Operation and maintenance manual

Troubleshooting Symptoms Charts QSB4.5 and QSB6.7
Page TS-38 Section TS - Troubleshooting Symptoms
Engine Vibration Excessive
Cause Correction
STEP 1
Belt-driven accessories are malfunctioning
.............
Check the fan hub, alternator, refrigerant
compressor, and hydraulic pump for interference.
Isolate belt-driven accessories and check for
vibration. Refer to Section 3 and Section 4.
OK
Go To Next Step
STEP 2
Air compressor pumping time is excessive
.............
Refer to the Air Compressor Cycles Frequently
symptom tree.
OK
Go To Next Step
STEP 3
Engine idle speed is set too low (electronically
controlled fuel systems)
.............
Verify the correct idle speed setting. Increase the
idle speed with the idle increment switch or an
electronic service tool. Refer to Section 1.
OK
Go To Next Step
STEP 4
Engine mounts are worn, damaged, or not correct
.............
Check the engine mounts. Refer to the OEM
service manual.
OK
Go To Next Step
STEP 5
Fan is loose, damaged, or has excessive hub
bearing end play
............. Check the fan. Refer to Section 3.
OK
Go To Next Step
STEP 6
Engine is misfiring
.............
Refer to the Engine Runs Rough or Misfires
symptom tree.
OK
Go To Next Step
STEP 7
Electronic fault codes are active
.............
For instructions on how to read active fault codes,
refer to Section 1. If fault codes are active, contact
a Cummins Authorized Repair Facility.
OK
Go To Next Step
STEP 8
Vibration damper is damaged
............. Inspect the vibration damper. Refer to Section 7.
OK
Go To Next Step
STEP 9
Alternator bearing worn or damaged
.............
Clean and replace the alternator. Refer to the
OEM service manual.
OK
Go To Next Step
STEP 10
Contact a Cummins® Authorized Repair Facility