When the counterbore depth varies across multiple locations by 0.003 inch, the recommended repair is to...

• A. Hone the block for an oversized liner
• B. Install a tapered shim to even out liner height
• C. Nothing - measurements are acceptable
• D. Machine and shim the counterbore

Answer: (D)

When the counterbore depths aren’t the same across all locations, the liner won’t sit on a perfectly flat plane. The proper fix is to machine the counterbores to a uniform depth and then use shims to bring the liner height to a consistent level relative to the deck. This creates a true, flat seating surface so the head gasket compresses evenly and the head torques down squarely, avoiding leaks or misalignment.

Honing the block for an oversized liner changes the bore diameter rather than addressing the uneven counterbore depth, which isn’t the right remedy for this issue. Installing a tapered shim would produce varying heights and can cause the liner to tilt or sit unevenly, defeating the goal of a flat seating surface. Doing nothing leaves the coplanarity problem unresolved, risking gasket and sealing problems.