BAR 1V3584 - Caterpillar

Remove & Install Crankshaft Main Bearings
Start By:a. remove oil pumpFluid Spillage Containment
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to "Tools And Shop Products Guide", NENG2500 for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose fluids according to local regulations and mandates. 1. Check each main bearing cap (2) for its location on the engine. Each cap has an arrow (1) which points to the front of the block and a number (3) which gives the location of that cap.2. On the 3408 Engines, remove No. 2 through No. 4 main bearing caps from the engine. On the 3412 Engines remove No. 2 through No. 6 main bearing caps from the engine. Remove the lower bearings from the caps.3. Remove the thrust plates from each side of the No. 3 main bearing on the 3408 Engines and from the No. 4 main bearing on the 3412 Engines.
If the crankshaft is turned in the wrong direction, the tab of 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.
Make sure the upper and lower halves of bearings are installed so bearing tabs (5) fit into the notch in cylinder block and bearing caps.
Do not put oil on parts until the bearing clearance has been checked.5. Use Tool (A) to install the upper bearings in the block. Make sure that the end of the bearing, without the tab, goes into the engine block first.6. Install the lower bearings in the bearing cap. When the bearing clearance is checked and the engine is in a vertical position, 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, it is not necessary to hold the crankshaft up. Do not turn the crankshaft when the Plastigage is in position to check clearances. See the Topic, "Install Crankshaft", for more information on the use of Plastigage.7. Check the bearing clearance with Plastigage (B) as follows: a. Put a piece of the 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 clean oil on the threads of the cap