Ariens HVZ 915085-2350 Service Manual download pdf (Page 25)

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7.3 HYDRO-GEAR FLUID

RECOMMENDATIONS

The fluids used in Hydro-Gear transaxles have been

carefully selected, and only equivalent or better

products should be used.

Typically, an engine oil with a minimum rating of 55 sus

at 210

F and an API classification of SH/CD is

recommended. A 20W-50 engine oil has been selected

for use by the factory. Fluid volume is 54.1 fluid oz

(1600 ml) to 57.5 fl oz (1700 ml).

7.4 FLUID VOLUME AND LEVEL

Certain situations may require additional fluid to be

added or even replaced. See transmission

manufacturer’s manual for proper fill port location.

Fill the unit so the oil level is 0.75”-1.50” (19-38 mm)

below the oil fill port.

Recheck the fluid level once the unit has been

operated for approximately 1 minute.

Purging will be required. See Purging Procedure in this

section.

NOTE: Any servicing dealer attempting a warranty

repair must have prior approval before conducting

maintenance of a Hydro-Gear product unless the ser-

vicing dealer is current Authorized Hydro-Gear Service

Center.

7.5 CHANGING FLUID

The transaxle has been filled with oil and sealed at the

factory. It should not require oil maintenance. However,

if the oil becomes contaminated or degrades, adding or

changing oil may alleviate certain performance

problems as listed in the Hydro Transmission

Troubleshooting.

1. Remove the transaxle from the vehicle (see Hydro-

gear Transmission Removal for procedure).

2. Clean the oil fill port area of any debris.

3. Remove the oil fill port fitting (see transmission

manufacturer’s manual for fill port location).

4. Position the transaxle so the oil will drain

completely out of the housing.

5. Fill the transaxle at the oil fill port.

6. Install the oil fill port fitting.

7. Purging will be required (see Purging Procedure in

this section).

8. Recheck the fluid level once the unit has been

operated for approximately 1 minute.

7.6 PURGING PROCEDURE

Because air reduces the efficiency of hydrostatic

drives, purging air from the system is critical. Air

creates inefficiency because its compression and

expansion rate is higher than that of the oil approved

for use in hydrostatic drive systems. The resulting

symptoms in hydrostatic systems may be:

• Noisy operation.

• Lack of power or drive after short term operation.

• High operation temperature and excessive

expansion of oil.

These purge procedures should be implemented any

time a the drive system has been opened for

maintenance or adding oil.

Before starting, make sure the transaxle/transmission

is at the proper oil level. If it is not, fill to the

specifications outlined in Sections 7.3. and 7.4.

The following procedures should be performed with the

vehicle drive wheels off the ground, then repeated

under normal operating conditions.

1. Open bypass valve.

2. Start engine.

3. Slowly move the directional control levers in both

forward and reverse directions (5 or 6 times). As air

is purged from the unit, the oil level will drop.

4. Close the bypass valve. Do not stop engine.

5. Slowly move the directional control levers in both

forward and reverse directions (5 to 6 times).

6. Stop engine.

7. Check the oil level, and add oil as required.

If necessary, repeat the preceding steps until all

the air is completely purged from the system.

When the transaxle moves forward and reverse at

normal speed purging is complete.

Knocking Control linkage bent or out of adjustment Repair or replace linkage

Oil level low Fill to proper level

Contaminated or incorrect oil Change oil

Air trapped in hydraulic system Purge hydraulic system

Bypass assembly sticking Repair or replace bypass

Metallic pieces or foreign objects in unit Repair or replace transmission

Loose parts Repair or replace loose parts

TRANSMISSION TROUBLESHOOTING

Problem Possible Cause Corrective Action

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Ariens HVZ 915085-2350 Service Manual Page 25

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