Main Bearing-Fitting
For crankshaft specifications, refer to Specifications.CRANKSHAFT MAIN BEARINGS
Fig. 15
The crankshaft is supported in five main bearings. All upper and lower bearing shells in the crankcase have oil grooves. Crankshaft end play is controlled by a flanged bearing on the number three main bearing journal (Fig. 15).
Upper and lower Number 3 bearing halves are flanged to carry the crankshaft thrust loads and are NOT interchangeable with any other bearing halves in the engine (Fig. 15). All bearing cap bolts removed during service procedures are to be cleaned and oiled before installation. Bearing shells are available in standard and the following undersized: 0.025 mm (0.001 inch) and 0.250 mm (0.010 inch). Never install an undersize bearing that will reduce clearance below specifications. Replace or machine the crankshaft as necessary to obtain proper bearing clearances.
MAIN BEARING CLEARANCE
1. With engine in the inverted position (crankshaft up) and mounted on a repair stand, remove bedplate and lower main bearings.
2. Remove oil film from surface to be checked. Plastigage is soluble in oil.
3. Clean bedplate to cylinder block sealing locations.
4. Place a piece of Plastigage across the entire width of the bearing surface at each main bearing location, approximately 6.35 mm (1/4 inch) off center and away from the oil holes.
5. Position bedplate (dry-no sealer) on cylinder block and torque the bolts in sequence to proper specifications. Refer to Main Bearing Installation procedure.
Fig. 16
6. Remove the bedplate and compare the width of the flattened Plastigage (Fig. 16) with the metric scale provided on the package. Locate the band closest to the same width. This band shows the amount of clearance in thousandths of a millimeter. Differences in readings between the ends indicate the amount of taper present. Record all readings taken. Refer to Engine; Specifications. Plastigage generally is accompanied by two scales. One scale is in inches, the other is a metric scale.
NOTE: Plastigage is available in a variety of clearance ranges. Use the most appropriate range for the specifications you are checking.
MAIN BEARING INSTALLATION
Fig. 17
1. Install the main bearing shells with the lubrication groove in the cylinder block (Fig. 17).
2. Make certain oil holes in block line up with oil holes in bearings. Bearing tabs must seat in the block tab slots.
CAUTION: Do not get oil on the bedplate mating surface. It will may effect the sealer ability to seal the bedplate to cylinder block.
3. Oil the bearings and journals and install crankshaft.
CAUTION: Use only the specified anaerobic sealer on the bedplate or damage may occur to the engine. Ensure that both cylinder block and bedplate surfaces are clean.
Fig. 18
4. Apply 1.5 to 2.0 mm (0.059 to 0.078 inch) bead of anaerobic sealer Mopar Bed Plate Sealant to cylinder block as shown in (Fig. 18).
5. Install lower main bearings into main bearing cap/bedplate. Make certain the bearing tabs are seated into the bedplate slots. Install the main bearing/bedplate into engine block.
6. Before installing bolts, lubricate the threads with clean engine oil, wipe off any excess oil.
7. Install main bearing bedplate to engine block bolts 11, 17 and 20 finger tight. Tighten these bolts down together until the bedplate contacts the cylinder block.
8. To ensure correct thrust bearing alignment, perform the following steps:
- Step 1: Rotate crankshaft until number 4 piston is at TDC.
- Step 2: Move crankshaft rearward to limits of travel.
- Step 3: Then, move crankshaft forward to limits of travel.
- Step 4: Wedge an appropriate tool between the rear of the cylinder block (NOT BED PLATE) and the rear crankshaft counterweight. This will hold the crankshaft in it's furthest forward position.
Fig. 19
- Step 5: Install and tighten bolts (1-10) in sequence shown in (Fig. 19) to 41 Nm (30 ft. lbs.).
- Step 6: Remove wedge tool used to hold crankshaft.
9. Tighten bolts (1-10) again to 41 Nm (30 ft. lbs.) + 1/4 turn in sequence shown in (Fig. 19).
10. Install main bearing bedplate to engine block bolts (11-20), and torque each bolt to 28 Nm (20 ft. lbs.) in sequence shown in (Fig. 19).
11. After the main bearing bedplate is installed, check the crankshaft turning torque. The turning torque should not exceed 5.6 Nm (50 in. lbs.).