Exmark Turf Tracer HP 4500-358 - Manual (Page 30)

Maintenance
5. Loosen filter 1/2 turn and allow a small amount
of oil to leak from the oil filter (this allows air to
be purged from the oil filter and supply hose from
the hydraulic reservoir). Turn filter clockwise
until rubber seal contacts the filter adapter. Then
tighten the filter an additional 2/3 to 3/4 turn.
6. Raise the rear of machine up and support with
jack stands (or equivalent support) just high
enough to allow drive wheels to turn freely.
7. If either drive wheel does not rotate, one or both
of the charge pumps (located on the top of the
main pump as shown in Figure 13) may have lost
their “prime”. Refer to Hydraulic System Air
Purge section.
Note: Do Not change hydraulic system oil (except
for what can be drained when changing filter), unless
it is felt the oil has been contaminated or been
extremely hot.
Changing oil unnecessarily could damage hydraulic
system by introducing contaminates into the system.
Hydraulic System Air Purge
Service Interval: As required
Air must be purged from the hydraulic system
when any hydraulic components, including oil
filter, are removed or any of the hydraulic lines are
disconnected.
The critical area for purging air from the hydraulic
system is between the oil reservoir and each
charge pump located on the top of each variable
displacement pump (Figure 13). Air in other parts of
the hydraulic system will be purged through normal
operation once the charge pump is “primed”.
Figure 13
1. Charge pump cap 2. Loosen 1 1/2 turns only
1. Stop engine and wait for all moving parts to stop.
Raise the rear of the machine up onto jack stands
high enough to raise the drive wheels off the
ground.
2. Check oil level as stated in Check Hydraulic Oil
Level section.
3. Start engine and move throttle control ahead to
full throttle position. Move the speed control
lever to the middle speed position and place the
drive levers in the “drive” position.
If either drive wheel does not rotate, it is possible
to assist the purging of the charge pump by
carefully rotating the tire in the forward position.
Note: It is necessary to lightly touch the charge
pump cap with your hand to check the pump
temperature. If the cap is too hot to touch, turn
off engine. The pumps may be damaged if the
pump becomes too hot.
If either drive wheel still does not rotate continue
with step 4.
4. Thoroughly clean the area around each of the
charge pump housings.
5. To “prime” charge pump, loosen two hex socket
head capscrews (shown in Figure 13) 1 1/2 turns
only. Make sure engine is not running. Lift
the charge pump housing upward and wait for
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