MTD 663, 643 User Manual
OPERATOR’S MANUAL
Snow Thrower
Models
643 & 663
IMPORTANT: READ SAFETY RULES AND INSTRUCTIONS CAREFULLY
Warning: This unit is equipped with an internal combustion engine and should not be used on or near any unimproved forest-
covered, brush-covered or grass-covered land unless the engine’s exhaust system is equipped with a spark arrester meeting
applicable local or state laws (if any). If a spark arrester is used, it should be maintained in effective working order by the operator.
In the State of California the above is required by law (Section 4442 of the California Public Resources Code). Other states may have
similar laws. Federal laws apply on federal lands. A spark arrester for the muffler is available through your nearest engine authorized
service dealer or contact the service department, P.O. Box 361131 Cleveland, Ohio 44136-0019.
MTD LLC P.O. BOX 361131 CLEVELAND, OHIO 44136-0019
PRINTED IN U.S.A.
FORM NO.
769-00377.fm
(6/02)
TABLE OF CONTENTS
Content Page
Important Safe Operation Practices...................................................................3
Assembling Your Snow Thrower ....................................................................... 5
Know Your Snow Thrower.................................................................................6
Operating Your Snow Thrower ..........................................................................7
Making Adjustments ..........................................................................................10
Maintaining Your Snow Thrower........................................................................12
Servicing Your Snow Thrower ........................................................................... 13
Troubleshooting................................................................................................. 16
Parts List............................................................................................................17
FINDING MODEL NUMBER
This Operator’s Manual is an important part of your new Snow Thrower. It will help you assemble, prepare
and maintain the unit for best performance. Please read and understand what it says.
Before you start assembling your new equipment, please locate the model plate on the
equipment and copy the information from it in the space provided below. The information on
the model plate is very important if you need help from your local authorized dealer.
You can locate the model number by looking at the lower frame cover on the rear of your snow thrower. A
sample model plate is explained below. For future reference, please copy the model number and the serial
number of the equipment in the space below.
Copy the model number here:
MTD LLC
www.mtdproducts.com
P. O. BOX
CLEVELAND,OH
330-220-4683
800-800-7310
361131
44136
Copy the serial number here:
ENGINE INFORMATION
The engine manufacturer is responsible for all engine-related issues with regards to performance, powerrating, specifications, warranty and service. Please refer to the engine manufacturer’s Owner’s/Operator’s
Manual packed separately with your unit for more information.
CALLING CUSTOMER SUPPORT
Please do NOT return the unit to the retailer from which it was purchased, without first contacting Customer Support.
Should you have difficulty assembling this product or have any questions regarding the controls, operation
or maintenance of this unit, please call the Customer Support Department.
Call 1- (330) 220-4MTD (4683) or 1- (800)-800-7310 to reach a Customer Support
representative. Please have your unit’s model number and serial number ready when you
call. See previous section to locate this information. You will be asked to enter the serial
number in order to process your call.
For more details about your unit, visit our website at www.mtdproducts.com
2
SECTION 1: IMPORTANT SAFE OPERATION PRACTICES
This symbol points out important safety instructions, which if not followed, could endanger the personal
safety and/or property of yourself and others. Read and follow all instructions in this manual before
attempting to operate this machine. Failure to comply with these instructions may result in personal
injury. When you see this symbol—heed its warning.
WARNING:
Engine Exhaust, some of its constituents, and certain vehicle components contain
or emit chemicals known to the State of California to cause cancer, birth defects or other
reproductive harm
.
DANGER: This machine was built to be operated according to the rules for safe operation in this
manual. As with any type of power equipment, carelessness or error on the part of the operator can
result in serious injury. This machine is capable of amputating hands and feet and throwing objects.
Failure to observe the following safety instructions could result in serious injury or death.
TRAINING
1. Read, understand, and follow all instructions on the
machine and in the manual(s) before attempting to
assemble and operate. Keep this manual in a safe place
for future and regular reference and for ordering
replacement parts.
2. Be familiar with all controls and their proper operation.
Know how to stop the machine and disengage them
quickly.
3. Never allow children under 14 years old to operate this
machine. Children 14 years old and over should read and
understand the operation instructions and safety rules in
this manual and should be trained and supervised by a
parent.
4. Never allow adults to operate this machine without proper
instruction.
5. Thrown objects can cause serious personal injury. Plan
your snow-throwing pattern to avoid discharge of material
toward roads, bystanders and the like.
6. Keep bystanders, helpers, pets and children at least 75
feet from the machine while it is in operation. Stop
machine if anyone enters the area.
7. Exercise caution to avoid slipping or falling, especially
when operating in reverse.
PREPARATION
1. Thoroughly inspect the area where the equipment is to be
used. Remove all doormats, newspapers, sleds, boards,
wires and other foreign objects, which could be tripped
over or thrown by the auger/impeller.
2. Always wear safety glasses or eye shields during
operation and while performing an adjustment or repair to
protect your eyes. Thrown objects which ricochet can
cause serious injury to the eyes.
3. Do not operate without wearing adequate winter outer
garments. Do not wear jewelry, long scarves or other
loose clothing, which could become entangled in moving
parts. Wear footwear which will improve footing on
slippery surfaces.
4. Use a grounded three-wire extension cord and
receptacle for all units with electric start engines.
5. Adjust collector housing height to clear gravel or crushed
rock surfaces.
6. Disengage all clutch levers before starting the engine.
7. Never attempt to make any adjustments while engine is
running, except where specifically recommended in the
operator’s manual.
8. Let engine and machine adjust to outdoor temperature
before starting to clear snow.
9. To avoid personal injury or property damage use extreme
care in handling gasoline. Gasoline is extremely
flammable and the vapors are explosive. Serious
personal injury can occur when gasoline is spilled on
yourself or your clothes, which can ignite. Wash your skin
and change clothes immediately.
a. Use only an approved gasoline container.
b. Extinguish all cigarettes, cigars, pipes and other
sources of ignition.
c. Never fuel machine indoors.
d. Never remove gas cap or add fuel while the
engine is hot or running.
e. Allow engine to cool at least two minutes before
refueling.
f. Never over fill fuel tank. Fill tank to no more than ½
inch below bottom of filler neck to provide space
for fuel expansion.
g. Replace gasoline cap and tighten securely.
h. If gasoline is spilled, wipe it off the engine and
equipment. Move machine to another area. Wait 5
minutes before starting the engine.
i. Never store the machine or fuel container inside
where there is an open flame, spark or pilot light
(e.g. furnace, water heater, space heater, clothes
dryer etc.).
j. Allow machine to cool at least 5 minutes before
storing.
OPERATION
1. Do not put hands or feet near rotating parts, in the auger/
impeller housing or discharge chute. Contact with the
rotating parts can amputate hands and feet.
2. The auger/impeller clutch lever is a safety device. Never
bypass its operation. Doing so makes the machine
unsafe and may cause personal injury.
3. The clutch levers must operate easily in both directions
and automatically return to the disengaged position when
released.
3
4. Never operate with a missing or damaged discharge
chute. Keep all safety devices in place and working.
5. Never run an engine indoors or in a poorly ventilated
area. Engine exhaust contains carbon monoxide, an
odorless and deadly gas.
6. Do not operate machine while under the influence of
alcohol or drugs.
7. Muffler and engine become hot and can cause a burn. Do
not touch.
8. Exercise extreme caution when operating on or crossing
gravel surfaces. Stay alert for hidden hazards or traffic.
9. Exercise caution when changing direction and while
operating on slopes.
10. Plan your snow-throwing pattern to avoid discharge
towards windows, walls, cars etc. Thus, avoiding
possible property damage or personal injury caused by a
ricochet.
11. Never direct discharge at children, bystanders and pets
or allow anyone in front of the machine.
12. Do not overload machine capacity by attempting to clear
snow at too fast of a rate.
13. Never operate this machine without good visibility or
light. Always be sure of your footing and keep a firm hold
on the handles. Walk, never run.
14. Disengage power to the auger/impeller when
transporting or not in use.
15. Never operate machine at high transport speeds on
slippery surfaces. Look down and behind and use care
when in reverse.
16. If the machine should start to vibrate abnormally, stop the
engine, disconnect the spark plug wire and ground it
against the engine. Inspect thoroughly for damage.
Repair any damage before starting and operating.
17. Disengage all clutch levers and stop engine before you
leave the operating position (behind the handles). Wait
until the auger/impeller comes to a complete stop before
unclogging the discharge chute, making any
adjustments, or inspections.
18. Never put your hand in the discharge or collector
openings. Always use the clean-out tool provided to
unclog the discharge opening. Do not unclog discharge
chute while engine is running.Shut off engine and remain
behind handles until all moving parts have stopped
before unclogging.
19. Use only attachments and accessories approved by the
manufacturer (e.g. wheel weights, tire chains, cabs etc.).
20. If situations occur which are not covered in this manual,
use care and good judgment. Contact your dealer or
telephone 1-800-800-7310 for assistance and the name
of your nearest servicing dealer.
MAINTENANCE AND STORAGE
1. Never tamper with safety devices. Check their proper
operation regularly. Refer to the maintenance and
adjustment sections of this manual.
2. Before cleaning, repairing, or inspecting machine
disengage all clutch levers and stop engine. Wait until the
auger/impeller come to a complete stop. Disconnect the
spark plug wire and ground against the engine to prevent
unintended starting.
3. Check bolts and screws for proper tightness at frequent
intervals to keep the machine in safe working condition.
Also, visually inspect machine for any damage.
4. Do not change the engine governor setting or over-speed
the engine. The governor controls the maximum safe
operating speed of the engine.
5. Snow thrower shave plates and skid shoes are subject to
wear and damage. For your safety protection, frequently
check all components and replace with original
equipment manufacturer’s (OEM) parts only. “Use of
parts which do not meet the original equipment
specifications may lead to improper performance and
compromise safety!”
6. Check clutch controls periodically to verify they engage
and disengage properly and adjust, if necessary. Refer to
the adjustment section in this operator’s manual for
instructions.
7. Maintain or replace safety and instruction labels, as
necessary.
8. Observe proper disposal laws and regulations for gas,
oil, etc. to protect the environment.
9. Prior to storing, run machine a few minutes to clear snow
from machine and prevent freeze up of auger/impeller.
10. Never store the machine or fuel container inside where
there is an open flame, spark or pilot light such as a water
heater, furnace, clothes dryer etc.
11. Always refer to the operator’s manual for proper
instructions on off-season storage.
WARNING: Restrict the use of this power
machine to persons who read, understand
and follow the warnings and instructions
in this manual and on the machine.
4
SECTION 2: ASSEMBLING YOUR SNOW THROWER
NOTE: References to right or left side of the snow
thrower are determined from behind the unit in the
operating position. The “operator’s position” is defined
as standing directly behind the snow thrower, facing the
handle panel.
Unpacking
• Remove screws from the top sides and ends of the
shipping crate.
• Set panel aside to avoid tire punctures or personal
injury.
• Remove and discard plastic bag that covers unit.
• Remove any loose parts included with unit (i.e.,
Operator’s Manual, etc).
• Roll unit out of crate.
Loose Parts
The augers are secured to the auger shaft with two
shear bolts and hex lock nuts. If you hit a foreign object
or ice jam, the snow thrower is designed so that the
bolts may shear. Two replacement shear bolts and nuts
are provided for your convenience. Store in a safe
place until needed. See Figure 1.
Shear Bolts
Hex Lock
Nuts
• Raise the upper handle assembly until it locks over
the lower handle.
• Look at the lower rear of the snow thrower frame to
be sure all the cables are aligned with the cable
roller guides.
• Secure the upper handle and lower handle with the
two plastic wing nuts, cupped washers and carriage
bolts previously removed and tighten the upper two
plastic wing nuts. See Figure 3.
Upper
Shift Rod
Shift Rod
Connector
Lower
Shift Rod
Wing Nuts
Figure 3
• Slide the shift rod connector down over the end of
the lower shift rod. Tap the connector until it locks
over the lower shift rod. See Figure 3.
Figure 1
Assembly
WARNING: Disconnect the spark plug
wire and ground it against the engine to
prevent unintended starting.
• Remove the lower two plastic wing nuts, cupped
washers and carriage bolts from each side of the
lower handle. See Figure 2.
Lower
Handle
Wing Nuts,
Washers, & Bolts
Figure 2
Handle
Panel
Upper Handle
NOTE: If the connector is not properly assembled, the
shift rod will pivot and you will not be able to change
speeds or change directions.
• If not already attached, slip the cables that run from
the handle panel to the chute into the cable guide
located on top of the engine. See Figure 4.
Cable Guide
Figure 4
• Unwrap the headlight wire, which is attached to the
headlight beneath the handle panel.
• Wind the headlight wire around the right handle
until excess slack is removed.
• Plug the wire from the headlight into the wire lead
coming from the right side of the engine, beneath
the fuel tank.
5
SECTION 3: KNOW YOUR SNOW THROWER
Traction Control /
Auger Control Lock
Headlight
Discharge
Chute
Auger
WARNING: Read, understand, and follow
all instructions and warnings on the
machine and in this manual before
operating.
Skid Shoe
Figure 5
Traction Control / Auger Control Lock
The traction control is located on the right handle.
Squeeze the traction control to engage the wheel drive.
Release to stop. See Figure 5.
This same lever also locks the auger control so you
can turn the chute directional control without
interrupting the snow throwing process. If the auger
control is engaged along with the traction control, the
operator can release the auger control (on the left
handle) and the augers will remain engaged. Release
the traction control to stop both the augers and track
drive (auger control must also be released).
IMPORTANT:
changing speeds.
Always release tractional control before
Auger Drive Control
The auger drive control is located on the left handle.
Squeeze the control grip to engage the augers.
Release to stop the snow throwing action. (Traction
control must also be released.) See Figure 5.
Skid Shoe
The position of the skid shoe is determined by the
condition of the ground from where snow has to be
removed. See Figure 5.
Shift Lever
Auger Drive Control
Chute Directional
Control
Primer
Choke
Safety
Ignition Key
Throttle
Control
Clean-out
Shift Lever
The shift lever is located in the center of the handle
panel and is used to determine both ground speed and
direction of travel. It can be moved into any of eight
positions. See Figure 5.
Forward
Your snow thrower has six forward (F) speeds. Position
number one (1) is the slowest. Position number six (6)
is the fastest.
Reverse
Your snow thrower has two reverse (R) speeds. R1 is
the slower, while R2 is the faster of the two.
IMPORTANT:
changing speeds.
Always release tractional control before
Chute Directional Control
The chute directional control is located on left side of
the snow thrower. See Figure 5.
To change the direction in which snow is thrown, turn
chute directional control as follows:
• Crank clockwise to discharge to the left.
• Crank counterclockwise to discharge to the right.
Safety Ignition Key
The safety ignition key must be fully inserted in the
switch before the unit will start. Remove the ignition key
when the snow thrower is not in use. See Figure 5.
IMPORTANT:
Do NOT attempt to turn the key.
Tool
Electric
Starter
Button
Switch
Box
Recoil
Starter
Handle
6
Headlight
The headlight is on whenever the engine is running.
designed to clear a clogged discharged chute. Refer to
Operating Your Snow Thrower section for more detailed
information regarding the chute clean-out tool.
See Figure 5.
Throttle Control
The throttle control is located on the engine. It regulates
the speed of the engine and will shut off the engine
when pushed down completely. See Figure 5.
WARNING: Never use your hand to clear a
clogged discharged chute. Shut off
engine and remain behind handles until
all moving parts have stopped before
unclogging.
Clean-Out Tool
The chute clean-out tool is fastened to the top of the
auger housing with a mounting clip. The tool is
SECTION 4: OPERATING YOUR SNOW THROWER
Before Starting
WARNING: Read, understand, and follow
all instructions and warnings on the
machine and in this manual before
operating.
Gas And Oil Fill-up
Service the engine with gasoline and oil as
instructed in the separate engine manual packed with
your snow thrower. Read instructions carefully.
WARNING: Use extreme care when
handling gasoline. Gasoline is extremely
flammable and the vapors are explosive.
Never fuel machine indoors or while the
engine is hot or running. Extinguish
cigarettes, cigars, pipes an other sources
of ignition.
• A plastic cup is provided inside the fuel fill opening
on the fuel tank. Remove and discard this cup
before filling up the tank. Use the separate fuel tank
cap to close after fill-up.
To Start Engine
• Attach spark plug wire to spark plug. Make certain
the metal loop on end of the spark plug wire (inside
the boot) is fastened securely over the metal tip on
the spark plug.
• Make certain the fuel cut-off valve, if your snow
thrower is so equipped, is in OPEN position.
• Make certain the auger and drive clutch levers are
in the disengaged (released) position.
• Move throttle control up to FAST position. Insert
ignition key into slot. Be certain it snaps into place.
Do not turn key.
NOTE: Engine will not start unless ignition key is
inserted into ignition slot in carburetor cover.
Electric Starter
• Determine that your house wiring is a three-wire
grounded system. Ask a licensed electrician if you
are not certain.
• If your house wiring system is not a three-wire
grounded system, do not use this electric starter
under any conditions.
WARNING: The electric starter is
equipped with a grounded three-wire
power cord and plug and is designed to
operate on 120 volt AC household
current. It must be used with a properly
grounded three-prong receptacle at all
times to avoid the possibility of electric
shock. Follow all instructions carefully
prior to operating the electric starter.
• If your home electrical system is grounded, but a
three-hole receptacle is not available, one should
be installed by a licensed electrician before using
the electric starter.
• If you have a grounded three-prong receptacle,
proceed as follows:
• Rotate choke knob to OFF position and do not
prime engine.
• Connect power cord to switch box on engine. Plug
the other end of power cord into a three-hole,
grounded 120 volt AC receptacle.
• Push starter button on top of the engine to crank
engine. As you crank the engine, move choke knob
to FULL choke position.
• When engine starts, release starter button, and
move choke gradually to OFF. If engine falters,
move choke immediately to FULL and then
gradually to OFF.
• When disconnecting the power cord, always unplug
from the three-prong receptacle first and then from
the snow thrower.
7
Recoil Starter
• Rotate choke knob to FULL choke position (cold
engine start). If engine is warm, place choke in OFF
position instead of FULL.
• Push primer button two or three times. If engine is
warm, push primer button once only.
NOTE: Always cover vent hole in primer button when
pushing. Additional priming may be necessary for first
start if temperature is below 15°F.
appropriate for the snow conditions that exist. Use
the slower speeds until you are familiar with the
operation of the snow thrower.
• Squeeze the auger control grip and the augers will
turn. Release it and the augers will stop.
• Squeeze traction control grip and the snow thrower
will move. Release it and drive motion will stop.
• NEVER move shift lever without releasing drive
clutch.
• Grasp starter handle and pull rope out slowly, until
it pulls slightly harder. Let rope rewind slowly.
• Pull starter handle rapidly. Do not allow handle to
snap back. Allow it to rewind slowly while keeping a
firm hold on the starter handle.
• As engine warms up and begins to operate evenly,
rotate choke knob slowly to OFF position. If engine
falters, return to FULL choke, then slowly move to
OFF position.
To Stop Engine
• Run engine for a few minutes before stopping to
help dry off any moisture on the engine.
• To help prevent possible freeze-up of starter,
proceed as follows.
Electric Starter:
• Connect power cord to switch box on engine, then
to 120 volt AC receptacle. With the engine running,
push starter button and spin the starter for several
seconds. The unusual sound made by spinning the
starter will not harm engine or starter. Disconnect
the power cord from receptacle first, and then from
switch box.
Recoil Starter
• With engine running, pull starter rope with a rapid,
continuous full arm stroke three or four times.
Pulling the starter rope will produce a loud clattering
sound, which is not harmful to the engine or starter.
• To stop engine, move throttle control to “stop” or
“off” position.
• Remove ignition key. Do not turn key.
• Disconnect the spark plug wire from the spark plug
to prevent accidental starting while equipment is
unattended.
NOTE: Do not lose ignition key. Keep it in a safe place.
Engine will not start without the ignition key.
• Wipe all snow and moisture from the carburetor
cover in the area of the control levers. Also, move
control levers back and forth several times.
To Engage Augers
• To engage the augers and start throwing snow,
squeeze the auger control grip against the left
handle. Release to stop the augers.
Auger Control Test
IMPORTANT:
operating your snow thrower for the first time and at the
start of each winter season.
Check the adjustment of the auger control as follows:
• When the auger control is released and in the
disengaged “up” position, the cable should have
very little slack. It should NOT be tight.
• In a well-ventilated area, start the snow thrower
engine as instructed earlier in this section under the
heading Starting Engine. Make sure the throttle is
set in the FAST position.
• While standing in the operator’s position (behind
the snow thrower), engage the auger.
• Allow the auger to remain engaged for
approximately ten (10) seconds before releasing
the auger control. Repeat this several times.
• With the engine running in the FAST position and
the auger control lever in the disengaged “up”
position, walk to the front of the machine.
• Confirm that the auger has completely stopped
rotating and shows NO signs of motion.
IMPORTANT:
immediately return to the operator’s position and shut
off the engine. Wait for ALL moving parts to stop before
re-adjusting the auger control.
• To readjust the control cable, loosen the hex jam
nut on the auger control cable “Z” fitting.
• Rotate the coupling end of the cable
counterclockwise to provide more slack.
• Retighten the hex jam nut. See Figure 6.
• Repeat Auger Control Test to verify proper
adjustment has been achieved.
Perform the following test before
If the auger shows ANY signs of rotating,
To Engage Drive
• With the engine running near top speed, move the
shift lever into one of the six FORWARD positions
or two REVERSE positions. Select a speed
8
Auger
Control
Z-End
Jam Nut
Auger
Control Cable
Snow Thrower Model Drift Cutter Kit
All models OEM-390-679
Drift
Cutter
Figure 6
Chute Clean-Out Tool
The chute clean-out tool is conveniently fastened to the
rear of the auger housing with a mounting clip. Should
snow and ice lodge itself in the discharge chute during
operation, proceed as follows to safely clean the chute
and chute opening:
• Release both the Auger Control Lever and the
Traction/Auger Control Lock Lever
• Stop the engine by removing the ignition key.
• Remove the clean-out tool from the clip which
secures it to the rear of the auger housing.
• Use the shovel-shaped end of the clean-out tool to
dislodge and scoop any snow and ice which has
formed in and near the discharge chute.
WARNING: Never use your hands to clean
snow and ice from the discharge chute or
auger housing
• Refasten the clean-out tool to the mounting clip on
the rear of the auger housing, reinsert the ignition
key and start the snow thrower’s engine.
• While standing in the operator’s position (behind
the snow thrower), engage the auger clutch lever
for a few seconds to clear any remaining snow and
ice from the discharge chute.
.
Drift Cutters (If Equipped)
Drift cutters should be used when operating the snow
thrower in heavy drift conditions.
On models so equipped, drift cutters are assembled to
the auger housing inverted. Remove the carriage bolts
by unthreading the hex nuts which secure them, and
reinstall the drift cutters in their proper position before
operating the snow thrower. See Figure 7.
If your unit is not equipped with drift cutters, contact
Customer Support as instructed on page 2 for
information regarding price and availability.
Carriage Screws /
Hex Nuts
Figure 7
Tire Chains (If Equipped)
Tire chains should be used whenever extra traction is
needed. If your unit is not equipped with tire chains,
contact Customer Support as instructed on page 2 for
information regarding price and availability.
Operating Tips
NOTE: Allow the engine to warm up for a few minutes.
The engine will not develop full power until it reaches
operating temperature.
WARNING: The temperature of the muffler
and the surrounding areas may exceed
°
150
F. Avoid these areas.
• For the most efficient snow removal, remove snow
immediately after it falls.
• Discharge the snow downwind whenever possible.
• Slightly overlap each previous path.
• Set the skid shoes 1/4" below the shave plate for
normal usage. The skid shoes may be adjusted
upward (to lower the shave plate) for hard-packed
snow. Adjust downward (to raise the shave plate)
when using on gravel or crushed rock.
• Be certain to follow the precautions found in the To
Stop Engine section to prevent possible freeze-up.
• Clean the snow thrower thoroughly after each use.
9
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