When replacing ceramic glow plugs 2017-2019 Cruze; 2018-2019 Equinox, Terrain; 2020-2023 Silverado 1500, Silverado 2500HD/3500HD, Silverado 4500HD/5500HD/6500HD, Tahoe, Suburban, Sierra 1500, Sierra 2500HD/3500HD and Yukon models equipped with the 1.6L diesel engine (RPO LH7), 3.0L diesel engine (RPO LM2, LZ0) or 6.6L diesel engine (RPO L5P, L5D), it is required to use a glow plug hole bore cleaning tool to remove the soot built up on the inside of the glow plug hole. (Fig. 7) The only exception to the glow plug hole cleaning is when servicing a glow plug on the 2.0 L and 2.8 L diesel engines.
Fig. 7
As the engine runs during normal operation, soot builds up between the outside of the glow plug and the inside of the glow plug hole. Once a glow plug is removed, this soot that collected in the bore must be removed. If the soot is not removed before installing a new glow plug, the soot could “side load” the new glow plug and induce a premature failure.
The recommended tool for cleaning the glow plug holes on the 1.6L, 3.0L and 6.6L diesel engines is the EN-52074 Glow Plug Bore Reamer. (Fig. 8)
Fig. 8
With grease applied to the Glow Plug Bore Reamer to catch any carbon removed, it pilots into the glow plug bore and the reamer end passes into the combustion chamber of the head. The hex on Glow Plug Bore Reamer is turned with a ratchet to remove any carbon build up, which remains in the grease on the end of the tool. (Fig. 9)
Fig. 9
Before cleaning the glow plug bore, inspect each removed glow plug to ensure it is fully intact and not broken. If a broken glow plug tip is found, inspect the combustion chamber for the tip or any debris.
After replacing the glow plugs on the 6.6L diesel engine, the glow plug learn procedure should be performed to enable the Glow Plug Control Module to relearn the values of the plugs.
Refer to Bulletin #23-NA-032 for additional information.
– Thanks to Larry Yaw
