Volvo Penta TAD1630G Workshop Manual page 72

Service procedures - engine
D. Check for cracks
Checking must be carried out after alignment and before and
after grinding.
To check, use a magnetic powder test of type Magnaglo, i.e.
fluorescent powder which can be seen under ultraviolet light.
Refer to manufacturer's instructions on the method to be
adopted. When assessing the cracks, the following applies:
1
The shaft must be scrapped if there are longitudinal cracks
on the journals and in the fillets.
2
The shaft must be scrapped if there are crosswise cracks
within the marked zone. This applies to both crank pins and
main bearing journals.
70
3
The shaft must be scrapped when cracks longer than 5 mm
(0.2") are adjacent to the area around the oil holes. Cracks
shorter than 5 mm (0.2") can be removed by grinding.
4
The shaft must be scrapped when cracks are longer than 10
mm (0.4") outside the marked area. Isolated cracks less
than 10 mm (0.4") are acceptable.
Group 21