3208 INDUSTRIAL ENGINE ATTACHMENTS – Pistons & Connecting Rod Assemblies

Remove Pistons & Connecting Rod Assemblies

Start By:

a. remove cylinder head assemblies

b. remove oil pan

1. Remove the carbon from the top inside surface of the cylinders with Tool (A).

2. Turn the crankshaft until two pistons are at bottom center.

3. Remove connecting rod caps (1) from the two connecting rods. Put pieces of rubber hose or tape on the threads of the connecting rod bolts as protection for the crankshaft.

4. Push the pistons and connecting rods away from the crankshaft until the piston rings are above the cylinder block.

5. Remove the two piston assemblies (2) and the connecting rods. Keep each connecting rod cap with its respective connecting rod and piston. Put identification marks on each connecting rod as to its location for use at installation.


Do not turn the crankshaft while any of the connecting rods are in the engine without the caps installed.

6. Do Steps 2 through 5 for the remainder of the pistons.

Install Pistons & Connecting Rod Assemblies

1. Put clean engine oil on the piston rings, connecting rod bearings, cylinder walls and crankshaft bearing journals.

2. Turn the crankshaft until the bearing journal of the pistons to be installed is at bottom center.

3. Make sure the piston ring gaps are at least 120 degreesapart on the piston.

4. Use Tool (A), and install the piston in position on the same cylinder bore from which it was removed. The hole (crater) in the top of the piston must be toward (nearest) the center of the engine.

NOTE: For more detail about the installation of connecting rod bearings, see the topic “Remove & Install Connecting Rod Bearings”.

5. Check the bearing clearances with Tool (B).

6. Put Clean Engine Oilon the threads of the bolts and contact surfaces of the nuts for the connecting rod caps.


When the connecting rod caps are installed, make sure that the number on the side of the cap is next to and respective with the number on the side of the connecting rod.

7. Put the cap (1) in position on the connecting rod, and install the nuts. Tighten the nuts to a torque of 40 ± 4 N·m (30 ± 3 lb ft). Put a mark on each nut and the end of each bolt. Tighten the nuts 60 ± 5 degrees(1/6 turn) more.

8. Check the side clearance between the connecting rods on the same crankshaft journal. Clearance must be 0.08 to 0.84 mm (.003 to .033 in)for new rods.

9. Do Steps 1 through 8 for the remainder of the pistons.

End By:

a. install oil pan

b. install cylinder head assemblies

Disassemble Pistons & Connecting Rod Assemblies

Start By:

a. remove pistons and connecting rod assemblies

1. Remove the rings from the piston with Tool (A).

2. Remove the bearings from the connecting rod and connecting rod cap.

3. Remove snap rings (2), pin (1) and connecting rod (3) from the piston.

4. See Use Of Piston Pin Bearing Removal & Installation Tools, Special Instructions, SMHS7295, for more information on removal and installation of piston pin bearings.

5. Heat the connecting rod to a temperature of 176 to 260°C (350 to 500°F). Put 5P-8654 Spacer(11) in the base plate. Put the connecting rod on the base plate of Tooling (B).

6. Put the connecting rod piston pin bearing end in the center of the port assembly of Tooling (B). Install pin (7) in the center of the bore for the connecting rod bearings.

7. Install 5P-9653 Adapter(9). Put the hole in the adapter in alignment with the hole in the base plate of Tooling (B).

8. Install clamp bar (10) and clamp pin (6).

9. Install new piston pin bearing (5) on adapter (9).

NOTE: The old bearing is pushed out by Tooling (B) as the new bearing is installed.

10. Put 5P-8645 Adapter(8) in position as shown with the taper side down. The piston pin bearing joint must be in alignment with the hole in adapter (9) and the base plate of Tooling (B).

11. Put pusher (4) on adapter (8).

12. Use Tooling (B) to push the new piston pin bearing into the connecting rod until adapter (8) of Tooling (B) makes full contact with the connecting rod surface.

13. Remove the connecting rod and the old piston pin bearing from Tooling (B).

14. Check the piston pin bearing bore diameter after the bearing is installed. The correct dimension is 38.125 ± 0.008 mm (1.5010 ± .0003 in).

Assemble Pistons & Connecting Rod Assemblies

1. Install connecting rod (1) in the piston with the boss on the small end of connecting rod on the same side as the hole (crater) in top of the piston.

2. Install piston pin (2) and snap ring (3).

3. When old pistons are to be used, clean the piston grooves with a suitable piston ring groove cleaner [Tool (A)].

4. Install the spring for the oil ring. Install the oil ring with Tool (B). The gap in the ring must be approximately 180 degreesfrom the oil ring spring connections.

5. Install the compression ring with Tool (B). The side of the ring that has the identification “TOP” must be toward the top of the piston. The gaps in the rings must be approximately 120 degreesapart.

NOTE: Compression rings that do not have identification marks must be installed with the edge that has the bevel toward the top edge that has the bevel toward the top of the piston.

6. Install the connecting rod bearings.

End By:

a. install pistons and connecting rod assemblies