Maintenance & Repair Instructions; Cleaning And Storage; Troubleshooting Chart; Specifications - Cub Cadet ST4175 Operator's Manual

4-cycle trimmer
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MAINTENANCE AND REPAIR INSTRUCTIONS
MAINTENANCE SCHEDULE
WARNING:
To prevent serious injury, never perform maintenance or repairs with unit running. Always
service and repair a cool unit. Disconnect the spark plug wire to ensure that the unit cannot start.
Perform these required maintenance procedures at the frequency stated in the table. These procedures should also be
a part of any seasonal tune-up.
NOTE:
Some maintenance procedures may require special tools or skills. If you are unsure about these procedures
take your unit to any non-road engine repair establishment, individual or authorized service dealer.
NOTE:
Maintenance, replacement, or repair of the emission control devices and system may be performed by any
non-road engine repair establishment, individual or authorized service dealer.
NOTE:
Please read the California/EPA statement that came with the unit for a complete listing of terms and
coverage for the emissions control devices, such as the spark arrestor, muffler, carburetor, etc.
FREQUENCY
MAINTENANCE REQUIRED
Every 10 hours
Clean and oil air filter
Change 1st 10 hours
Change oil
Change oil
Every 25 hours
Check rocker arm to valve clearance and adjust
Check spark plug condition and gap
FIXED LINE INSTALLATION
WARNING:
Never use metal-reinforced line, wire, chain or rope. These can break off and become
dangerous projectiles.
Always use original equipment manufacturer 0.105
inch (2.67 mm) replacement line. Lines other than
those specified may make the engine overheat or fail.
To install the trimming line:
1. Insert each end of the replacement line into the
holes on either side of retention hook (Fig. 15).
2. Push the ends through until they stick out of
the sides of the head (Fig. 16).
3. Pull the ends through making sure that the
ends are of equal length and the middle of the
line is centered between the insertion holes
(Fig. 17).
4. If the ends are not of equal length, push the
longer end back through the head part way and
pull the shorter end to compensate. Repeat
until both ends are the same length.
5. Push the trimmer line until it lies flat against the
cutting head (Fig. 18). Make sure the two
lengths of cutting line are of equal length. If
they are not, adjust until they are.
WARNING:
Always use the correct line length when installing trimming line on the unit. The line may not
release properly if the line is too long.
CHECKING THE OIL LEVEL
WARNING:
To prevent extensive engine wear and damage to the unit, always maintain the proper oil
level in the crankcase. Never operate the unit with a low oil level.
The importance of checking and maintaining the
proper oil level in the crankcase cannot be
overemphasized. Check oil before each use:
1. Stop the engine and allow oil to drain into the
crankcase.
2. Place the unit on a flat, level surface to get a
proper oil level reading (Fig. 22).
3. Keep dirt, grass clippings and other debris out
of the engine. Clean the area around the
dipstick before removing it.
4. Remove the oil fill plug/dipstick and wipe off oil. Reinsert it all the way back in. (Fig. 20)
5. Remove the oil fill plug/ dipstick and check the oil level. Oil should be up to the top of the dipstick (Fig. 19).
6. If the level is low, add a small amount of oil to the oil fill hole and recheck (Fig. 20). Repeat this procedure until the
oil level reaches the top of the dipstick.
NOTE:
Do not overfill the unit.
NOTE:
Make sure the O-ring is in place on the oil fill plug/ dipstick when checking and changing the oil (Fig. 19).
CHANGING THE OIL
CAUTION:
Wear gloves to prevent injury when handling the unit.
Change the oil while the engine is still warm. The
oil will flow freely and carry away more impurities.
1. Unplug spark plug boot to prevent accidental
starting.
2. Remove the oil fill plug/dipstick.
3. Pour the oil out of the oil fill hole and into a
container by tipping the unit to a vertical position
(Fig. 21). Allow ample time for complete drainage.
4. Wipe up any oil residue on the unit and clean
up any oil that may have spilled. Dispose of the
oil according to federal, state and local regulations.
5. Refill the crankcase with 3.04 fl.oz. (90 ml) of SAE 30 SF, SG, SH oil.
NOTE:
Use the bottle and spout saved from initial use to measure the correct
amount of oil. The top of the label on the bottle measures approximately
3.04 ounces (90 ml) (Fig. 23). Check the level with the dipstick. If the level
is low, add a small amount of oil and recheck. Do not overfill (Fig. 20).
6. Replace the oil fill plug/dipstick.
7. Reconnect the spark plug boot.
AIR FILTER MAINTENANCE
Cleaning the Air Filter
Failure to maintain your air filter properly can result in poor performance or can cause
permanent damage to your engine.
1. Open the air filter cover. Push the tab on the left side of the cover inward. Then
pull the air filter cover out and to the right (Fig. 24).
NOTE:
It may be necessary to remove the fuel cap to completely remove the air
filter cover.
2. Remove the air filter (Fig. 24).
3. Wash the filter in detergent and water. Rinse the filter thoroughly and allow it to dry.
4. Apply enough clean SAE 30 motor oil to lightly coat the filter.
5. Squeeze the filter to spread and remove excess oil.
6. Replace the filter (Fig. 24).
NOTE:
If the unit is operated without the air filter, you will VOID the warranty.
7. Reinstall the air filter cover. Position the hooks on the right side of the air filter cover into the slots at the right side
of the back plate (Fig. 24).
NOTE:
It may be necessary to remove the fuel cap to completely replace the air filter cover.
8. Swing the cover to the left until the tab on the air filter cover snaps into place in the slot on the back plate (Fig. 24).
9. Replace the fuel cap if you have removed it.
IDLE SPEED ADJUSTMENT
WARNING:
The cutting attachment may spin during idle speed adjustments. Wear protective clothing
and observe all safety instructions to prevent serious personal injury.
The idle speed of the engine is adjustable. An idle adjustment screw is between the
air filter cover and the engine starter housing (Fig. 25).
NOTE:
Careless adjustments can seriously damage your unit. An authorized
service dealer should make carburetor adjustments.
If, after checking the fuel and cleaning the air filter, the engine still will not idle, adjust
the idle speed screw as follows:
1. Start the engine and let it run at a high idle for a minute to warm up. Refer to
Starting/Stopping Instructions.
2. Release the throttle trigger and let the engine idle. If the engine stops, insert a
small Phillips screwdriver in between the Air Filter Cover and the Engine Cover
(Fig. 25). Turn the idle speed screw in, clockwise, 1/8 of a turn at a time (as needed) until the engine idles smoothly.
NOTE:
The cutting attachment should not rotate when the engine idles.
3. If the cutting attachment rotates when the engine idles, turn the idle speed screw counterclockwise 1/8 of a turn at
a time (as needed), to reduce idle speed.
Checking the fuel, cleaning the air filter, and adjusting the idle speed should solve most engine problems. If not and all
of the following are true:
• the engine will not idle
• the engine hesitates or stalls on acceleration
• there is a loss of engine power
Have the carburetor adjusted by an authorized service dealer.
4
Fig. 15
Fig. 17
Oil Fill Plug/ Dipstick
Oil Fill
Plug
O-Ring
Full
Add 1.4-
1.5 oz.
O-Ring
(41-44 ml)
Oil Fill
Hole
Fig. 19
Fig. 20
Fig. 21
Fig. 22
Fill Line
Fig. 23
Air Filter
Fig. 24
Idle Adjustment Screw
Fig. 25
ROCKER ARM CLEARANCE
This service requires disassembly of the engine. If
feeling unsure or unqualified to perform this service,
take the unit to an authorized service center.
• The engine must be cold when checking or
adjusting the valve clearance.
• This task should be performed inside, in a clean,
dust free area.
1. Remove the five (5) screws with a Flat-head or
T-20 Torx screwdriver and the one T-25 screw
(Fig. 26).
2. Disconnect the spark plug wire.
3. Clean dirt from around the spark plug. Remove
the spark plug from the cylinder head by
SEE
turning a 5/8 in. socket counterclockwise.
4. Remove the engine cover (Fig. 26).
p. 4
5. Clean dirt from around the rocker arm cover.
p. 4
Remove the screw holding the rocker arm
cover with a large flat blade screwdriver or Torx
p. 4
T-25 bit (Fig. 27). Remove the rocker arm cover
p. 4
and gasket.
p. 4
6. Pull the starter rope slowly to bring the piston to the top of its travel, (known as top dead center). Check that:
• The piston is at the top of its travel while looking in the spark plug hole (Fig. 27).
• Both rocker arms move freely, and both valves are closed.
If these statements are not true, repeat this step.
7. Slide the feeler gauge between the rocker arm and the valve return spring. Measure the clearance between the
valve stem and rocker arm (Fig. 28). Measure both the intake and exhaust valves.
The recommended clearance for both intake and exhaust is .003 – .006 in. (.076 – 0.152 mm). Use a standard
automotive .005 in. (0.127 mm) feeler gauge. The feeler gauge should slide between the rocker arm and valve stem
with a slight amount of resistance, without binding. See Figures 28 and 29.
8. If the clearance is not within specification:
a. Turn the adjusting nut using a 5/16 inch (8 mm) wrench or nut driver (Fig. 29).
• To increase clearance, turn the adjusting nut counterclockwise.
• To decrease clearance, turn the adjusting nut clockwise.
b. Recheck both clearances and adjust as necessary.
9. Reinstall the rocker arm cover using a new gasket. Torque the screw to 20–30 in•lb (2.2–3.4 N•m).
Fig. 16
10. Check the spark plug and reinstall. See Replacing the Spark Plug.
11. Replace the spark plug wire.
12. Reinstall the engine cover. Check alignment of the cover before tightening the screws. Tighten screws.
REPLACING THE SPARK PLUG
Use a replacement part number 791-180852 spark plug. The correct air gap is 0.025 in. (0.635 mm).
1. Stop the engine and allow it to cool. Remove the five (5) screws with a Flat-head or T-20 Torx screwdriver and the
one T-25 screw (Fig. 26).
2. Grasp the plug wire firmly and pull the cap from the spark plug.
3. Clean dirt from around the spark plug. Remove the spark plug from the cylinder head by turning a 5/8 in. socket
Fig. 18
counterclockwise.
WARNING: Do not sand blast, scrape or clean electrodes. Grit in the
engine could damage the cylinder.
4. Replace cracked, fouled or dirty spark plug. Set the air gap at 0.025 in. (0.635 mm.)
using a feeler gauge (Fig. 30).
5. Install a correctly-gapped spark plug in the cylinder head. Turn the 5/8 in. socket
clockwise until snug.
If using a torque wrench torque to: 110-120 in.•lb. (12.3-13.5 N•m)
Do not over tighten.
CLEANING
WARNING:
cleaning or servicing it.
Use a small brush to clean off the outside of the unit. Do not use strong detergents. Household cleaners that contain
aromatic oils such as pine and lemon, and solvents such as kerosene, can damage plastic housing or handle. Wipe off
any moisture with a soft cloth.
STORAGE
• Never store the unit with fuel in the tank where fumes may reach an open flame or spark.
• Allow the engine to cool before storing.
• Lock up the unit to prevent unauthorized use or damage.
• Store the unit in a dry, well-ventilated area.
• Store the unit out of the reach of children.
Short Term Storage (1-2 weeks)
1. Store the unit in a horizontal position. If this is not possible, store the unit vertically with the engine at the top.
Long Term Storage
1. Drain all gasoline from the gas tank into a container. Do not use gas that has been stored for more than 30 days.
Dispose of the old gasoline in accordance with federal, state and local regulations.
2. Start the engine and allow it to run until it stalls. This ensures that all gasoline has been drained from the carburetor.
3. Allow the engine to cool. Remove the spark plug and put 5 drops of high quality motor oil into the cylinder. Pull the
starter rope slowly to distribute the oil. Reinstall the spark plug.
NOTE:
Remove the spark plug and drain all of the oil from the cylinder before attempting to start the trimmer after
storage.
4. Change the oil, referring to Changing the Oil. Dispose of the old oil in accordance with federal, state and local regulations.
5. Thoroughly clean the unit and inspect for any loose or damaged parts. Repair or replace damaged parts and
tighten loose screws, nuts or bolts. The unit is ready for storage.
CAUSE
ENGINE WILL NOT START
Empty fuel tank
Primer bulb wasn't pressed enough
Old fuel (over 30 days)
Fouled spark plug
Air Filter Cover
ENGINE WILL NOT IDLE
Air filter is plugged
Old fuel (over 30 days)
Improper idle speed
Tab
ENGINE WILL NOT ACCELERATE
Old fuel (over 30 days)
Cutting attachment bound with grass
Dirty air filter
ENGINE LACKS POWER OR STALLS WHEN CUTTING
Old fuel (over 30 days)
Fouled spark plug
If further assistance is required, contact an authorized service dealer.
UNIT*
Engine Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air-Cooled, 4-Cycle
Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 cu. in. (26.2 cc)
Clutch Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Centrifugal
Operating RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,200+ rpm
Idle Speed RPM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,800 - 3,600 rpm
Valve clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.003–0.006 in. (0.076–0.152 mm)
Spark Plug Gap. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.025 inch (0.635 mm)
Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAE 30 Oil
Crankcase Oil Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.04 oz (90 ml)
Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Unleaded
Fuel Tank Capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 oz (532 ml)
Approximate Unit Weight (No fuel, with handle, shield and cutting attachment) . . . . . . . . . . . . . . . . . . . 14.5 lbs (6.5 kg)
Trimming Line Diameter: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.105 inches (2.67 mm)
Cutting Path Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 in. (43.18 cm.)
*All specifications are based on the latest product information available at the time of printing. We reserve the right to
make changes at any time without notice.
MAINTENANCE AND REPAIR INSTRUCTIONS
View Of The Rear Engine Cover
Screws
T-25 Screws
Fig. 26
Adjustment
Rocker
Intake
Arms
Fig. 28
To avoid serious personal injury, always turn the unit off and allow it to cool before
TROUBLESHOOTING
ACTION
Fill fuel tank with fuel
Press primer bulb fully and slowly 10 times
Drain fuel tank and add fresh fuel
Replace or clean the spark plug
Replace or clean the air filter
Drain fuel tank and add fresh fuel
Adjust according to the Idle Speed Adjustment section
Drain fuel tank and add fresh fuel
Stop the engine and clean the cutting attachment
Clean or replace the air filter
Drain fuel tank and add fresh fuel
Replace or clean the spark plug

SPECIFICATIONS

Rocker Arm
Cover
Screws
Spark
Plug Hole
Fig. 27
Nuts
Feeler
Gauge
0.003–0.006 in.
(0.076–0.152 mm)
Exhaust
Valve Stem
Fig. 29
0.025 in.
(0.635 mm.)
Fig. 30

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