Failure of the Alternator on Certain 320D, 321D CR and 323D Excavators{1405} Caterpillar

Excavator:

320D (S/N: DFB1-UP; ZGB1-UP; MDE1-UP; A6F1-UP; A8F1-UP; KGF1-UP; MGG1-UP; FAL1-UP; RBL1-UP; BWP1-UP; BZP1-UP; AMR1-UP; SNS1-UP; PHX1-UP; CXY1-UP; BWZ1-UP; JFZ1-UP; JGZ1-UP)

321D CR (S/N: PBD1-UP; NAS1-UP)

323D (S/N: SDC1-UP; SED1-UP; JLG1-UP; LFL1-UP; BYM1-UP; DKW1-UP)

Introduction

The problem that is identified below has a known solution. Use the solution that is identified below.

Problem

Certain 320D, 321D CR, and 323D Excavators may experience alternator failure. Three failure modes have been identified with the alternator:

• Noise from the alternator

• Battery charge malfunction

• Broken bracket

Possible causes for alternator failure are listed below:

• Belt is out of tension control (the belt is too loose or too tight)

• Alternator mounting bolt or bracket bolt is loose.

• Alternator adjustment bolt is loose

Solution

The belt tension should be checked periodically. When you check or replace a belt, properly adjust the belt tension.

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Illustration 1	g00686313

1. Open the engine hood.

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Illustration 2	g02214693
(1) Bolt (Adjusting) (2) Bolt (Bracket) (3) Alternator (4) Bolt (Mounting)

2. Apply approximately 98 N (22 lb) force midway between the pulleys.

3. Measure the deflection of the belt. The belt should deflect 10 to 12 mm (0.4 to 0.5 inch).

4. If the deflection is not correct, loosen alternator (3) mounting bolt (4) and bracket bolt (2). Turn adjusting bolt (1) in order to adjust the belt tension.

5. When the adjustment is correct, tighten mounting bolt (4) and bracket bolt (2) .

6. Check the deflection of the belt again.

7. If a new belt is installed, run the engine at rated speed for 30 minutes. Check the belt adjustment. Readjust the belt, if necessary.

   Note: Caterpillar recommends checking belt tension every 250 hours or every 1 month, whichever comes first.