OPERATION, LUBRICATION, MAINTENANCE AND TUNE-UP
59
VALVE CLEARANCE
ADJUSTMENT (ALL MODELS)
Adjusting screw
SPEED ADJUSTMENT
(1 GM AND 1
MODELS)
speed
screw
rough engine operation and possible engine damage, such
as burnt valves. Excessive valve clearance will reduce en-
gine performance. The recommended interval for valve
adjustment is after every 300 hours of operation. How-
ever, it is a good practice to check the valve clearances
during each tune-up.
The engine must be cold when adjusting valve clear-
ance. On multicylinderengines, the cylinder nearest the
flywheel is the number one cylinder.
1. Remove the rocker arm cover as described in Chapter
Five or Six.
2.
the flywheel (A, Figure 31) through the open-
ing in the clutch cover. A cylinder is at top dead center if
the mark on the flywheel is aligned with the reference
pointer (B) on the clutch cover.
3. Rotate the crankshaft with a wrench on the crankshaft
pulley retaining nut (Figure 32).
CA UTION
Always rotate the crankshaft in the normal
running direction (clockwise at crankshaft
pulley); otherwise the water pump impeller
will be damaged.
4. Rotate the crankshaft nut clockwise so the
mark on
the flywheel aligns with the reference pointer (B, Figure
31) on the clutch cover. The piston must be on its com-
pression stroke.
NOTE
Some transmissions do not have an opening
in the clutch
Remove the starter to
view the timing marks on the flywheel
(Fig-
ure 33).
NOTE
When thepiston is on its compression stroke
and at top dead
both valves will be
closed. This can be determined by the posi-
tion of the intake and exhaust rocker arms.
Both should have free play, which indicates
that the valves are closed.
5. Measure the clearance between the rocker arm and
valve stem (Figure 34). Correct valve clearance is 0.2 mm
(0.008 in.).
6. If the clearance is incorrect, loosen the locknut, then
rotate the adjusting screw on the rocker arm (Figure 34).
Hold the adjusting screw, then tighten the locknut. Re-
check the valve clearance.
7A. 2GM and
engines-Rotate the crankshaft
so the 2T mark on the flywheel aligns with the refer-
ence pointer (B, Figure 31) on the clutch cover. The pis-
ton for number 2 cylinder must be on its compression
stroke (see preceding NOTE). Perform Steps 5 and 6.
7B.
3HM and
engines-Rotate
the crankshaft
so the 3T mark on the flywheel aligns
with the reference pointer (B, Figure 31) on the clutch
cover. The piston for number 3 cylinder must be on its
compression stroke (see preceding NOTE). Perform Steps
5 and 6.
8. Reinstall the rocker arm cover.
Idle Speed Adjustment
The correct idle speed is 825-875
Refer to the fol-
lowing procedure to adjust the idle speed.
1. Run the engine until it reaches normal operating tem-
perature.
2. Place the transmission in neutral.
3. Loosen the jam nut on the idle speed screw (Figure 35
or Figure 36).
Summary of Contents for 1GM10
Page 1: ...YANMAR DIESEL INBOARD SHOP MANUAL ONE TWO 8 THREE CYLINDER ENGINES...
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Page 28: ...GENERAL INFORMATION 21 Bearing Blocks Press Shaft arm Bearing Spacer Press k 4 bed...
Page 36: ...30 CHAPTER TWO CHARGING SYSTEM TYPICAL Battery switch...
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Page 44: ...38 CHAPTER TWO LUBRICATION SYSTEM 2GM AND 2GM20 MODELS...
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Page 112: ...106 CHAPTER SIX...
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Page 145: ...FUEL INJECTION AND GOVERNOR SYSTEMS 139 FUEL INJECTION SYSTEM Fuel tank hose fuel pipe...
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Page 170: ...164 CHAPTER EIGHT CLOSED COOLING SYSTEM TYPICAL rnlxlng elbow Joint...
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Page 224: ...218 CHAPTER ELEVEN...
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