Doosan DISD SD 310 Shop Manual page 167

Caution:
When the bolts are tightened, remove the guide bar.
²The flywheel housing is assembled after the new oil
seal was pressed (Coat engine oil over the outside of oil
seal) before in the housing by a press.
²If any peripheral scar was generated due to oil seal at
the oil seal contact surface of crankshaft, after inserting
about 1 mm shim or thereabout in front of oil seal
(Direction toward crankshaft.), measure and adjust.
3.3.7 Oil seal (Rear side)
²Apply lubricating oil to the outside of the oil seal and
flywheel housing inside diameter and fit them over the
crank shaft, then assemble the oil seal using an oil seal
fitting jig.
3.3.8 Flywheel
²Installation of flywheel ring gear
With a gas burner, heat the ring gear evenly until heat
expansion takes place, then install it using a hammer.
Caution:
Do not allow the temperature of the ring gear to
exceed 200 ° C (390 ° F).
²By means of mandrel, assemble pilot bearing to the
flywheel.
²By means of mandrel, press in the wear ring at the
backward face.
5ton Diesel Engine SPC000006
Page 67