Inspecting the Dipstick Tube O-Ring and Lower Oil Pan

When diagnosing engine oil leaks on 2019-2020 Silverado, Sierra; and 2020 CT4-V models equipped with the 2.7L turbocharged 4-cylinder engine (RPO L3B) (Fig. 16), inspect the dipstick tube O-ring and areas above the composite oil pan sealing surface. These potential oil leak areas should be checked before identifying the lower composite oil pan as the source of the engine oil leak.

Fig. 16

Check for an oil leak from the dipstick tube O-ring with an inspection mirror. (Fig. 17)

Fig. 17

Use a black light and tracer dye to identify an oil leak from the composite oil pan sealing surface. (Fig. 18)

TIP: The use of engine oil dye and trace powders are recommended to assit with isolating engine oil leak points. Be sure to clean suspected leak areas thoroughly before using trace powders.

Fig. 18

Lower Oil Pan

The composite oil pan is attached at the engine block lower structural extension (LCE). The oil pan incorporates four jack screws (threaded inserts) that need to be used during the removal procedure. (Fig. 19) Tighten the jack screw by hand 1 to 2 turns. Turn each uniformly and move to the next screw until the oil pan has full separation from the LCE. Do not pry on the oil pan to LCE or the sealing surface may be damaged.

Fig. 19

TIP: Do not gouge or scratch any engine sealing surface during the cleaning process. GM recommends using a plastic razor blade, plastic gasket scraper, a wood scraper or a non-metallic scraper to remove all sealer/gasket material on the surface of engine components that are to be reused. Do not use any other method or technique to remove the sealant or the gasket material from a part.

– Thanks to Robert Halas

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