C4.4 Marine Generator Set Caterpillar

Alternator Is Noisy

Usage:

C4.4 NRP

Note: This symptom is not an electronic system fault.

Refer to Systems Operation, Testing and Adjusting for information on possible electrical causes of this condition.

Probable Causes

Alternator drive belt and tensioner
Alternator mounting bracket
Alternator drive pulley
Alternator bearings

Recommended Actions

Note: The procedures have been listed in order of probability. Complete the procedures in order.

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Table 1
Troubleshooting Test Steps	Values	Results
1. Alternator Drive Belt and Tensioner A. Inspect the condition of the alternator drive belt. B. Check the belt tension. If necessary, check the automatic belt tensioner. Note: Excessive belt tension can result in damage to the alternator.	Drive belt	Result: The alternator drive belt is in good condition and the belt tension is correct. Proceed to Test Step 2. Result: The alternator drive belts are not in good condition or the belt tension is incorrect. If the alternator drive belts are worn or damaged, replace the belts. Refer to Disassembly and Assembly for the correct procedure. If necessary, replace the automatic belt tensioner. Refer to Disassembly and Assembly for the correct procedure. Result: The alternator drive belts are in good condition and the belt tension is correct. Proceed to Test Step 2.
2. Alternator Mounting Bracket A. Inspect the alternator mounting bracket for cracks and distortion.	Alternator Mounting Bracket	Result: The alternator mounting bracket is cracked and distorted. Repair the mounting bracket or replace the mounting bracket. Note: The repair/replacement will ensure that the alternator drive belt and the alternator drive pulley are in alignment. Result: The alternator mounting bracket is OK. Proceed to Test Step 3.
3. Alternator Drive Pulley A. Check the condition of the alternator drive pulley. Look for deep grooves that have been worn into the pulley by the belt. Check that the nut for the pulley has not become loose.	Alternator Drive Pulley	Result: There is excessive wear on the alternator drive pulley. Replace the pulley. Result: The alternator drive pulley nut was loose. Tighten the nut. Result: There is not excessive wear on the alternator drive pulley. Proceed to Test Step 4.
4. Alternator Bearings A. Check the alternator bearings for signs of wear.	Alternator bearings	Result: The alternator bearings are not OK. Repair the alternator or replace the alternator, as needed. Refer to Disassembly and Assembly for the correct procedure. Result: The alternator bearings are OK. Contact the Technical Communicator at a Cat dealer.