Generac Power Systems GTH1000, Руководство по обслуживанию

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GENERAL INFORMATION
It is recommended that new piston rings be installed whenever the
engine is disassembled for major servicing or overhaul, providing that
cylinder bores are within specification.
Measure cylinder bores before checking pistons and rings. See Sec-
tion 10. If cylinder bores are out of tolerance, a new crankcase will
be needed.
If the cylinder bore is more than .075 mm (.003") oversize, or 0.035
mm (0.0015") out of round, it must be replaced.
DISASSEMBLE PISTON AND CONNECTING ROD
1. Remove piston compression rings using a ring expander similar
to the one shown in Figure 12-1.
a. Then remove oil ring.
Figure 12-1. Remove Rings
Figure 12-2. Remove Piston Pin Locks
2. Disassemble piston from connecting rod, Figure 12-2.
a. Remove piston pin locks.
b. Piston pin is a slip fit in piston and connecting rod.
Keep pistons and connecting rods together as an assembly. Do not mix.
CHECKING PISTON AND RINGS
If the cylinder is not going to be replaced and the piston shows no
signs of scoring, the piston should be checked. Carefully remove
carbon from ring grooves.
1. Check side clearance of ring grooves using new rings, Figure 12-3.
If a 0.10mm (0.004”) feeler gauge for the compression rings or
0.20mm (0.008”) for the oil ring can be inserted, the ring groove
is worn. The piston must be replaced.
Figure 12-3. Check Ring Grooves
2. Check ring end gap, Figure 12-4.
a. Using a new ring, insert approximately 1" (25 mm) into cylinder.
b. If gap is less than the standard dimension, remove some mate-
rial from the end of the ring with a very fine file to achieve the
minimum gap.
3. Check piston pin bore, Figure 12-5.
a. Replace if greater than 20.03mm (.7886") or if it is 0.01mm
(0.0005") out of round.
SECTION 12: PISTON, RINGS & CONNECTING ROD INSPECTION & ASSEMBLY
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