Yanmar 4BY, Service Manual, Page: 103 / 275

ENGINE
5-48
BY Service Manual
Camshaft and Timing Gear Train
Checking and Adjusting Camshaft
Timing
Checking Camshaft Timing
1. Remove cylinder head cover. See Remove and
Install Cylinder Head Cover on page 5-20.
Figure 5-70
2. Rotate the crankshaft in the normal running
direction until No. 1 cylinder is at TDC of the
power stroke. The front lobe of each camshaft
(Figure 5-70, (1)) will be facing the exhaust
side.
3. Verify position by checking the camshaft timing
marks (Figure 5-70, (2)) on gears are aligned.
The single mark on intake camshaft gear must
fall between the two marks on the exhaust
camshaft gear.
Figure 5-71
IMPORTANT
DO NOT rotate the crankshaft backward. If
the crankshaft is turned past TDC, rotate
two more turns (720°) to bring No. 1 piston
back to TDC.
4. Secure crankshaft in TDC position with flywheel
holding tool OEM No. 11 5 180 (Figure 5-71) .
Figure 5-72
Note: Special tool shown on intake camshaft.
Exhaust camshaft is checked in the
same manner but has no adjustment. If
camshaft gears are properly aligned,
exhaust camshaft timing must be correct.
5. Install special tool OEM No. 11 6 321
(Figure 5-72, (1)) on the flats of the intake
camshaft (Figure 5-72, (2)) . The tool must set
firmly on the machined gasket surface
(Figure 5-72, (3)) on each side of the cylinder
head. If it does not, the timing must be adjusted.
See Adjusting Camshaft Timing on page 5-49.
6. Remove special tools.
7. Assemble engine.
000 3 771
(2)
(1)
000 3 772
( 3 )
( 3 )
(2)
(1)