Abnormal Engine Tapping Sound

An abnormal engine tapping sound may be heard on some 2019-2022 Silverado and Sierra models equipped with the 2.7L engine (RPO L3B). The sound may be heard from the cam carrier area. Engine misfire DTCs P0300-P030 also may be set.

If a tapping sound is heard from the cam carrier area, it may be the result of excessive movement in the exhaust roller follower, which may be due to axle pin wear. Use a stethoscope to determine if the engine noise can be isolated to the exhaust side of the cam carrier. A worn exhaust roller follower would require the removal of the cam carrier assembly for further inspection. Refer to the appropriate Service Information for cam carrier removal.

Once the cam carrier is removed, inspect each of the exhaust roller followers for increased wear or up/down movement in the roller. (Fig. 6)

Fig. 6

Excessive up/down movement is an indication of increased axle pin wear and, in worst cases, the rollers may come out of position, leading to a bent valve or damaged valve stem. (Fig. 7)

Fig. 7

TIP: Inspect the cylinder head area for any loose roller bearings and remove before reassembly. Each of the roller followers will have a total of 10 roller bearings.

If a worn exhaust roller follower is found, replace all eight of the exhaust hydraulic lash adjusters and exhaust followers. The exhaust camshaft also should be inspected for damage or premature wear caused by a worn roller follower. (Fig. 8)

Fig. 8

For more information, refer to #PIP5847.

– Thanks to Robert Halas

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