Yanmar 4LHA-HTP Operation Manual page 510

Chapter 5 Lubrication System
2. Lube Oil Pump
2-3 Lube oil pump disassembly
(1) Remove the lube oil pump assembly from the engine
plate.
(2) The lube oil pump cover may be disassembled, but
do not disassemble the rotor, rotor shaft or drive gear.
The oil pressure regulating valve plug is coated with
adhesive and screwed in, so it cannot be disassembled.
These parts cannot be reused after disassembly.
Replace if necessary as an assembly.
2-4 Lube oil pump inspection
(1) Clearance between outer rotor and pump body
Insert a feeler gauge between the outer rotor and pump
body to measure the clearance, and replace if it ex-
ceeds the limit.
Outer rotor and
pump body clearance
(2) Clearance between outer rotor and inner rotor
To measure clearance, insert a feeler gauge between
the top of the inner rotor tooth and the top of the outer
rotor tooth, and replace if it exceeds the limit.
Outer rotor
Body
Feeler gauge
Standard
Wear limit
0.100-0.155
0.20
(0.0039 - 0.0061)
(0.0098)
Inner rotor
Outer rotor
Feeler gauge
Outer rotor and
inner rotor clearance
(3) Clearance between pump body and inner rotor side of
outer rotor
Place a straight-edge against the end of the pump body
and insert a feeler gauge between the straight-edge
and the rotor to measure side clearance. Replace the
assembly if the clearance exceeds the limit.
Pump body and inner rotor,
outer rotor clearance
(4) Check for looseness of driver gear/rotor shaft fitting, and
replace the entire assembly if loose or wobbly.
(5) Push the oil pressure regulating valve piston from the oil
hole side, and replace the assembly if the piston does not
return due to spring breakage, etc.
(6) Make sure that the rotor shaft rotates smoothly and easily
when the drive gear is rotated.
5-5
4LHA Sen
Clearance
Inner rotor
Outer rotor
Standard
Wear limit
0.050 ~ 0.105
0.15
(0.0019 ~ 0.0041)
(0.0059)
Straight scale
Body
Feeler gauge
Standard
Wear limit
0 . 0 5 - 0 . 1 0
0.13
(0.0020 - 0.0039)
(0.0051)