3412 INDUSTRIAL & MARINE ENGINES Caterpillar


Pistons

Usage:

Remove Pistons

Start By:

a. remove cylinder head assemblies

b. remove oil pump

c. remove piston cooling tubes


NOTICE

If the piston cooling tubes are not removed, it is possible for the connecting rod to hit the piston cooling tubes. This can move the piston cooling tube out of alignment. A piston cooling tube that is not in alignment will not direct the lubricant to the correct location. The result can be piston seizure.


1. Remove the carbon from the top inside surface of the cylinder liners.

2. Turn the crankshaft with Tool (A) until two pistons are at bottom center.

3. Remove bearing 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 up until the piston rings are clear of the cylinder liner. Remove pistons (2).

NOTE: Keep each cap with the respective connecting rod.


NOTICE

Do not turn the crankshaft while any of the connecting rods are in the engine without the caps installed. Do not damage the cooling tubes when the pistons are removed.


5. Do steps 1 through 4 for the remainder of the pistons.

Install Pistons

1. Put clean engine oil on the piston rings, connecting rod bearings and cylinder liners.

2. Put two pistons in position opposite of each other in the correct bore of the block. Install pistons (1) with tool (A).


NOTICE

Be sure that the pistons are installed with flat surfaces (2) of the connecting rod toward each other and the chamfered sides (4) toward the crankshaft.


NOTE: For more detail about checking bearing clearances and installation of connecting rod bearings, see Remove & Install Connecting Rod Bearings.

3. Check the bearing clearances with Plastigage.

4. Put 2P2506 Thread Lubricant on bolts (5). Install caps (3) and nuts finger tight. Tighten each nut to a torque of 80 ± 8 N·m (60 ± 6 lb ft). Put a mark across the nut and bolts. Tighten each nut 120° more.


NOTICE

Do not use an impact wrench to tighten the nuts the additional 120° more.


5. Check the side clearance between two connecting rods on the same crankshaft journal. Clearance must be 0.28 to 0.84 mm (.011 to .033 in) for new rods.

6. Do Steps 1 thru 5 for the remainder of the pistons.

End By:

a. install piston cooling tubes

b. install oil pump

c. install cylinder head assemblies

Disassemble & Assemble Pistons (Earlier - Rod Pin Bearing With Straight Sides)

Start By:

a. remove pistons

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

2. Remove retainer ring (1) with Tool (C).

3. Remove pin (2) and the connecting rod (4) from the piston (3).

4. Remove the piston rings from the piston with Tool (A). Clean the piston ring grooves on the pistons with an acceptable ring groove cleaning rod.

NOTE: See Use of Pistons Pin Bearing Removal & Installation Tools, Special Instruction, Form No. SMHS7295.

5. Heat the connecting rod in an oven to a temperature of 177° to 260°C (350 to 500°F). Never use a direct flame to heat a connecting rod.

6. Put connecting rod (4) in position on the base plate of Tool (B). Put a new rod pin bearing (5) on the adapter part of Tool (B). Make sure that the joint in the rod pin bearing is 90 ± 10° from a center line through the crankshaft and pin bearing bores.

7. Install the pusher adapter (7) and pusher (8), part of Tool (B), on the adapter.

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

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

9. Use a pin boring machine to make the rod pin bearing the correct size. The bore in the new rod pin bearing must be 50.830 ± 0.008 mm (2.0012 ± .0003 in).

10. Check the clearance between the ends of piston rings. See Pistons & Ring in specifications.

NOTE: The following steps are for the assembly of the pistons.

11. Install the oil ring spring in the oil ring groove of the piston.

NOTE: The oil ring is to be installed over the spring with the oil ring end gap of 180° from the oil ring spring joint.

12. Install the oil ring on the piston with Tool (A).

13. Install the second (intermediate) piston ring with the side that has the identification "UP-2" toward the top of the piston with Tool (A).

14. Install the first (top) piston ring with the side that has the identification "UP-1" toward the top of the piston with Tool (A).

NOTE: After the installation of all three piston rings, put the piston rings in position so the end gaps are 120° apart.

15. Put piston (3) in position on connecting rod (4). Put clean engine oil on pin (2) and install the pin. Install retainer rings (1) with Tool (C). Make sure the retainer rings are in grooves of the piston.

16. Install the bearings in the connecting rod and connecting rod cap.

End By:

a. install pistons

Disassemble & Assemble Pistons (Later - Tapered Rod Pin Bearings)

Start By:

a. remove pistons

1. Remove bearings (3) from the connecting rod and connecting rod cap.

2. Remove retainer ring (1) with Tool (A).

3. Remove pin (2) and connecting rod (4) from the piston.

4. Remove piston ring (5) from the piston with Tool (B). Clean the piston ring grooves on the pistons on the pistons with an acceptable ring groove cleaning tool.

NOTE: See Use of Piston Pin Bearing Removal & Installation Tools, Special Instructions, Form No. SMHS7295.

5. Heat the connecting rod (4) in an oven to a temperature of 177° to 260° C (350° to 500°F). Never use a direct flame to heat a connecting rod.

6. Put connecting rod (4) in position on the base plate of Tool (C). Put a new rod pin bearing (6) on the adapter part of Tool (C).

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

7. Use Tool (C) to push the new bearing into the connecting rod until the push adapter of Tool (C) makes full contact with the connecting rod surface.

8. Use a pin boring machine to make the rod pin bearing the correct size. The bore in the new rod pin bearing must be 50.830 ± 0.008 mm (2.0012 ± .0003 in).

9. Check the clearance between the ends of the piston rings. See Pistons & Rings in Specifications.

NOTE: The following steps are for the assembly of the pistons.

10. Install the oil ring spring in the oil ring groove of the piston.

NOTE: The oil ring is to be installed over the spring with the oil ring end gap 180° from the oil ring spring joint.

11. Install the oil ring on the piston with tool (B).

12. Install the second (intermediate) piston ring with the side that has the identification "UP-2" toward the top of the piston with Tool (B).

13. Install the first (top) piston ring with the side that has the identification "UP-1" toward the top of the piston with Tool (B).

NOTE: After the installation of all three piston rings, put the piston rings in position so the end gaps are 120° apart.

14. Put the piston in position on connecting rod (4). Put clean engine oil pin (2) and install the pin. Install retainer ring (1) with Tool (A). Make sure the retainer rings are in the grooves of the pistons.

15. Install bearings (3) in the connecting rod and connecting rod cap.

End By:

a. install pistons

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