7M Engine Hone, Re-Ring, and Valve Seal Rebuild

Engineadvanced✓ OP Confirmed

Problem

7M engine with damaged cylinder walls (rust spots and scratches from improper wire brush use) needing a refresh including new piston rings, valve stem seals, and bearing inspection before reassembly and a manual transmission (W58) swap.

Cylinder wall damage and rust spots from improper wire brush cleaningWorn valve stem sealsScratched thrust washerEngine pulled from 130k mile parts car needing refresh before installation

Root Cause

Normal wear at 130k miles compounded by prior improper cylinder wall cleaning with a wire brush, requiring a hone, new rings, and new valve stem seals before the engine could be reliably installed.

Confidence

High confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted June 2021 on SupraForums.com