Although, the N54 engine has an all aluminum crankcase, many of the bolts are still aluminum as on the N52.
This is to reduce any potential confusion between steel and aluminum bolts. Some bolts, for example, are steel such as the cylinder head cover bolts. This is possible, due to the plastic cylinder head cover.
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Fig. 11: Identifying Bolt
The N52KP and N51 engines use the same aluminum bolt configuration as the N52 engine, with little change.
The cylinder head cover bolts are like the N54 - steel, due to the plastic cylinder head cover.
The same rules apply to the handling of aluminum bolts as in the past.
Strict adherence to repair instructions is required to ensure proper connections.
Be sure to follow the proper torque/tightening angle sequence as outlined in the "tightening torques" section of TIS.
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Fig. 12: Identifying Aluminum Bolt
Cylinder Head Cover
Valvetrain
Gaskets And Seals
Removing And Installing/Replacing Thigh Support Holder On Front Left Or
Right Seat (Sports/Electric)
Overhauling Left Or Right Rear Brake Caliper (Brake Caliper Removed)