Cummins N14 STC, Celect, Celect Plus – Service Manual Engine Noise Excessive – Piston

Symptom Tree  t051

This is symptom tree
Cause Correction

Refer to Engine Noise Diagnostic Procedures – General Information within troubleshooting overview procedure at the end of Section TS before using this symptom tree.

Fuel grade is not correct for the application or the fuel quality is poor

Operate the engine from a tank of known high quality fuel. Refer to Fuels for Cummins® Engines, Bulletin 3379001.


Overhead adjustments are not correct

Measure and adjust the overhead settings. Refer to Procedure 003-004 in Section 3.


Injector(s) are malfunctioning

Perform diagnostics to find the damaged injector(s). Replace the injector(s) as necessary. Refer to Procedure 006-026 in Section 6.


Carbon deposits on the top of the pistons are contacting the cylinder head

Remove the cylinder head and check for carbon deposits on the pistons. If deposits are excessive, remove and clean the pistons. Check the piston rings for damage or wear. Refer to Procedure 002-004 in Section 2, Procedure 001-054, Procedure 001-043, and Procedure 001-047 in Section 1.


Piston pin or bushing is loose, worn, or not installed correctly

Remove the pistons and inspect the piston pins and bushings for damage, wear, and correct installation. Refer to Procedure 001-043 in Section 1.


Piston, piston rings, or cylinder liner is worn or damaged

Inspect the air intake system for leaks. Refer to Procedure 001-043, Procedure 001-047, and Procedure 001-028 in Section 1.


Connecting rod is bent or out of alignment

Remove and inspect the connecting rods. Refer to Procedure 001-014 in Section 1.

Last Modified:  22-Dec-2011