Husqvarna S427 Operator's Manual page 19

Changing Hydraulic Oil and Filter
NOTE: Change the hydraulic oil and oil filter
every season or 100 hours.
1. Clean area around hydraulic supply
hose.
2. Place container under oil filter and
hydraulic supply hose to catch oil.
3. Remove hose clamp and disconnect
hose from hydraulic tank.
Hydraulic
Supply Hose
4. Remove oil filter.
5. Allow tank to drain.
6. Reinstall hydraulic suction hose and
tighten hose clamp.
7. Lubricate rubber gasket on new oil filter
with clean hydraulic oil.
8. Spin new oil filter onto filter housing
until it makes contact. Tighten oil filter
another half turn.
9. Add new oil to the oil tank.
10. Check hydraulic oil level.
11. Properly dispose of waste oil.
Hydraulic System Purge
Hydraulic Tank
- 19 -
1. With the engine running, extend the
hydraulic cylinder out fully and then
retract fully.
2. Repeat four to five times. Erratic
movement in the hydraulic cylinder
indicates that there is air in the system.
3. Stop the engine and check the
hydraulic oil level. Add if necessary.
4. Repeat extending and retracting
of hydraulic cylinder unit motion
is consistent and smooth in both
directions.
5. Ensure the hydraulic oil is at proper
level.
IMPORTANT At this point a large amount
of hydraulic oil has been drawn into the
hydraulic cylinder and hoses. Be sure
to refill the oil reservoir to prevent pump
damage.