Yanmar 4JH4E - Timing Gear; Inspecting the Gears; Gear Timing Marks

5. Inspection and servicing of basic engine parts
212
5.7 Timing gear
The timing gear is helical type for minimum noise
and specially treated for high durability.
5.7.1 Inspecting the gears
(1) Inspect the gears and replace if the
teeth are damaged or worn.
(2) Measure the backlash of all gears that
mesh, and replace the meshing gears
as a set if wear exceeds the limit.
Note:
If backlash is excessive, it will not only result
in excessive noise and gear damage, but
also lead to bad valve and fuel injection
timing and a decrease in engine
performance.
(3) Idling gear
The bushing is pressure fitted into the idling
gear.
Measure the bushing inner diameter and the
outer diameter of the shaft, and replace the
bushing or idling gear shaft if the oil clearance
exceeds the wear limit.
A, B and C are inscribed on the end of the
idling gear.
When assembling, these marks should align
with those on the cylinder block.
5.7.2 Gear timing marks
Match up the timing marks on each gear when
assembling (A, B and C).
mm
Standard Limit
Backlash 0.07-0.15 0.17
mm
Standard Limit
Idle gear shaft dia. 45.950-45.975 45.880
Idle gear bushing inside dia. 46.000-46.025 46.075
Oil clearance 0.025-0.075 0.15
Idle gear shaft
Idle gear bushing
Idle gear
010552-00E
A
B
C
Fuel injection pump drive gear
Camshaft gear
Seawater pump gea
r
Idle gear
Crankshaft gear
010553-00E