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Machining liner counterbores across a 6-cylinder diesel engine block using PT-2000 or PT-2050 cutting tools? Follow this step-by-step professional workshop procedure to set initial cutter depth, position the PT2000-138 spacer tool, resurface counterbore ledges, and transfer the assembly cylinder-to-cylinder without resetting.

Why Re-Measuring Cutter Height Between Cylinders Causes Engine Failure

Heavy-duty diesel engines require strict adherence to cylinder liner protrusion specifications. When machining engine blocks to accept liner shims, every counterbore ledge must be cut to an identical depth relative to the block deck. Technicians who attempt to re-measure and re-zero their cutter bit for each individual cylinder introduce subtle measurement deviations. Variations in ambient shop temperature, microscopic metal dust under dial indicator bases, or slight differences in micrometer feel result in counterbores that vary in depth across the cylinder bank. When the engine is reassembled, a liner seated in a deeper counterbore will sit lower than adjacent liners. When the cylinder head is torqued down, the head gasket cannot clamp properly on the low liner, leading to head gasket failure, coolant leaks, and cylinder misfires. Utilizing the 1-pound PT2000-138 Counterbore Depth Set Spacer Tool completely eliminates these measurement inconsistencies. By locking the depth reference directly into the PT-2000/2050 tool stack, the spacer maintains an unyielding physical stop. Once depth is established on cylinder #1, the entire cutter head can be unbolted, moved to subsequent cylinders, and locked down, cutting every counterbore to the exact same depth in a fraction of the setup time.

The 5-Step Multi-Cylinder Counterbore Depth Setting Protocol

1. Clean Block Deck & Measure Baseline Depth: Remove old liners. Clean the engine block deck face and counterbores thoroughly. Measure counterbore depth around cylinder #1 using a depth micrometer to determine target machining depth.
2. Set Initial Cutter Bit & Insert PT2000-138 Spacer: Mount the PT-2000 or PT-2050 cutter plate over cylinder #1. Insert the PT2000-138 spacer tool into the drive arbor assembly to set the fixed depth stop. Adjust the carbide cutting bit until it contacts the counterbore ledge.
3. Machine Cylinder #1 Counterbore Ledge: Apply cutting fluid to the bit. Turn the drive shaft smoothly while advancing the cutter feed to machine cylinder #1 counterbore ledge flat until all fretting is cleaned away. Lock the cutter arbor height.
4. Transfer Cutter Assembly to Subsequent Cylinders: Unbolt the base plate from cylinder #1. *Do not loosen or adjust the drive arbor or cutter bit depth setting!* Move the entire assembly directly to cylinder #2, bolt the base plate flat to the deck, and machine the counterbore ledge.
5. Repeat Across Bank & Verify Depth Uniformity: Continue transferring the assembly across all remaining cylinders, utilizing the PT2000-138 spacer reference stop to maintain uniform depth. Once all cylinders are machined, clean metal shavings and verify identical depth across all bores using a dial depth gauge before fitting shims.

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