Doosan G430 LP Service Manual page 162

VE096-3L
4. Reconditioning the valve seats is very important.
5. Recondition the valve seat after reaming the valve
guide bores or installing the new valve guides.
• The valves must seat perfectly for the engine to
deliver optimum power and performance.
• Cooling the valve heads is another important factor.
Good contact between each valve and its seat in
the cylinder head is necessary to ensure that the
heat in the valve head is properly carried away.
• Regardless of what type of equipment is used, it is
essential that the valve guide bores are free from
carbon or dirt to ensure the proper centering of the
pilot in the guide.
• The valve seats should be concentric to within
0.0508 mm (0.002 in) total indicator reading.
LP Engine G430 (3.0L)
VE097-3L
6. Reface pitted valves on a valve refacing machine in
order to ensure the correct relationship between the
head and the stem.
• Replace the valves that show excessive wear or
are warped.
• Replace the valve if the edge of the head is less
than 0.8 mm (0.031 in) thick after grinding.
• Several different types of equipment are available
for reconditioning valves and valve seats. Use the
manufacturers recommendations of equipment to
obtain the proper results.
- 161 - Base Engine Service Procedure