How to disassemble the Cummins M11 series engine, including the pistons and connecting rods.

 Rotate the crankshaft to expose the carbon deposits above the piston inside the cylinder liner. Remove the carbon deposits using a fine-fiber abrasive pad (such as Scotch-Brite 7448, part number 3823258 or equivalent) and solvent, as shown in Figure 2-125.

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 Figure 2-122 Removing the gear chamber housing

 ② Use a crankshaft turning tool to rotate the crankshaft and fix the connecting rod at the bottom dead center (BDC) position so that the connecting rod bolts can be removed and loosened, as shown in Figure 2-126.

 

 

 Figure 2-123 Install the crankshaft turning tool onto the flywheel end of the crankshaft.

 

 

 Figure 2-124 Remove the cooling nozzle

 

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 Figure 2-125 Removing carbon buildup from the upper inner surface of the piston

 

 

 Figure 2-126. Rotate the crankshaft to fix the connecting rod at the bottom dead center position, then loosen the connecting rod bolts.

 ③ Use a hammer to tap the connecting rod bolt head to loosen the connecting rod cap from the annular locating pin. Remove the connecting rod bolt and connecting rod cap, see Figure 2-127. ④ Mark the cylinder number and the letter "L" on the surface of the lower bearing locating tongue, see Figure 2-128. However, it is strictly forbidden to make marks on the mating surface between the bearing and the crankshaft, to avoid damaging the crankshaft if the bearing continues to be used.

 

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Figure 2-127 Gently tap the connecting rod bolt head to loosen the connecting rod cap, then remove the connecting rod cap and bolt.

 

 Figure 2-128 Marking on the lower bearing locating tongue.

 

 Install the connecting rod guide pin (part number 3376038) in the connecting rod bolt hole. Use a wooden dowel and a hammer to push the connecting rod away from the crankshaft, as shown in Figure 2-129. Continue pushing the connecting rod until the piston rings protrude from the cylinder block.

 

6. Remove the piston and connecting rod assembly and mark it, as shown in Figure 2-130. If the removed piston and connecting rod assembly is still usable, it must be reassembled with the original cylinder number. 

7Place the piston and connecting rod assembly on a special test bench to prevent damage, as shown in Figure 2-131. 

 8. Mark the connecting rod and its mating connecting rod cap with special markings, as shown in Figure 2-132. During assembly, the markings on the connecting rod and connecting rod cap must match and be on the same side of the engine. 

 9. Remove the upper connecting rod bearing and mark the cylinder number and the letter "u" on the flat surface of the locating tongue, as shown in Figure 2-133.

 

 

 Figure 2-129. Install the guide pin in the connecting rod bolt hole, and use a hammer to push the connecting rod away from the crankshaft.

 

Figure 2-130 Remove the piston connecting rod assembly and mark it.

 

 Figure 2-131 Placing the piston and connecting rod assembly on a special test bench.

 

 Figure 2-132 Special markings are made on each pair of connecting rods and connecting rod caps.