Service Manual

Crankshaft Bearings (Fig. 68, 69)

1. Measure the crankshaft for “run-out” (bend). Mount

the crankshaft in a pair of V-blocks (or live centers) and

use a dial indicator to measure the run-out in the crank-

shaft. The maximum allowable crankshaft run-out is

.0012 inch (0.03 mm).

2. Check the crank journals and crank pins for damage

suc

h as galling, seizure, etc. If journals or pins are

seriously damaged they may be reground and over-

sized bearings installed. The main bearing and connect-

ing rod bearing oil clearances may be measured with a

micrometer or Plastigauge. Crankshaft oil clearances

are: Journal, 0.0039 inch (0.10 mm); Crank pin, 0.0059

inch (0.15 mm).

NOTE: When using Plastigauge to measure the clear-

ce between the crankshaft and its bearings, install the

crankshaft into the cylinder block, place a piece of

Plastigauge onto the crank pin or journal, and torque the

bearing cap (with bearing) in place.

DO NOT TURN THE

CRANKSHAFT WHEN PLASTIGAUGE IS IN PLACE SINCE

THE PLASTIGAUGE WOULD BE DESTROYED

. Remove

the bearing cap and measure the width of the Plasti-

gauge to determine the clearance. If the oil clearances

exceed these amounts attempt to install a new bearing

to reduce the clearance. If installing a replacement

bearing does not reduce the clearance to within toler-

ance the crankshaft must be reground and an oversized

bearing installed.

Timing Gears (Fig. 70)

1. Inspect the idler gear, fuel injection pump gear, cam-

shaft gear and crankshaft gear for wear or damage.

Replace these gears if defective.

Figure 68

Figure 69

Figure 70

Cylinder Block Overhaul Page 4 - 56 Groundsmaster

300 Series