Yanmar 4LHA-HTP User Manual

Chapter 2 Basic Engine
9. Timing Gear
, 4LHA Serie,
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
Idle gear Camshaft gear
Sea water pump gear
Lubricating oil pump gear Direction of rotation Crankshaft gear
Crankshaft gear
Idle gear
Lube oil pump gear
Injection pump gear
Camshaft gear
Sea water pump gear
No. of teeth
24 51
20
48
48
27
Back lash
0.08~0.16mm(0.0031 ~0.0063in.)
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.
mm (in.)
Standard Wear limit
Idle shaft dia.
45.95 - 45.975
(1.8091 - 1.8100)
45.9
(1.8071)
Idle shaft bushing
inside dia.
46.00 - 46.025
(1.8110-1.8120)
46.09
(1.8146)
Idle shaft and bushing
oil clearance
0.025 - 0.075
(0.0010-0.0030)
-
(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

Yanmar 4LHA-HTP Specifications

General

Brand	Yanmar
Model	4LHA-HTP
Category	Engine
Language	English