3500 GENERATOR SET ENGINES Caterpillar

Start By:

a. remove rocker shaft assemblies and push rods

b. remove front drive housing

c. remove front balancer group (3508 only)

d. remove rear gear group (Step 1 only)

e. remove piston cooling jets

1. Put the engine in the position shown. The weight of the 3508 engine is approximately 4445 kg (9800 lb). The weight of the 3512 engine is approximately 5902 kg (13,000 lb). The weight of the 3516 engine is approximately 7718 kg (17,000 lb).

NOTE: The counterweights do not have to be removed from the crankshaft if the piston and connecting rod assemblies have been removed from the engine.

2. Put identification marks on counterweights (1), and remove them from the crankshaft.

3. Remove bearing caps (2) from the connecting rod, and push the connecting rods away from the crankshaft. Use wire to hold the upper half of the connecting rods away from the crankshaft.

4. Remove the center main bearing cap, and remove two thrust plates (3) from each side of the main bearing.

Typical Example

5. Use two of the bolts that hold the flywheel to the crankshaft, and install a bolt in each end of the crankshaft. Fasten a hoist to the crankshaft as shown.

6. Remove the remainder of main bearing caps (5), and remove crankshaft (4) from the cylinder block. The weight of the crankshaft is approximately 363 kg (799 lb) for a 3508, 545 kg (1199 lb) for a 3512, and 726 kg (1597 lb) for a 3516.

7. Remove the upper halves of the bearings from the cylinder block and the connecting rod assemblies.

8. If necessary, remove bolts (7) to remove gears (6) from each end of the crankshaft.

Install Crankshaft

1. If gears (6) were removed from the crankshaft, install the gears on each end of crankshaft (4).

NOTE: The upper halves of the main bearings have an oil hole in the center of the bearing.

2. Install the upper halves of main bearings (8) in the block.

3. Put the upper halves of rod bearings (9) in position in the connecting rod assemblies

NOTE: Install the bearings dry when clearance check are made. Put clean engine oil on the bearings for final assembly.

NOTE: If the crankshaft journals and bores for the block and rods were measured at disassembly and found to be within specifications, no further checks are necessary. However, if the serviceman still wants to measure the bearing clearances, Plastigage is recommended. Lead wire, shim stock or use of a dial bore gauge can damage the bearing surface.

NOTE: The serviceman must be very careful to use Plastigage correctly. The following points must be remembered:

- Make sure that the back of the bearings and the bores are clean and dry.

- Make sure that the bearing locking tabs are properly seated in their slots.

- The crankshaft must be free of oil where the Plastigage touches it.

- If the main bearing clearances are checked with the engine upright or on its side, the crankshaft must be supported. Use a jack under an adjacent crankshaft counterweight and hold the crankshaft against the crown of the bearing. If the crankshaft is not supported, the weight of the crankshaft will cause incorrect readings.

Put a piece of Plastigage on the crown of the bearing half that is in the cap. Do not allow the Plastigage to extend over the edge of the bearing.

- Install the bearing cap using the correct torque-turn specifications. Do not use an impact wrench. Be careful not to dislodge the bearing when the cap is installed.

- Do not turn the crankshaft with the Plastigage installed.

- Carefully remove the cap but do not remove the Plastigage. Measure the width of the Plastigage while it is in the bearing cap or on the crankshaft journal. Do this by using the correct scale on the package. Record the measurements.

- Remove the Plastigage before reinstalling the cap.

When using Plastigage, the reading can sometimes be unclear. For example, all parts of the Plastigage are not the same width. Measure the major widths to make sure that they are within the specification range. Also, experience has shown that when checking clearances tighter than 0.10 mm (.004"), the readings may be low by 0.013 to 0.025 mm (.0005 to .0010"). Out-of-round journals can give faulty readings. Also, journal taper may be indicated when one end of the Plastigage is wider that the other.

For complete details concerning measuring bearing clearances, see Engine Bearings And Crankshafts, Form No SEBD0531.

Typical Example

NOTE: Make sure the word "FRONT" on the end of the crankshaft is toward the front of the cylinder block when the crankshaft is installed.

4. Fasten a hoist to crankshaft (4) with two flywheel bolts. Put the crankshaft in the cylinder block.

5. If necessary, check the main bearing clearances with Plastigage as follows:

a. Put the main bearings in position in the main bearing caps. Make sure tab on the back of the bearing is in position in the tab groove in the main bearing cap.

b. Put a piece of Plastigage in position on the crown of the crankshaft.

NOTE: The main bearing caps must be installed with the word "FRONT" and the cast part number toward the front of the cylinder block. Each cap has a number on the bottom surface and must be installed in the same position as the correct number on the side of the block pan rail.

c. Put Fel-pro C100 Lubricant (if not available, use 2P2506 Thread Lubricant) on the main bearing cap bolts and tighten them in number sequence shown to a torque of 136 ± 14 N·m (100 ± 10 lb ft). Then tighten the bolts in the number sequence shown 210 ± 5° more.

NOTE: Do not turn the crankshaft when the Plastigage is in position.

d. Remove the caps and measure the Plastigage. The main bearing clearance must be 0.122 to 0.241 mm (.0048 to .0095 in).

6. Put clean engine oil on thrust plates (3). Install thrust plates (3) on each side of the center main bearing.

7. Put the main bearing caps in position, and tighten the bolts as in Step 5c.

8. Check the crankshaft end play with tool (A). The end play must be 0.17 to 0.63 mm (.007 to .025 in).

9. Remove the wire that holds the upper half of the connecting rods in place. Pull the connecting rod and piston assemblies into position against the crankshaft.

NOTE: Install the connecting rod bearings dry when clearance checks are made. Put clean engine oil on the connecting rod bearings for final assembly.

10. Install the lower half of rod bearing (10) with the tab in the back of the bearing in the tab groove of the connecting rod cap.

11. If necessary, check the rod bearing clearances with Plastigage as follows:

a. Put a piece of Plastigage on the crown of the crankshaft.

NOTE: The connecting rod caps must be installed with the number on the side of the cap next to and respective with the number on the side of the connecting rod.

NOTE: Bolts (11) and (12) are installed on the same side of the rod cap that has the locating pin. The locating pin must extend 4.0 ± 0.5 mm (.16 ± .02 in) from the rod cap.

b. Put Fel-pro C100 Lubricant (if not available, use 2P2506 Thread Lubricant) on the bolt threads and contact surfaces of the bolts.

c. Hand tighten bolts (11) and (12) to a torque of 90 ± 5 N·m (65 ± 4 lb ft).

d. Hand tighten bolts (13) and (14) to a torque of 90 ± 5 N·m (65 ± 4 lb ft).

e. Hand tighten bolts (11) and (12) to a torque of 90 ± 5 N·m (65 ± 4 lb ft).

f. Hand tighten bolts (13) and (14) to a torque of 90 ± 5 N·m (65 ± 4 lb ft).

g. Hand tighten each bolt an additional 90 ± 5°.

NOTE: Do not turn the crankshaft when the Plastigage is installed.

h. Remove the rod cap, and measure the Plastigage. The rod bearing clearance must be 0.107 to 0.218 mm (.0042 to .0086 in).

12. Put Fel-pro C100 Lubricant (if not available, use 2P2506 Thread Lubricant) on the bolt threads and contact surfaces of the bolts before final assembly. Put clean engine oil on both halves of the rod bearings. Put clean engine oil on both halves of the rod bearings. Put cap (2) in position, and tighten the bolts as in Steps 11c through 11g. An impact wrench can be used for the final tighten torque of 90 ± 5°.

13. Make sure the dowels are in position and install counterweights (1) on the crankshaft. Prior to assembly, put 334-0519 Grease on the bolt threads, shank, and the underside of the bolt head and install them. Do not use any other lubricant on the bolt threads.

NOTE: For a 3508 only, tighten the bolts in counterweights 1 and 8 to 200 ± 5 N·m (148 ± 4 lb ft), then loosen the bolts in counterweights 1 and 8.

14. Tighten the bolts in all the counterweights evenly to a torque of 70 ± 5 N·m (50 ± 4 lb ft), then tighten the bolts in 120 ± 5° more.

End By:

a. install rocker shaft assemblies and push rods

b. install front drive housing

c. install front balancer group (3508 only)

d. install rear gear group

e. install piston cooling jets