Yanmar 4LHA-HTP Operation Manual page 448

Chapter 3 Fuel Injection Equipment
3. Disassembly, Reassembly and Inspection of Fuel Injection Pump
3-2 Inspection of fuel injection pump
(1) Inspection of plunger
1) Thoroughly wash the plungers, and replace plungers
that have scratches o n the plunger lead or are
discolored.
2) The plunger is in g o o d condition if it slides down
smoothly when it is tilted at about 60°. Repeat
this several times w h i l e turning the plunger. Repair
or replace if it slides d o w n too quickly or if it stops
part way.
(2) Inspection of delivery valve
1) Replace as a set if the delivery valve suck-back
collar or seat is scratched, scored, scuffed, worn,
etc.
2) The valve is in good condition if it returns when
released after being pushed down with your finger
(while the holes in the bottom of the delivery
guide seat are covered). Replace if necessary.
3) Likewise, the valve should completely close by its
own weight when you take your finger off the
holes in the bottom of the delivery guide sheet.
NOTE: When fitting new parts, wash with diesel oil
and perform the above inspection.
(3) Inspection of pump
1) Inspect for extreme wear of the roller guide slid-
ing surface. Scratches on the roller pin sliding sur-
face are not a problem.
2) Inspect the plunger barrel seat.
If there are burrs or discoloration, repair or replace
as this will lead to dilution of the lubricant.
(4) Inspection of fuel camshaft and bearings
1) Fuel camshaft
Inspect for scratches or wear of camshaft, deforma-
tion of key grooves and deformation of screws on
both ends, and replace if necessary.
2) Bearings
Replace if the taper rollers or outer race surface
are flaked or worn.
NOTE: Replace fuel camshafts and bearings together.
(5) Inspection of roller guide assembly
1) Roller
Replace if the surface is worn or flaked.
2) Roller guide
Replace if the roller pin hole and the surface in
contact with the plunger side is extensively worn
or there are many scratches.
3) Replace if the play of the roller guide assembly
pin/roller is 0.2 mm (0.0078 in.) or more.
4) Roller pin
Replace the roller pin if its play in the radial
direction is great.
3-2-26
4LHA Series