LS-8240 / PT-8240 Caterpillar 3406 / C15 Block Deck / Upper Counterbore Insert

The LS-8240 (also referenced as PT-8240, 5P4173) is a precision block insert designed specifically forCaterpillar 3406 C15 engine blocks. This upper deck insert fills and restores the upper counterbore (shim ledge) area of the block to factory dimensions, providing a stable, concentric surface for correct liner protrusion and sealing.The external diameter of this insert is 6.665″ with a height of 0.205″.

In cases where the deck surface or upper ledge has been Pitted, Worn, or Cracked, the LS-8240 insert allows rebuilders to restore the proper counterbore without excessive material removal. It press-fits into the prepared counterbore and provides a durable, corrosion-resistant surface ideal for long-term engine performance.

Key Features & Benefits

• Engineered specifically for Cat 3406 engine blocks

• OD 6.665″, Height 0.205″ — matches OEM block insert dimensions

• Restores upper deck shim ledge / counterbore to precise spec

• Helps preserve liner protrusion and sealing integrity

• Made of high-quality material suitable for engine rebuild environments

Typical Applications

• Rebuilding / restoring Caterpillar 3406 blocks after machining or damage

• Correcting misaligned or worn upper deck surfaces

• Preparing engine blocks for liner installation with accurate shim alignment

• Use in heavy-duty repair shops, diesel rebuild centers, and fleet engine shops