Chasing a repeating head gasket blowout on a Caterpillar C15 or a Detroit Series 60? The real issue isn't the gasket seal. The M50133 Upper Deck Counterbore Tool delivers the precise machining accuracy needed to permanently eliminate liner drop.

The High Stakes of Counterbore Fretting

On high-horsepower diesel engines, the block counterbore ledge suffers relentless mechanical punishment. Over hundreds of thousands of miles, the microscopic shifting of the cylinder liner flange erodes the cast iron block deck—a process known as fretting. Once this ledge drops or pits, the cylinder liner sinks, destroying uniform head gasket crush and causing localized stress cracks along the liner flange. Slipping a fresh shim onto a pitted, out-of-round ledge is a temporary band-aid that guarantees a costly shop comeback. The M50133 counterbore system mounts securely to the block deck, forcing the precision-guided cutting tip to re-face the damaged ledge perfectly flat and concentric to the cylinder bore axis.

• Universal Multi-Platform Modular Housing – Accepts interchangeable cutter plates to seamlessly service Cummins 855/N-14, Caterpillar 3406/C15, Detroit Series 60, and Navistar DT466 blocks.
• Direct Legacy Tool Replacement – Replaces classic factory standards including the Kent-Moore Porta-Tool **PT-2250-B**, **PT2250**, and **PT2200** chassis.
• Self-Centering Machining Path – Locks flawlessly onto the cylinder bore centerline, completely eliminating operator deviation and angled cuts.
• In-Frame Repair Efficiency – Allows field mechanics to restore original factory deck geometries in-frame without stripping down and hauling the block to a machine shop.
• Industrial Cast Iron Mass – A substantial 56.00 lbs specialized shop casting built to eliminate tool chatter and produce clean finishes under high cutting resistance.

Fix the Structural Root Cause

The M50133 Upper Deck Counterbore Tool is a vital infrastructure investment for high-volume diesel machine shops, commercial truck fleets, and heavy equipment rebuilding bays. Stop risking your shop's reputation on un-machined block surfaces—verify your liner protrusion heights with absolute machining authority.

---