If they appear damaged or deteriorated, replace them.

Balancer Adjustment
Torque LimiterNozzle Assy Installation
Replace the dust seals [A] with new ones.
Apply engine oil to the new dust seals, and install them.
Install the nozzle assy securely.
Push the four mounting positions of the injectors.
Set the joint pipe parallel to the air cleaner housing [B].
NOTICE
When installing the nozzle assy, ap ...
Oil Seal, Grease Seal
Do not remove pressed oil or grease seals unless removal
is necessary. Replace with new ones whenever removed.
Press new oil seals with manufacture and size marks facing
out. Make sure the seal is aligned properly when installing.
Apply specified grease to the lip of seal before installing ...
Air Cleaner Housing Assembly
Install the ducts to the air cleaner housing.
Fit the projections [A] of the duct into the slits [B] on the
air cleaner housing.
Tighten the screws [A].
Torque - Air Cleaner Housing Duct Screws: 1.1 N·m (0.11
kgf·m, 10 in·lb)
Install:
Air Cleaner Gasket [A]
Duct [B] ...