DETROIT DIESEL 53
cracks (45o with the axis of the shaft) starting from
often produces grinding cracks. Cool the crankshaft
while grinding, using coolant generously. Do not
either the critical fillet locations or the connecting rod
crowd the grinding wheel into the work.
journal holes as shown in Fig. 6. Replace the
crankshaft when cracks of this nature are found.
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
In addition to the standard size main and connecting
rod bearings, 002", .0 10 ", .020 " and .030 " undersize
worn or grooved excessively, they must be reground
and polished. Care must be taken to leave a .130" to
bearings are available.
.160" radius on the In-line crankshaft
NOTE: The 002 " undersize bearings are used
thrust surface and the bearing journal.
o n l y to compensate for slight wear on
crankshafts on which regrinding is unnecessary.
7. Stone the edge of all oil holes in the journal surfaces
smooth to provide a radius of approximately 3/32".
If the crankshaft is to be reground, proceed as follows:
8. After grinding has been completed, inspect the
1. Compare the crankshaft journal measurements
crankshaft by the magnetic particle method to
taken during inspection with the dimensions in Table
determine whether cracks have originated due to the
and determine the size to which the
I and Fig . 7
journals are to be reground.
9. De-magnetize the crankshaft.
2. If one or more main or connecting rod journals
require grinding, then grind all of the main journals
10. Remove the plugs and clean the crankshaft and oil
or all of the connecting rod journals to the same
passages thoroughly with fuel oil. Dry the shaft with
compressed air and reinstall the plugs.
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
If a new crankshaft is to be installed, steam clean it to
remove the rust preventive, blow out the oil passages
4. Care must be taken to avoid localized heating which
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
2. Refer to Section 1.3.4 for main bearing details and
install the upper groovedbearing shells in the block. If
the old bearing shells are to be used again. install
*Dimension of reground crankshaft