Crankshaft & Main Bearings
- Note that main bearing caps are numbered for location and arrow on cap points toward front of engine. Loosen main bearing cap bolts in sequence using several steps. See Fig 1 and Fig 2 .
- Cylinder block main bearing bore inside diameter is determined by size mark ("1", "2" or "3") stamped on cylinder block oil pan rail. See Fig 3. Front size mark is for front or No. 1 bore.
- Crankshaft main bearing journal diameter is determined by size mark ("0", 1" or "2") stamped on crankshaft counterweight. See Fig 3. Ensure main bearing journal diameter, taper and out-of-round are within specification. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table under ENGINE SPECIFICATIONS.
- Main bearing size mark ("1", "2", "3", "4" or "5") is stamped on side of main bearing. See Fig 3. If replacing main bearing, ensure size mark on replacement bearing is same as size mark on original bearing.
- If bearing size mark cannot be obtained, add size marks on cylinder block and crankshaft to determine size mark of main bearing. For example, if size mark on cylinder block is "2" and size mark on crankshaft is "1", use main bearing with size mark "3".
- Main bearing thickness is determined by size mark. See MAIN BEARING SPECIFICATIONS table. Coat threads and seat area of main bearing cap bolt with engine oil before installing bolt.CAUTION: Install main bearing caps with arrows on top of caps pointing toward front of engine. Ensure caps are installed in numerical order, with No. 1 cap at front of engine and No. 7 cap at flywheel end.
- Tighten main bearing cap bolts to specification in sequence. See Fig 1 and Fig 2 . See appropriate TORQUE SPECIFICATIONS table.
- Ensure crankshaft end play and main bearing oil clearance are within specification. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS table. Replace thrust bearing if end play is not as specified.
MAIN BEARING SPECIFICATIONS
| Bearing Size Mark | Thickness: In. (mm) |
|---|---|
| "1" | .0783-.0784 (1.988-1.991) |
| "2" | .0784-.0785 (1.991-1.994) |
| "3" | .0785-.0786 (1.994-1.996) |
| "4" | .0787-.0788 (1.998-2.001) |
| "5" | .0788-.0789 (2.001-2.004) |