Crankshaft Main Bearing: Service and Repair
FITTING MAIN BEARINGSRefer to the Standard Service Procedures for Measuring Main Bearings. For Crankshaft specifications refer to Crankshaft Specification Chart.
CRANKSHAFT MAIN BEARINGS
Figure 10:
The crankshaft is supported in five main bearings. All upper and lower bearing shells in the crankcase have oil grooves. The number three lower main thrust bearing is plain. Crankshaft end play is controlled by a flanged bearing on the number three main bearing journal (Fig. 10).
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. 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.
CRANKSHAFT SPECIFICATION CHART
MAIN BEARING INSTALLATION
Figure 11:
1. Install the main bearing shells with the lubrication groove in the cylinder block (Fig. 11).
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.
Figure 12:
4. Apply 1.5 to 2.0 mm (0.059 to 0.078 inch) bead of anaerobic sealer Mopar(R) Torque Cure Gasket Maker to cylinder block as shown (Fig. 12).
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 its furthest forward position.
Figure 13:
- Step 5: Install and tighten bolts (1 - 10) in sequence shown 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 (Fig. 13).
10. Install main bearing bedplate to engine block bolts (11 through 20) and torque each bolt to 28 Nm (20 ft. lbs.) in sequence shown.
11. After the main bearing bedplate is installed, check the crankshaft turning torque. The turning torque should not exceed 5.6 Nm (50 inch lbs.).
CRANKSHAFT END PLAY
Figure 14:
1. Mount a dial indicator to front of engine, locating probe on nose of crankshaft (Fig. 14).
2. Move crankshaft all the way to the rear of its travel.
3. Zero the dial indicator.
4. Move crankshaft all the way to the front and read the dial indicator. Refer to Crankshaft Specification Chart for end-play specification.
Crankshaft Specification Chart
OPTIONAL CRANKSHAFT END PLAY CHECK
1. Move crankshaft all the way to the rear of its travel using a lever inserted between a main bearing cap and a crankshaft cheek, using care not to damage any bearing surface. DO NOT loosen main bearing cap.
2. Use a feeler gauge between number three thrust bearing and machined crankshaft surface to determine end play.