---

Cylinder Block Inspection and Repair

---

The cylinder block is the foundation of the Cummins ISM, ISMe, and QSM11 engines, supporting the crankshaft, pistons, and main bearings while housing the cooling and lubrication systems . Proper inspection, repair, and machining are crucial to ensure optimal performance, fuel efficiency, and engine longevity .

---

This guide provides step-by-step procedures for cylinder block inspection, measurement techniques, repair procedures, and best practices for servicing the main bearings and crankshaft .

---

For torque values, tolerances, and service specifications , refer to an OEM service manual or consult Diesel Pro Power for expert guidance.

---

Parts Catalog for ISM Cummins Marine and Industrial Engines

Parts Catalog for QSM11 Cummins  Marine and Industrial Engines

---

Safety and Preparation Before Cylinder Block Service

---

Servicing a cylinder block requires attention to detail, precision measurements, and proper handling of heavy components .

---

Personal Protective Equipment (PPE)

---

---

✔ Safety glasses – Protect against debris and metal shavings.
✔ Mechanic gloves – Prevents cuts and chemical exposure.
✔ Steel-toe boots – Protect against heavy falling parts.
✔ Hearing protection – Recommended when using power tools or grinders .

---

Work Area and Tool Preparation

---

• Use a clean and well-lit workspace free from contaminants.
• Ensure all tools and measuring instruments are calibrated properly .
• Use an engine stand or hoist to support the cylinder block securely.
  

  ---

Essential Tools for Cylinder Block Inspection and Repair

---

✔ Dial bore gauge – For measuring cylinder bore wear .
✔ Straightedge and feeler gauges – For deck flatness testing .
✔ Micrometer set – For measuring journal and bearing clearances .
✔ Cylinder honing tool – For reconditioning cylinder bores .
✔ Torque wrench – For proper bolt tightening .

---

Step-by-Step Cylinder Block Inspection and Repair Procedures

---

Step 1: Visual Inspection of the Cylinder Block

---

1. Clean the Cylinder Block Thoroughly
   

   ---

   • Use solvent and compressed air to remove oil, dirt, and debris .
   • Inspect all surfaces for cracks, corrosion, or warping .
     

     ---

2. Check for External Damage
   

   ---

   • Look for cracks around main bearing webs and deck surfaces .
   • Inspect freeze plugs for corrosion or leakage .
     

     ---

3. Inspect the Cooling Passages
   

   ---

   • Ensure coolant ports are free from blockages or scale buildup.
   • Use a borescope or flashlight to check for rust or internal erosion .
     

     ---

Step 2: Measuring Cylinder Bore Wear

---

1. Use a Dial Bore Gauge to Measure Bore Diameter
   

   ---

   • Insert the dial bore gauge into each cylinder bore .
   • Compare measurements to OEM specifications .
     

     ---

2. Check for Out-of-Round and Taper Wear
   

   ---

   • Rotate the gauge 90 degrees to check for bore distortion .
   • If out of round exceeds 0.002 inches (0.05mm), rebore the cylinder .
     

     ---

3. Inspect for Cylinder Liner Wear and Damage
   

   ---

   • Look for scoring, pitting, or uneven wear inside the cylinders.
   • If wear exceeds the recommended limits , the liners must be replaced or honed .
     

     ---

Step 3: Deck Surface Inspection and Flatness Check

---

1. Place a Precision Straightedge Across the Deck
   

   ---

   • Measure gaps with a feeler gauge .
   • Maximum deck warp should not exceed 0.003 inches (0.08mm) .
     

     ---

2. Inspect for Head Gasket Damage
   

   ---

   • Look for uneven wear, erosion, or combustion leaks .
     

     ---

3. Machine the Deck Surface if Necessary
   

   ---

   • If the surface is warped beyond specification , resurface the block.
   • Maintain proper deck height to prevent compression ratio issues.
     

     ---

Step 4: Cylinder Honing and Liner Replacement

---

1. Hone the Cylinders if Bore Wear is Within Tolerance
   

   ---

   • Use a honing tool with medium-grit stones .
   • Apply light machine oil to assist with honing.
     

     ---

2. Replace Cylinder Liners if Needed
   

   ---

   • Remove worn or damaged liners using a liner puller .
   • Install new liners and verify correct protrusion height .
     

     ---

Main Bearing and Crankshaft Service

---

The main bearings and crankshaft are critical components that support engine rotation and power transfer . Proper servicing ensures optimal oil clearance, reduced friction, and longer engine life .

---

Step 1: Inspecting the Main Bearings

---

---

1. Remove the Main Bearing Caps Carefully
   

   ---

   • Loosen bolts in sequence to prevent block stress .
   • Remove bearing caps and keep them in order .
     

     ---

2. Inspect the Bearings for Wear and Damage
   

   ---

   • Look for scoring, pitting, or metal transfer .
   • If bearings show copper exposure , replace them.
     

     ---

3. Measure Bearing Clearance with Plastigage™
   

   ---

   • Place a strip of Plastigage™ on the crankshaft journal .
   • Torque the main cap bolts to spec and measure squash width .
   • Compare results with OEM bearing clearance specifications .
     

     ---

Step 2: Crankshaft Removal and Inspection

---

---

1. Carefully Lift the Crankshaft Using a Hoist
   

   ---

   • Secure the crankshaft with straps to prevent damage.
   • Remove and label bearing shells for reference .
     

     ---

2. Inspect the Crankshaft Journals for Wear
   

   ---

   • Check for scoring, grooves, or heat discoloration .
   • If wear exceeds 0.0015 inches (0.038mm) , the crankshaft must be reground or replaced .
     

     ---

3. Check Crankshaft Runout with a Dial Indicator
   

   ---

   • Mount the crankshaft on V-blocks and measure runout .
   • If runout exceeds OEM limits, replace the crankshaft .
     

     ---

Step 3: Installing New Main Bearings and Reassembling the Crankshaft

---

---

1. Install New Bearings and Apply Lubrication
   

   ---

   • Clean and lubricate bearing surfaces with assembly oil .
   • Install main bearing shells into the block and caps .
     

     ---

2. Lower the Crankshaft into Position
   

   ---

   • Align the crankshaft with the main bearing saddles .
   • Ensure proper fitment without forcing it into place .
     

     ---

3. Torque Main Bearing Bolts in Stages
   

   ---

   • Tighten bolts gradually in a cross-pattern .
   • Use a torque wrench to apply final torque values per OEM specs .
     

     ---

4. Check Crankshaft Rotation
   

   ---

   • Rotate the crankshaft by hand to verify free movement .
   • If resistance is felt, check for misalignment or incorrect bearing fitment .
     

     ---

Final Checks and Reassembly

---

Before reassembling the engine, ensure:

---

✔ All oil passages are clean and free of debris .
✔ Crankshaft end play is within specification .
✔ Main bearing caps are properly torqued and secured .
✔ New seals and gaskets are installed before assembly .

---

Final Notes on Cylinder Block and Crankshaft Service

---

✔ Always use precision measuring tools to verify wear and clearances.
✔ Follow proper torque values and sequences for main bearings.
✔ Maintain cleanliness to prevent contamination in oil and coolant passages .
✔ Consult an OEM service manual or Diesel Pro Power for torque specs and tolerances .

---

By following these best practices for cylinder block service and crankshaft maintenance , you ensure a strong, reliable foundation for the Cummins ISM, ISMe, and QSM11 engines.

---

Parts Catalog for ISM Cummins Marine and Industrial Engines

Parts Catalog for QSM11 Cummins Marine and Industrial Engines

---