Timing Gear - Yanmar 4LHA-HTP Operation Manual

Chapter 2 Basic Engine

9. Timing Gear

9. Timing Gear
The timing gear is helical type for minimum noise and
specially treated for high durability.
Match up the timing marks on each gear when assembling
(A, B and C).
Fuel injection pump gear
Crankshaft gear
No. of teeth
Back lash
9-1 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 ex-
cessive noise and gear damage, but also lead to
bad valve and fuel injection timing and a decrease
in engine performance.
45.95 - 45.975
Idle shaft dia.
(1.8091 - 1.8100)
46.00 - 46.025
Idle shaft bushing
(1.8110-1.8120)
inside dia.
0.025 - 0.075
Idle shaft and bushing
(0.0010-0.0030)
oil clearance
Idle gear
Lubricating oil pump gear Direction of rotation
Idle gear
24 51
mm (in.)
Standard Wear limit
45.9
(1.8071)
46.09
(1.8146)
-
Crankshaft gear
Lube oil pump gear Injection pump gear
20 48
0.08~0.16mm(0.0031 ~0.0063in.)
(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.
2-35
Camshaft gear
Sea water pump gear
Camshaft gear Sea water pump gear
48
, 4LHA Serie,
27