Cummins ISX11.9 CM2250 – Service Manual 001-999   Cylinder Block – Overview

General Information

The cylinder block is an inline 6 cylinder with camshaft in block design made of grey cast iron.  The ISX11.9 cylinder block is designed to accommodate a rear gear train. The block stiffener plate is a required component for all engines. The front lubricating oil transfer cover should not be removed except to wash the internal passages of the cylinder block.  Removing this cover can expose the oil system to possible contamination.		SMALL | MEDIUM | LARGE
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The ISX11.9 connecting rod crankshaft bore is an angle and fracture split design with four capscrews. The connecting rod I-beam is drilled to provide oil to the piston pin. The long side of the connecting rod shank installs on the left side of  the engine, or with the rotation of the crankshaft.		SMALL | MEDIUM | LARGE
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The cylinder liners are of a mid-stop cylinder liner design and are induction hardened.		SMALL | MEDIUM | LARGE
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The ISX11.9 engine uses single-piece steel pistons with target piston cooling nozzles.		SMALL | MEDIUM | LARGE
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The ISX11.9 vibration damper incorporates the crankshaft pulley on the damper. The damper also offers a ¾-inch square drive front barring location.		SMALL | MEDIUM | LARGE
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The ISX11.9 front gear train uses the following components: Camshaft gear Idler gear Air compressor gear.		SMALL | MEDIUM | LARGE
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The ISX11.9 rear gear train uses the following components: Camshaft gear Fuel pump gear Lubricating oil pump idler gear Idler gear (compound) Crankshaft gear Lubricating oil pump gear.		SMALL | MEDIUM | LARGE
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Main Bearing Cap Fretting:

Fretting is micro-motion between the main bearing cap and cylinder block that results in material loss at the joint. This motion causes a loss of crankshaft to main bearing running clearance that can lead to a spun main bearing, a spun connecting rod bearing, and/or a broken crankshaft.

There is risk when overhauling or replacing the main bearings in a cylinder block that has incurred main bearing cap fretting. Inserting new standard main bearing shells into a joint that has sustained sufficient loss of material can lead to zero crankshaft/bearing clearance. This can cause the crankshaft to lock in place.

Plastigage™ provides a fast and accurate method to check bearing clearances. Plastigage™ is a special extruded plastic thread of a definite diameter with accurately controlled crush properties. Plastigage™ is packaged in calibrated envelopes, 12 envelopes per box. These envelopes not only protect the plastic threads, but also serve directly as scales to measure the bearing clearance. Both sides of the envelope have a printed scale of graduations. One side is calibrated in inches, the other in millimeters. The numbers on the scale are the bearing clearances in thousandths of an inch or millimeter. When the width of a compressed section of Plastigage™ in a bearing or journal is compared with the appropriate-numbered graduation, the bearing clearance can be read directly from the scale.

Plastigage™ is available from a local parts store in four styles to cover different clearance ranges. Both Plastigage™ thread and its matching envelope have a distinctive color for each clearance range.