temperatures or hot shutdown of engine results in carbon build-up. Piston rings and cylinder are worn - Replace defective parts. However, these faults are often wrongly attributed to the turbocharger because defects in other compo. Could you provide me with the turbo part number? I also need to verify if the turbo differs from Engine serial # 73395136. Common rail, VGR turbo - no EGR. Incorrect valve timing - Correct or replace timing gear. 9L engines with a 4" Full Marmon CAT turbo flange. 9L ISL (mine is 400HP, 1250 torque, from factory) engine build Dec 16,2006.