3412 INDUSTRIAL & MARINE ENGINES Caterpillar


Crankshaft Main Bearings

Usage:

Remove & Install Crankshaft Main Bearings

Start By:

a. remove oil pump

1. Check each main bearing cap (2) for its location on the engine. Each cap has an arrow (1) which point to the front of the block and a number (3) which gives the location of that cap.

2. Remove No. 2 through No. 6 main bearing caps from the engine. Remove the lower bearings from the caps.

3. Remove the thrust plate from each side of the No. 4 upper main bearing.


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.


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

NOTE: The following steps are for the installation of the crankshaft main bearings.


NOTICE

Make sure the upper and lower halves of bearings are installed so bearing tabs (5) fits into the notch in cylinder block and bearing caps.


NOTE: Do not put oil on the parts until the bearing clearance has been checked.

5. Put clean engine oil on the lower. Install lower bearings in the bearing caps.

6. Put clean engine oil on the upper bearings. Install upper bearing in the cylinder block with Tool (A).

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 bearing to get the 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, it is not necessary to hold the crankshaft up. Do not turn the crankshaft when the Plastigage is in position to check clearances.

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

a. Put a piece of Plastigage on the surface of the lower bearing half.

b. Install the main bearing caps with arrow (6) toward the front of the cylinder block. Each cap has a number (7) on the bottom surface and must be installed in the same position as the correct number on the left side of the cylinder block.

c. Put 2P2506 Thread Lubricant on the threads of the caps bolts. Install the cap bolts finger tight.

d. Tighten the bolts on the tab end of the caps first to a torque of 260 ± 14 N·m (190 ± 10 lb ft)

e. Tighten the bolts on the other end of the caps to a torque of 260 ± 14 N·m (190 ± 10 lb ft)

f. Put a mark across the bolt head and cap. Tighten the bolts opposite the tab end 120°. Tighten the bolts on the tab end of the cap 120°.


NOTICE

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


8. Remove the caps and measure the Plastigage. The clearance for new bearings must be 0.091 to 0.0186 mm (.0036 to .0073 in). The maximum clearance for used bearings is 0.25 mm (.010 in).

9. Install a thrust plate (8) on each side of the No. 4 upper bearing. Install the thrust plates with the side marked "Block Side" toward the cylinder block.

10. Install again the No. 2 through No. 6 main bearing caps. Follow the tightening procedure in Step 7.

11. Do Steps 2, 4, 5, 6, 7 and 8 for the No. 1 and No. 7 main bearing caps.

12. Check the crankshaft end play with Tool (C). The end play is controlled by the thrust plates on the center main bearing. Make sure the dial indicator is against a machined surface. End play for new thrust plates must be 0.15 to 0.51 mm (.006 to .020 in). The maximum end play with used thrust plates is 0.89 mm (.035 in).

End By:

a. install oil pump

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