3208 TRUCK ENGINE Caterpillar


Crankshaft Main Bearing

Usage:

Remove And Install Crankshaft Main Bearings

start by:

a) remove oil pan

1. Check each main bearing cap for its location on the engine. Each cap has a number which gives the location of that cap. Make a note that the number on each cap is toward the front of the cylinder block.

2. Remove the bolts and washers that hold main bearing cap (2) in place. Remove the bearing cap and the lower half of the main bearing. Use tool (C) to remove the bolts that hold the No. 1 main bearing cap in position.

3. Remove bearing (1) from the bearing cap.

4. Turn the crankshaft until tool (A) can be installed in the oil hole in the crankshaft journal. Install tool (A). Turn the crankshaft in the direction which will push the upper main bearing out, tab end first.


NOTICE

If the crankshaft is turned in the wrong direction, the tab of the bearing will be pushed between the crankshaft and the cylinder block. This will cause damage to the crankshaft and block.


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

5. Install the lower bearing in the bearing caps. Install upper bearings (bearing with the oil hole) in the cylinder block with tool (A).


NOTICE

When bearing caps are installed, make sure the caps are installed with the part number toward the front of the engine and the number on the bottom of the cap is the same as the number on the camshaft side of the engine.


NOTE: When the bearing clearance is checked and the engine is in a vertical position, such as in the vehicle, the crankshaft will have to be lifted up and held against the upper halves of the main bearings to get a correct measurement with Plastigage (B). The Plastigage will not hold the weight of the crankshaft and give a correct indication. If the engine is in a horizontal position, such as on an engine stand, it is not necessary to hold the crankshaft up. Do not turn the crankshaft when Plastigage (B) is in position.


NOTICE

Do not use an impact wrench to tighten the bolts the additional 120° ± 5°.


6. Check the bearing clearance with Plastigage (B) as follows:

Put cap (3) in position and install the bolts. Tighten bolt (5) to a torque of 30 ± 3 lb. ft. (40 ± 4 N·m). Tighten bolt (4) to a torque of 30 ± 3 lb.ft. (40 ± 4 N·m). Put a mark on both bolt heads and the bearing cap. Tighten bolt (4) 120° ± 5° more. Tighten bolt (5) 120° ± 5° more.

7. Remove the bearing cap and measure the thickness of the Plastigage. The main bearing clearance must be .0030 to .0066 in. (0.076 to 0.168 mm). The maximum permissible clearance is .007 in. (0.18 mm).

8. Put 2P2506 Thread Lubricant on the bolt threads and washer faces. Put clean engine oil on the lower half of the main bearing. Put the bearing cap and lower half of the main bearing in position on the engine. Install the bolts. Tighten bolt (5) to a torque of 30 ± 3 lb. ft. (40 ± 4 N·m). Tighten bolt (4) to a torque of 30 ±3 lb. ft. (40 ± 4 N·m). Put a mark on both bolt heads and the cap. Tighten bolt (4) 120° ± 5° more. Tighten bolt (5)120° ± 5° more.

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

NOTE: When a replacement of the thrust plates on No. 3 main bearing is made, install the thrust plates with the identification "BLOCK SIDE" next to the block.

10. Check the crankshaft end play with tooling (D). The end play is controlled by the thrust bearing on No. 4 main bearing. The end play with new bearings must be .003 to .010 in. (0.08 to 0.25 mm). The maximum permissible end play with used bearings is .014 in. (0.36 mm).

end by:

a) install oil pan

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