Cub Cadet ST432 manual 6

MAINTENANCE AND REPAIR INSTRUCTIONS

MAINTENANCE AND REPAIR INSTRUCTIONS

CARBURETOR ADJUSTMENT Idle Ajustment Screw

The idle speed of the engine is adjustable. An idle adjustment screw is between the air filter cover and the engine starter housing (Fig. 31).

NOTE: Careless adjustments can seriously damage your unit. An authorized service dealer should make carburetor adjustments.

Check Fuel

Old fuel is usually the reason for improper unit performance. Drain and refill the tank with fresh fuel prior to making any adjustments. Refer to Oil and Fuel Information.

Clean Air Filter	Fig. 31
The condition of the air filter is important to the operation of the	Remove Screws

WARNING: Do not sand blast, scrape or clean electrodes. Grit in the engine could damage the cylinder.

3.Replace cracked, fouled or dirty spark plug. Set the air gap at 0.025 in. (0.635 mm) using a feeler gauge (Fig. 37).

4.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.

SPARK ARRESTOR MAINTENANCE

1.Remove the engine cover. See Rocker Arm Clearance.

0.025 in.

(0.635 mm.)

Fig. 37

unit. A dirty air filter will restrict air flow. This is often mistaken for
an out of adjustment carburetor. Check the condition of the air
filter before adjusting the idle speed screw. Refer to Air Filter
Maintenance.
Adjust Idle Speed Screw
	WARNING: The cutting attachment may spin
	during idle speed adjustments. Wear protective
	clothing and observe all safety instructions to
	prevent serious personal injury.	Fig. 32
If, after checking the fuel and cleaning the air filter, the engine still
will not idle, adjust the idle speed screw as follows:		Engine
1.	Start the engine and let it run at a high idle for a minute to
		Cover
	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 or flat blade screwdriver
	into the hole in the air filter/muffler cover (Fig. 31). Turn the
	idle speed screw in, clockwise, 1/8 of a turn at a time (as	Muffler
	needed) until the engine idles smoothly.
NOTE:	The cutting attachment should not rotate when the
	engine idles.	Fig. 33
3.	If the cutting attachment rotates when the engine idles, turn
		Screw
	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	Rocker Arm Cover
speed should solve most engine problems. If not and all of the	Spark Plug
following are true:
• the engine will not idle	Hole

2.With a flat blade screwdriver or Torx T-20 bit and a T-25 bit, remove the screws attaching the spark arrestor diverter to the muffler (Fig. 38).

3.	Pull the tab on the spark arrestor cover out of the muffler.	Muffler	Spark Arrestor
	Remove the spark arrestor cover.		Screen
4.	Remove the spark arrestor screen from the spark arrestor cover.		Diverter

5. Clean the spark arrestor screen with a wire brush or replace it.

6.	Reinstall the spark arrestor screen, spark arrestor cover and screw.	T-25
		Screw
CLEANING
	WARNING: To avoid serious personal injury,	Slot T-20 Screw
	always turn the unit off and allow it to cool
	before you clean or service it.	Fig. 38

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.

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 60 days. Dispose of the old gasoline in accordance to 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

•the engine hesitates or stalls on acceleration

•there is a loss of engine power

Have the carburetor adjusted by an authorized service dealer.

ROCKER ARM CLEARANCE

WARNING: To avoid serious personal injury, always turn the unit off and allow it to cool before you clean or service it.

This requires disassembly of the engine. If you feel unsure or unqualified to perform this, take the unit to an authorized service center.

NOTE: Inspect the valve to rocker arm clearance with a feeler gauge after the first 25 hours of operation and then every 25 hours of operation thereafter.

•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 two (2) screws on back of the engine cover and the one on the front of the engine cover with a Flat-head or T-25 Torx screwdriver (Fig. 32).

2.Remove the engine cover (Fig. 33).

3.Disconnect the spark plug wire.

4.Clean dirt from around the spark plug. Remove the spark plug from the cylinder head by turning a 5/8 in. socket counterclockwise.

Fig. 34

Adjusting Nuts

INTAKE

Rocker Arms EXHAUST

Fig. 35
Exhaust	Rocker Arm
Adjusting Nut
	Feeler
	Gauge
0.003–0.006 in.
(0.076–0.152 mm)
	Valve Stem
Fig. 36

	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 to 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.

TRANSPORTING

•Allow the engine to cool before transporting.

•Secure the unit while transporting.

•Drain the gas tank before transporting.

•Tighten gas cap before transporting.

	TROUBLESHOOTING
ENGINE WILL NOT START
CAUSE	ACTION
Empty fuel tank	Fill fuel tank with fuel
Primer bulb wasn't pressed enough	Press primer bulb fully and slowly 10 times

5.Clean dirt from around the rocker arm cover. Remove the

screw holding the rocker arm cover with a large flat blade screwdriver or Torx T-25 bit (Fig. 34). Remove the rocker arm cover and gasket.

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. 34)

•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. 36). 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. Figure 35 and 36 show how to measure the clearance.

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. 36).

•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).

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 753-05255spark plug. The correct air gap is 0.025 in. (0.635 mm). Remove the plug after every 25 hours of operation and check its condition.

1.Stop the engine and allow it to cool. Remove the two (2) screws on back of the engine cover and the one on the front of the engine cover with a Flat-head or T-25 Torx screwdriver (Fig. 32).

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 counterclockwise.

Old fuel	Drain gas tank and add fresh fuel
Fouled spark plug	Replace or clean the spark plug
Plugged spark arrestor	Clean or replace spark arrestor
ENGINE WILL NOT IDLE
CAUSE	ACTION
Air filter is plugged	Replace or clean the air filter
Old fuel	Drain gas tank and add fresh fuel
Improper carburetor adjustment	Adjust according to the Carburetor Adjustments
	section or take to an authorized service dealer
	for an adjustment
ENGINE WILL NOT ACCELERATE
CAUSE	ACTION
Old fuel	Drain gas tank and add fresh fuel
	Adjust according to the Carburetor Adjustments
Improper carburetor adjustment	section or take to an authorized service dealer
	for an adjustment
Cutting attachment bound with grass	Stop the engine and clean the cutting attachment
Dirty air filter	Clean or replace the air filter
Plugged spark arrestor	Clean or replace spark arrestor

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