1.3 Crankshaft
DETROIT DIESEL 53
cracks (45 with the axis of the shaft) starting from either the critical fillet locations or the connecting rod journal holes as
shown in Fig. 6. Replace the crankshaft when cracks of this nature are found.
Crankshaft Grinding
In addition to the standard size main and connecting rod bearings, .002 ", .010 ", .020" and .030" undersize bearings are
available.
NOTE: The .002 " undersize bearings are used only to compensate for slight
wear on crankshafts on which regrinding is unnecessary.
If the crankshaft is to be reground, proceed as follows:
1. Compare the crankshaft journal measurements taken during inspection with the dimensions in Table 1 and Fig . 7
and determine the size to which the journals are to be reground.
2. If one or more main or connecting rod journals require grinding, then grind all of the main journals or all of the
connecting rod journals to the same required size.
3. All journal fillets on the In-line crankshafts must have a .130" to .160" radius. The fillet must blend smoothly into the
journal and the crank cheek and must be free of scratches. The radius may be checked with a fillet gage.
4.
Care must be taken to avoid localized heating which
Bearing
Conn. Rod
Main Bearing
Size
Journal Dia.
Journal Dia.
In-Line Engines
Standard
2.499"/2.500"
2.999"/3.000"
.002" Undersize
2.497"/2.498"
2.997"/2.998"
.010" Undersize
*2.489"/2.490"
*2.989"/2.990"
.020" Undersize
*2.479"/2.480"
*2.979"/2.980"
.030" Undersize
*2.469"/2.470"
*2.969"/2.970"
*Dimension of reground crankshaft
TABLE 1
often produces grinding cracks. Cool the crankshaft while grinding, using coolant generously. Do not crowd the grinding
wheel into the work.
5. Polish the ground surfaces to an 8-12 R.M.S. finish. The reground journals will be subject to excessive wear unless
polished smooth.
6. If the thrust surfaces of the crankshaft (Fig. 10) are worn or grooved excessively, they must be reground and
polished. Care must be taken to leave a .130" to .160" radius on the In-line crankshaft between each thrust surface and
the bearing journal.
7.
Stone the edge of all oil holes in the journal surfaces smooth to provide a radius of approximately 3/32 ".
8. After grinding has been completed, inspect the crankshaft by the magnetic particle method to determine whether
cracks have originated due to the grinding operation.
9.
De-magnetize the crankshaft.
10. Remove the plugs and clean the crankshaft and oil passages thoroughly with fuel oil. Dry the shaft with compressed
air and reinstall the plugs.
Install Crankshaft
If a new crankshaft is to be installed, steam clean it to remove the rust preventive, blow out the oil passages with
compressed air and install the plugs. Then install the crankshaft as follows:
1.
Assemble the crankshaft timing gear (Section 1.7.5) and the oil pump drive gear (Section 4.1) on the crankshaft.
2. Refer to Section 1.3.4 for main bearing details and install the upper grooved bearing shells in the block. If the old
bearing shells are to be used again, install
Thrust Washer
Nominal
Thickness
Size
Min.
Max.
Standard
.1190"
.1220"
.005" Oversize
.1255"
.1270"
.010" Oversize
.1300"
.1320"
TABLE 2
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