Crankshaft Runout Figure 12-64 Measure Tool Required: J 7872 Magnetic Base Dial Indicator 1 . Crankshaft run-out. A . Mount the crankshaft in V-blocks at crankshaft journals 1 and 4. B . Use a dial indicator as shown (figure 12-64). C . If the main journals are misaligned, the crankshaft is bent and must be replaced. The main bearings must also be replaced at the same time. D . Grind or replace the crankshaft if necessary. In general, the lower inserts (except the # 1 bearing) show the greatest wear and distress from fatigue. Upon inspection, if a lower insert is suitable for reuse, it can be assumed that the upper insert is also satisfactory.
If a lower insert shows evidence of wear or damage, both the upper and lower inserts must be replaced. b . Tighten bolts to specification. c. Firmly thrust end of the crankshaft first rearward then forward. This will line up the rear main bearing and crankshaft thrust surfaces. d. With the crankshaft wedged forward, measure at the front end of the rear main bearing with a feeler gage (figure 12-65). Refer to “Specifications”. IMPORTANT: If correct end play cannot be obtained, be certain that the correct size rear main bearing has been installed. Some production engines may use crankshaft bearings that are wider across the thrust faces than standard size bearings.
Refer to “Specifications” for available bearing sizes. Inspect • Crankshaft for binding. Turn crankshaft to check for binding. If the crankshaft does not turn freely, loosen the crankshaft bearing bolts, one pair at a time until the tight bearing is located. Burrs on the bearing cap, foreign matter between the bearing and the block or the bearing cap, or a faulty bearing could cause a lack of clearance at the bearing. Figure 12-64 Measuring Crankshaft Runout Crankshaft End Play Figure 12-65 Measure • Crankshaft end play as follows: a . Install crankshaft bearings, crankshaft, caps, and bolts.
Figure 12-65 Measuring Crankshaft End Play Connecting Rod Bearings Follow all procedures outlined for crankshaft bearing cleaning, inspection, and measurement. Refer to “Specifications”. G643 (E) Service Manual Chapter 3. Engine Mechanical System 93