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Engine - Rocker Arm Ticking Noise at Idle Speed

90mitsubishi09
SUBJECT: V6 ENGINE TICKING NOISE AT IDLE
NO. TSB-90-11-006

DATE August, 1990

MODEL All Early 1990 V6
PURPOSE

Some early 1990 V6 engines may emit a ticking noise at idle (either continuously, intermittently, cold, or hot). This ticking noise may originate from the rocker arm areas of the engine. A small casting burr on the side face of the rocker arm may not allow the rocker arm to fully contact the side bearing surface of the bearing cap. This condition may be experienced on engines manufactured before December 1989 with engine numbers lower than # LS7449. This bulletin provides burr removal procedures for engines that have a ticking noise at idle coming from the rocker arm areas.


WARRANTY INFORMATION

Standard warranty procedures apply.

REPAIR PROCEDURES

Determine which bank the noise is coming from.

Remove the rocker arm assembly as described in the appropriate service manual.

Remove the rocker arms from the rocker arm shafts, noting the arm and bearing cap positions for later reassembly. Clean the rocker arms.

Figure 1:




ROCKER ARM INSPECTION

Inspect each rocker arm for complete face contact (Figure 1). Rocker arms with complete face contact do not require burr removal.

Figure 2:




Rocker arms that do not have complete face contact have line contact along the inside diameter of the hole (Figure 2) require casting burr removal.

Figure 3:




CASTING BURR REMOVAL

Using a hard, smooth oil stone remove the casting burr from the rocker arm side face (Figure 3).

CAUTION: Do not use a file to remove the casting burr. The oil stone must be in near new condition (smooth and no gouges).


REASSEMBLY

Thoroughly clean the rocker arm.

Reassemble the rocker arm assembly.

Reinstall the assembly on the engine as described in the service manual.