Operator’s Manual
21” Rear & Side Discharge
Mulching Lawn Mower
Model 437
IMPORTANT: Read safety rules and instructions carefully before operating equipment.
Warning:
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 t he State of California t he 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.
This unit is equipped with an internal combustion engine and should not be used on or near any unimproved forest-covered, brush-
MTD LLC, P.O. BOX 361131 CLEVELAND, OHIO 44136-0019
PRINTED IN U.S.A.
FORM NO.
769-00668.fm
(1/2003)
TABLE OF CONTENTS
Content Page
Important Safe Operation Practices ...................................................................... 3
Slope Gauge ......................................................................................................... 6
Assembling Your Lawn Mower .............................................................................. 7
Know Your Lawn Mower........................................................................................ 9
Operating Your Lawn Mower............................................................................... 10
Maintaining Your Lawn Mower............................................................................ 12
Service................................................................................................................ 13
Making Adjustments............................................................................................ 14
Off- Season Storage............................................................................................ 15
Troubleshooting .................................................................................................. 15
Parts List ............................................................................................................. 16
FINDING MODEL NUMBER
This Operator’s Manual is an important part of your new Lawn Mower. 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 equipme nt, 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 our Customer Support Department or an
authorized dealer.
• You can locate the model number by standing behind the unit in the operating position and looking down at
the rear of the deck. 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.
(Model Number)
www.yardman.com
(Serial Number)
MTD LLC
P. O. BOX
CLEVELAND,OH
330-220-4683
800-800-7310
361131
44136
Copy the model number here:
Copy the serial number here:
ENGINE INFORMATION
The engine manufacturer is responsible for all engine-related issues with regards to performance, power-rating,
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 CUSTOME R SUPPORT
If 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.yar dman.com
2
SECTION 1: IMPORTANT SAFE OPERATION PRACTICES
WARNING:
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:
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.
WARNING:
This symbol points out important safety instructions which, if not followed, could endanger
This machine was built to be operated according to the rules for safe operation in this
Engine exhaust, some of its constituents, and cer tain vehicle components contain or
emit chemicals known to Stat e of Califor nia to cause ca ncer and birth defects or other
reproductive harm.
General Operation
1. Read this operator’s manual carefully in its entirety
before attempting to assemble this machine. Read,
understand, and follow all instructions on the
machine and in the manual(s) before operation. Be
completely familiar with the controls and the proper
use of this machine before operating it. Keep this
manual in a safe place for future and regular
reference and for ordering replacement parts.
2. This machine is a precision piece of power
equipment, not a plaything. Therefore, exercise
extreme caution at all times. Your unit has been
designed to perform one job: to mow grass. Do not
use it for any other purpose.
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. Only
responsible individuals who are familiar with these
safe operation rules should use this machine.
4. Thoroughly inspect the area where the equipment
is to be used. Remove all stones, sticks, wire,
bones, toys and other foreign objects which could
be tripped over or picked up and thrown by the
blade. Thrown obje cts can cause se rious person al
injury. Plan your mowing pattern to avoid discharge
of material toward roads, sidewalks, bystanders
and the like. Also, avoid discharging material
against a wall or obstruction which may cause
discharged material to ricochet toward operator.
5. To help avoid blade contact or a thrown object
injury, stay in the operator zone behind the handles
and keep bystanders, helpers, children and pets at
least 75 feet from the machine while it is in
operation. Stop machine if anyone enters the area.
6. Always wear safety glasses or safety goggles
during operation and while performing an
adjustment or repair to protect your eyes. Thrown
objects which rico chet can cause se rious injury to
the eyes.
7. Wear sturdy, rough-soled work shoes and closefitting slacks and shirts. Shirts and pants that cover
the arms and legs and steel-toed shoes are
recommended. Never operate this machine in bare
feet, sandals, slippery or light weight (e.g. canvas)
shoes.
8. Do not put hands or feet near rotating parts or
under the cutting deck. Contact with the blade can
amputate hands and feet.
9. A missing or damaged discharge cover can cause
blade contact or thrown object injuries.
10. Many injuries occur as a result of the mower being
pulled over the foot during a fall caused by slipping
or tripping. Do not hold on to the mower if you are
falling; release the handle immediately.
11. Never pull the mower back toward you while you
are walking. If you must back the mower away from
a wall or obstruction first look down and behind to
avoid tripping and then follow these steps:
a. Step back from the mower to fully extend
your arms.
b. Be sure you are well balanced with sure
footing.
c. Pull the mower back slowly, no more than
half way toward you.
d. Repeat these steps as needed.
5. Do not operate the mower while under the influence
of alcohol or drugs.
6. Do not engage the self-propelled mechanism on
units so equipped while starting engine.
7. The blade control handle is a safety device. Never
attempt to bypass its operation. Doing so makes
the safety device inoperative and may result in
personal injury through contact with the rotating
blade. The blade control handle must operate
easily in both directions and automatically return to
the disengaged position when released.
3
8. Never operate the mower in wet grass. Always be
sure of your footing. A slip and fall can cause
serious personal injury. If you feel you are losing
your footing, release the blade control handle
immediately and the blade will stop rotating within
three seconds.
9. Mow in daylight or good artificial light. Walk, never
run. Stop the blade when crossing gravel drives,
walkways or roads.
10. If the equipment should start to vibrate abnormally,
stop the engine and check immediately for the
cause. Vibration is generally a warning of trouble.
11. Shut the engine off and wait until the blade comes
to a complete stop before removing the grass
catcher or unclogging the chute. The cutting blade
continues to rotate for a few seconds after the
engine is shut off. Never place any part of the body
in the blade area until you are sure the blade has
stopped rotating.
12. Never operate mower without proper trail shield,
discharge cover, grass catcher, blade control
handle or other safety protective devices in place
and working. Never operate mower with damaged
safety de vices. Failur e t o do s o, can resu lt in
personal injury.
13. Muffler and engine become hot and can cause a
burn. Do not touch.
14. Only use parts and accessories made for this
machine by the original equipment manufacturer
(O.E.M). Failure to do so can cause personal injury.
15. If situations occur which are not covered in this
manual, use care and good judgment. Contact your
dealer for assistance. Telephone 1-800-800-7310
for the name of your nearest dealer.
Do Not:
1. Do not mow near drop-offs, ditches or
embankments, you could lose your footing or
balance.
2. Do not mow slopes greater than 15 degrees as
shown on the slope gauge.
3. Do not mow on wet grass. Unstable footing could
cause slipping.
Children
Tragic acci dents can oc cur if the op erator is not aler t to
the presen ce of ch ildren. Childr en are o ften at tracte d to
the mower and the mowing activity. They do not
understand the dangers. Never assume that children
will remain where you last saw them.
1. Keep children out of the mowing area and under
the watchful care of a responsible adult other than
the operator.
2. Be alert and turn mower off if a child enters the
area.
3. Before and while moving backwards, look behind
and down for small children.
4. Use extreme care when approaching blind corners,
doorways, shrubs, trees, or other objects that may
obscure your vision of a child who may run into the
mower.
5. Keep children away from hot or running engines.
They can suffer burns from a hot muffler.
6. Never allow children under 14 years old to operate
a power mower. 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.
Slope Operation
Slopes are a major factor related to slip and fall
accidents which can result in severe injury. Operation
on slopes requires extra caution. If you feel uneasy on a
slope, do not mow it. Before operating this unit on a
slope or hilly area, use the slope gauge on page 6 to
measure slopes. If the slope is greater than 15 degrees,
do not mow it.
Do:
1. Mow across the face of slopes; never up and down.
Exercise extreme caution when changing direction
on slopes.
2. Watch for holes, ruts, rocks, hidden objects, or
bumps which can cause you to slip or trip. Tall
grass can hide obst acles.
3. Always be sure of your footing. A slip and fall can
cause serious personal injury. If you feel you are
losing your balance, release the blade control
handle immediately, and the blade will stop rotating
within 3 second s.
Service
Safe Handling of Gasoline
1. 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.
2. Wash your skin and change clothes immediately.
3. Use only an approved gasoline container.
4. Never fill containers inside a vehicle or on a truck or
trailer bed with a plastic liner. Always place
containers on the ground away from your vehicle
before filling.
5. If possible, remove gas-powered equipment from
the truck or trailer and refuel it on the ground. If this
is not possible, then refuel such equipment on a
trailer with a portable container, rather than from a
gasoline dispenser nozzle.
6. Keep the nozzle in contact with the rim of the fuel
tank or container opening at all times until fueling is
complete. Do no t use a nozzle lock-ope n device.
4
7. Extinguish all cigarettes, cigars, pipes and other
sources of ignition.
8. Never fuel machine indoors because flammable
vapors will accumul ate in the area.
9. Never remove gas cap or add fuel while the engine
is hot or running. Allow engine to cool at least two
minutes before refueling.
10. Never over fill fuel tank. Fill tank to no more than ½
inch below bottom of filler neck to provide space for
fuel expansion.
11. Replace gasoline cap and tighten securely.
12. If gasoline is spilled, wipe it off the engine and
equipment. Move unit to another area. Wait 5
minutes before starting the engine.
13. Never store the machine or fuel container inside
where there is an open flame, spark or pilot light as
on a water heater, space heater, furnace, clothes
dryer or other gas appliances.
14. To reduce fire hazard, keep mower free of grass,
leaves, or other debris build-up. Clean up oil or fuel
spillage and remove any fuel soaked debris.
15. Allow a mower to cool at least 5 minutes before
storing.
General Service
1. Never run an engine indoors or in a poorly
ventilated area. Engine exhaust contains carbon
monoxide, an odorless and deadly gas.
2. Before cleaning, repairing, or inspecting, make
certain the blade and all moving parts have
stopped. Disconnect the spark plug wire and
ground against the engine to prevent unintended
starting.
3. Check the blade and engine mounting bolts at
frequent intervals for proper tightness. Also,
visually inspect blade for damage (e.g., bent,
cracked, worn) Replace blade with the original
equipment manufacture’s (O.E.M.) blade only,
listed in this manual. “Use of parts which do not
meet the original equipment specifications may
lead to improper performance and compromise
safety!”
4. Mower blades are sharp and can cut. Wrap the
blade or wear gloves, and use extra caution when
servicing them.
5. Keep all nuts, bolts, and screws tight to be sure the
equipment is in safe working condition.
6. Never tamper with safety devi ces. Check their
proper operation regularly.
7. After striking a foreign object, stop the engine,
disconnect the spark plug wire and ground against
the engine. Thoroughly inspect the mower for any
damage. Repair the damage before starting and
operating the mower.
8. Never attempt to make a wheel or cutting height
adjustment while the engine is running.
9. Grass catcher components, discharge cover, and
trail shield are subject to wear and damage which
could expose moving parts or allow objects to be
thrown. For safety protection, frequently check
components and replace immediately with original
equipment manufacturer’s (O.E.M.) parts only,
listed in this manual. “Use of parts which do not
meet the original equipment specifications may
lead to improper performance and compromise
safety!”
10. Do not change the engine governor setting or
overspeed the engine. The governor controls the
maximum safe operating speed of the engine.
11. Maintain or replace safety and instruction labels, as
necessary.
12. Observe proper disposal laws and regulations.
Improper disposal of fluids and materials can harm
the environm ent.
Y our Responsibility
• 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.
1299 AC
5
SECTION 2: SLOPE GAUGE
Operate RIDING mowers up and down slopes, never across the face of slopes.
Operate WALK-BEHIND mowers across the face of slopes, never up and down slopes.
Do not mow on inclines with a slope in exces s of 15 degrees (a rise of appr oximately 2-1/2 feet ever y 10 feet). A riding mower cou ld overturn
and cause serious i njury. If op erating a wa lk-behind mower on such a s lope, it is extremely difficult t o maintai n your footi ng and you could s lip,
resulting in serious injury.
F
O
L
D
O
USE THIS PAGE AS A GUIDE TO DETERMINE SLOPES WHERE YOU MAY NOT OPERATE SAFELY.
N
D
O
T
T
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S
E
R
P
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R
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D
L
I
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,
A CORNER OF A BUILDING
SIGHT AND HOLD THIS L EVEL WITH A VERTICAL TREE
A POWER POLE
WARNING
15°
N
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P
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1
5
°
S
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OR A FENCE POST
6
SECTION 3: ASSEMBLING YOUR LAWN MOWER
Removing Unit From Carton
• Remove staples, break glue on top flaps or cut tape
at carton end and peel top flap to open carton.
• Remove loose parts if included with unit.
• Cut corners and lay carton down flat. Remove
packing material.
• Roll or sl ide uni t out of c arton . Chec k car ton
thoroughly for loose parts.
NOTE: M ake sure not to c rimp cables while rem oving
the loose parts or the entire unit from the carton.
Hardware Pack
Please identify each piece
of the hardw are pac k as
shown here.
Wing
Nut
1/4-20 (2)
Carriage
Bolt
1/4-20 (2)
Tools Required
• Pair of Pliers
• Funnel
NOTE: Reference to right or left hand side of the mower
is observed from the operating position.
Disconnecting Spar k Plug
• Before setting up your lawn mower, disconnect the
spark plug wire from the spark plug, and ground it to
retaining post on the engine. See Figure 1.
Figure 1
Assembling Handle
• For shipping purposes, the grass bag was placed
on top of the unit. Remove it from the unit and set it
out of the way. See Figure 2 .
Figure 2
• Raise the lower handle, as shown in Figure 2 , until
it snaps into place.
• Raise the upper handle as shown in Figure 2 .
• Tighten the two wing nuts which are already on the
handle. See Figure 3 .
Tighten these
wing nuts
Lower
Upper
Handle
Figure 3
NOTE: Make sure to route the cables outside the lower
handle. Also do not crimp the cables while lifting the
handle up.
• Remove the hairpin clips from the outer hole in the
weld pins on the handle bracket assemblies. Using
a pair of pliers, squeeze one leg of the lower handle
against the handle bracket assemblies. Insert the
hairpin clip into the inner hole on the weld pin.
Repeat on other side. See Figure 4.
• After you have moved the hairpin clip, install the
carriage bolt, (carriage bolt must go to the inside of
handle) included in the hardware pack, in the upper
hole on the handle mounting bracket. Secure with
one plastic wing nut, also included in the hardware
pack. See Figure 4.Repeat process on other side.
Handle
7
Assembling Grass Catcher
Carriage Bolt
Upper
Hole
Wing Nut
Move Hairpin Clip
Handle
Mounting
Brkt.
Figure 4
• Fasten the cable to the lower handle with the two
cable ties found on the lower handle. Pull the cable
ties tight and trim off the excess. See Figure 5 .
Cable Tie
Post on
Cable Tie
NOTE: If your mower’s grass catcher has been already
assembled before shipping, proceed to the next
section. If it is unassembled, follow the steps below.
• Insert frame into grass bag with the black plastic
side on the bottom of bag. See Figure 7.
Insert frame
into bag
Grass Catcher
Frame
Grass
Bag
Figure 7
• Slip the side openings of the plastic channel on the
bag over the hooks on the grass catcher frame.
Secure bag to the frame by working the six plastic
channels on bag over frame.
• All the pl astic chann els atta ch fr om th e outs ide of
bag. See Figure 8 .
Plastic
Channel
Grass Catcher
Figure 5
Attaching Starter Rope
• The rope guide is attached to the right side of upper
handle. Loosen the wing nut which secures the rope
guide. See Figure 6.
• With the spark plug wire disconnected and
grounded, hold the blade control handle against the
upper handle, and pull the starter rope out of the
engine. Release the blade control handle. Slip the
starter rope into the rope guide. Tighten wing nut.
Slip rope into
rope guide
Wing Nut
Rope
Guide
Figure 8
Attaching Grass Catcher
• Lift the rear discharge door and place the grass
catcher on the pivot rod. Let go of discharge door so
that it rests on the grass catcher. See Figure 9.
Figure 6
Figure 9
8
Removing Grass Catcher
• Lift the rear discharge door on the mower, and lift
the grass cat cher up.
• Release the rear discharge door.
Converting to Side-Dischar ge
• Your mower has been shipped as a mulcher. To
convert it to a side-discharge mower, lift the
mulching plug. Slide the two hooks on the sidedischarge deflector under the hinge pin on the
mulching plug assembly. Lower the mulching plug.
See Figure 10 .
Mulching
Plug
Hinge
Pin
Side
Chute
Deflector
Figure 10
• Do not remove the side mulching plug at any time,
even when you are not mulching.
WARNING:
Never operate the mower
without the mulching cover, the grass catcher
bag, or the discharge chute properly installed.
SECTION 4: KNOW YOUR LAWN MOWER
Read thi s owne r’s manual and safety rules before operating your lawn mower. Compare the illustrations in Figure
11 with your lawn mower to familiarize yourself with the location of various controls and adjustments.
Blade Control
Handle
Recoil Starter
Grass Catcher
Spark Plug
Mulch Plug
Side-Discharge
Chute
Figure 11
Blade Control Handle
The blade control handle is located on the upper handle
of the mower. The blade control handle must be
depressed in order to operate the unit. Release the
blade control handle to stop the engine and the blade.
Height Adjustment
Lever
WARNING:
The blade control handle is a
safety device. Never attempt to bypass its
operations. The blade will be rotating whenever
the engine is running.
9
Cutting Height Adjustment Lever
This lever, located at each wheel, lets you adjust cutting
height of the grass. Remember to put all four levers at
the same height to avoid uneven cut.
Throttle Control
The engine is equipped with a constant speed throttle
for maximum engine and cutting performance.
Recoil Starter
The recoil starter is attached to the handle. Stand
behind the unit and pull the recoil starter to start engine.
Primer
The primer is used to pump gas into the carburetor. Use
it to assist in starting a cold engine, but do not use it
when restarting a warm engine after a short shutdown.
Mulching Plug
The mulching plug is used only for mulching purposes.
Instead of collecting the grass clippings in a grass
catcher, some mower models have the option of
recirculating the clippings back to the lawn. This is
called mulching.
SECTION 5: OPERATING YOUR LAWN MOWER
Gas and Oil Fill-Up
WARNING:
when engine is running or hot. Do not smoke
when filling up the fuel tank.
• Service the engine with gasoline and oil as
instructed in the separate engine manual packed
with your mower. Read instructions carefully.
Never fill fuel tank indoors, or
Before Starting Mower
• Attach spark plug wire to spark plug. Make certain
the metal cap on the end of the spark plug wire is
fastened securely over the metal tip on the spark
plug.
Starting Engine
• Push the primer three times. Wait two seconds
between each push. In temperatures below 55° F,
prime five times. Do not prime to restart a warm
engine after a short shutdown.
• Standing behind the mower, depress the blade
control handle and hold it against the upper handle.
WARNING:
operator is standing near the lawn mower while
starting engine or operating mower.
WARNING:
enclosed, poorly ventilated areas. Engine
exhaust contains carbon monoxide, an
odorless and deadly gas.
WARNING:
loose clothing away from any moving parts on
engine and lawn mower.
• Grasp starter handle and pull rope out slowly until
engine reache s start of comp ression cycl e (rope
will pull slightly harder at this point). Let the rope
rewind slowly. Pull rope with a rapid, continuous,
full arm stroke. Keeping a firm grip on the starter
handle, let the rope rewind slowly.
Be sure no one other than the
Never run engine indoors or in
Keep hands, feet, hair and
Stopping Engine
• Release blade control handle to stop the engine
and the blade.
• Disconnect spark plug wire and move away from
spark plug to prevent accidental starting.
10
Operating Y ou r Lawn Mower
• Once the engine has started, squeeze the blade
control handle against the upper handle to run the
lawn mower.
• Do not operate the mower without the mulching
cover, the grass catcher bag, or the discharge
chute properly installed.
• Be sure that the l awn is clear of sto nes, sticks, wir e,
or other objects which could damage lawn mower
or engine. Such objects could be accidently thrown
by the mower in any direction and cause serious
personal injury to the operator and others.
• For best results, do not cut wet grass because it
tends to stick to the underside of the mower,
preventing proper discharge of grass clippings,
poor mulching conditions, and could cause you to
slip and fall. New grass, thick grass, or wet grass
may require a narrower cut.
• For a healthy lawn, always cut off one-third or less
of the total length of the grass. Lawn should be
trimmed in fall as long as there is growth.
WARNING:
stop the engine. Remove spark plug wire from
spark plug, thoroughly inspect the mower for
any damage. Repair the damage before
restarting and operating the mower. Extensive
vibration of the mower during operation is an
indication of damage.
If you strike a foreign object,
Bagging Grass Clippings
You can use the grass catcher bag to collect clippings
while you are operating the mower.
• Attach the grass c atche r foll owing instruct ions on
page 8 of this manual. Grass clippings will
automatically collect in the bag as you run mower.
• Operate mower till the grass bag is full.
• Stop the engine completely by releasing the control
handle. Make sure that the unit has come to a
complete stop.
• Lift discharge door and pull grass bag up and away
from the mower to dispose of the grass clippings.
Using the Mulcher
• For effective mulching, do not cut wet grass
because it tends to stick to the underside of the
deck, preventing proper mulching of grass
clippings. New or thick grass may require a
narrower cut. The ground speed should be
adjusted to the condition of the lawn. If mowing has
been delayed and the grass has been allowed to
grow in excess of 4", mulching is not
recommended. Mow using the grass bag (if so
equipped) to reduce the grass height to 3-1/4"
maximum before mulching.
Adjusting Cutting Height
Refer to height adjustments section of this manual on
page 14 for instruction on how to adjust the cutting
height and the handle height.
• For best results in mowing, keep the cutting height
position high until you have determined which
cutting height is preferred.
11
SECTION 6: MAINTAINING YOUR LAWN MOWER
WARNING:
disconnect spark plug wire befor e pe rfo rm ing
any maintenance or adjust ments on the mower.
Always stop engine and
IMPORT ANT :
surrounding areas while the mower engine is hot
because temperature of these areas of the engine may
exceed 150
Make sure to av oid muff ler and
o
F.
WARNING:
degrees in any direction and do not leave it
tipped for long. Oil can drain into the upper part
of the engine causing a starting problem.
Never tip mower more than 90
Cleaning the Lawn Mower
• Clean underside of the mower deck after each use
to prevent any build-up of grass. If this debris
accumulates, it will cause rust and corrosion.
NOTE: We do not recommend the use of pressure
washers or garden ho se to clean your unit . T h ese m ay
cause damage to electric components, spindles,
pulleys, bearings or the engine. The use of water wi ll
result in shortened life and reduced serviceability.
• Disconnect spark plug wire. Drain gasoline from the
mower, or place a piece of plastic under gas cap.
• Tilt the mower so that the side with the air cleaner is
facing up. Hold the mower firmly.
• Scrape and clean the underside of the deck with a
suitable tool. Do not spray with water.
• Put mower back on its wheels and remove plastic.
Engine Maintenance
A list of key maintenance jobs required for good
performance by the mower is given below. Follow the
engine manual for detailed list and instructions.
• Change engine oil as specified in the engine
manual. Check oil level before starting engine
every time.
• Service foam filter in the air cleaner as specified in
the engine manual. Service air filter more frequently
in extremely dusty conditions.
• Clean engine periodically. Remove dirt and debris
with a cloth or brush.
• Clean spark plug and reset the gap to.030” at least
once a season or every 50 hours of operation.
• Inspect muffler periodically, and replace if
necessary. Damaged mufflers or spark arresters
can create a fire hazard.
Lubrication
(See Figure 12 )
Wheels
• Lubricate the wheels and bearings, if so equipped,
at least once a season with light oil or engine oil.
Also, if the wheels are removed for any reason,
lubricate the surface of the axle bolt and the inner
surface of the wheel with light oil.
Chute Deflector & Rear Discharge Door
• Lubricate the torsion spring and the pivot point on
each end of the rear discharge door using a light oil.
This will prevent rusting.
Engine
• Follow the engine manual instructions and
recommended schedule for lubricating engine.
Pivot Points
• Lubricate the pivot points on the discharge chute
door, blade control handle and the cutting height
adjustment lever at least once a season with light
oil. The blade control handle must operate freely in
both directions. The cutting height adjustment
levers should be able to move easily.
Lubricate
Lubricate
Follow engine manual
for lubricati on
12
Lubricate
Figure 12
SECTION 7: SERVICING YOUR MOWER
Blade Care
Periodically inspect the blade adapter and pulley for
cracks, especially if you strike a foreign object. Replace
when necessary.
WARNING:
blade for sharpening or replacement, protect
hands by using heavy gloves or a thick rag to
grasp the cutting blade.
• Disconnect spark plug wire from spark plug.
• Turn mower on its side making sure that the air filter
and the carburetor are up.
• Remove the bolt and blade support or bell washer
which hold the blade and adapter to the engine
crankshaft. See Figure 13. Remove the blade and
adapter from the crankshaft.
Blade Adapter
Blade
To Sharpen Blad e:
• The blade can be sharpened with a file or on a
grinding wheel. Do not attempt to sharpen the
blade while it is still on the mower.
• Follow the original angle of grind as a guide. Make
sure that each cutting edge receives an equal
amount of grinding to prevent an unbalanced blade.
When removing the cutting
Blade
Bell
Support
Hex Bolt
Figure 13
NOTE: An unbalanced blade will cause excessive
vibration when rotating at high speeds, may cause
damage to the mower and could break causing
personal injury.
• The blade can be tested by balancing it on a round
shaft screwdriver. See Figure 14. Remove metal
from the heavy side until it balances evenly. It is
recommended that the blade always be removed
from the adapter for the best test of balance.
1. Insert screw driver through hole
2. Blade should be parallel to ground
Screw
Driver
Figure 14
• Before reassembling the blade and the blade
adapter to the unit, lubricate the engine crankshaft
and the inner surface of the blade adapter with light
oil (or engine oil). Also lubricate the bolt holes, bolts
and inner surface of the nuts.
• Install the blade adapter on the crankshaft with the
“star” away from the engine. Refer to Figure 13.
Place the blade with the side marked bottom (or
with part number) facing away from the adapter.
• Align the blade bell support over the blade with the
tabs in the holes of the blade and insert the hex
bolt. Tighten the center bolt to 450 in. lbs. min., 600
in. lbs. max.
IMPORT ANT :
bolts must be checked periodically for correct tightness.
To ensure safe operation, all nuts and
Blade
Ground
13
Replacing Rear Flap
• To remove rear flap, cut off the flat end of the wire
rod which secures it to the deck. See Figure 15 .
SECTION 8: MAKING ADJUSTMENTS
• Attach the new flap and new rod to deck, bending
the ends of the new rod over to secure to deck.
Rear Discharge
Handle
Bracket
Door
o
R
e
r
i
W
Figure 15
d
Rear Flap
Handle
Bracket
Adjusting Handle Height
Your mower is shipped with the handle in the higher
height position. To lower height, proceed as follows.
• Remove the start er ro pe fr om th e rope guid e.
• Remove the upper handle by removing the hand
knobs and carriage bolts. Lay upper handle out of
the way, being careful not to bend or kink cables.
• Remove the hairpi n clip s from the w eld pi ns on t he
handle brackets. Refer to Figure 4 .
• Remove the carriage bolts and wing nuts from the
handle brackets. Press out on the legs of the lower
handle. Remove lower handle from the mower.
• Turn the lower handle
around so the notch on
the bottom of the lower
handle is facing forward
as shown in the box
here. Reassemble,
placing the bottom
holes in the handle over
the weld pins in the
handle mounting
bracket.
• Reassemble the upper
handle to the lower handle.
• Insert hairpin clips in the inner holes of the weld
pins and replace the carriage bolts and wing nuts
on the handle brackets. Attach the starter rope as
instructed in the “Assembling Your Lawn Mower”
section.
Lower
Handle
Notch
Adjusting Cutting Height
IMPORT ANT :
relative position. For rough or uneven lawns, move the
height adjustment lever to a higher position. This will
help stop scalping of the grass.
An adjusting plate and
thumb lever at each wheel
position pr ovides cutting
height adjustment. Each
adjusting plate has nine
height positions. Height of
cut will change when you
move the thumb lever
from one position to
another.
• Simply depress the
lever towards the
wheel and move the lever assembly to desired
position. See the illustration in the box above.
All wheels must be placed in the same
Adjustment
Lever
Adjusting Carburetor
NOTE: A dirty a ir cleaner may cause an engi ne to run
rough too. Make sure that the air cl eaner is clean and
attached to the carburetor before deciding to adjust the
carburetor.
WARNING:
the engine (e.g. carburetor) while the engine is
running, keep clear of all moving parts. Be
careful of heated surfaces like the muffler.
If any adjustments are made to
To adjust carburetor, please follow the engine manual.
14
SECTION 9: OFF-SEASON STORAGE
Prepare your lawn mower for storage at the end of the
season or if the unit will not be used for 30 days or
more. Store the mower in a clean, dry area.
Gasoline
• Do not store gasoline from one season to another.
Gasoline, stored more than one month, may affect
engine performance.
• Replace your gasoline can if it starts to rust. Rust
and/or dirt in the gasoline will cause problems.
Engine
• Follow recommendations in the accompanying
engine manual for off-season storage of the
engine.
Mower
NOTE: If storing the mower in an unven til ate d or me tal
storage shed, make sure to rustproof the equipment
with a light oil or silicone.
• Store unit in a clean, dry area. Do not store next to
• Clean underside of the mower according to
NOTE: The use of a pressure washer or garden hose to
clean your mower is NOT recommended. Water may
cause damage to electric components, spindles,
pulleys, bearings or the engine. The use of water wi ll
result in shortened life and reduce serviceability.
• Lubricate the mower as instructed on page 12.
• You can fold your mower’s handle for convenience
• Inspect and replace/sharpen blade, if required.
SECTION 10: TROUBLE-SHOOTING GUIDE
corrosive ma terial s, such a s fert ilizer or rock salt.
instructions on page 12.
of storage.
Refer to page 13.
Problem Possible Cause Corrective Action
Engine fails to start 1. Blade control handle dise ngaged
2. Spark plug wire di sconnected
3. Fuel ta nk empty, o r stale fuel
4. Blocked fu el li ne
5. Faulty sp ark plug
6. Engine f looded
Engine runs erratic 1. Spark plug wire loose
2. Blocked fuel line or stale fu el
3. Vent in gas cap plugged
4. Water or dirt in fuel system
5. Dirty air cleaner
Engine overheats 1. Engine oil level low
2. Air flow restricted
Occasional skip at high
speed
Idles poorly 1. Spark plug fouled, faulty, or gap too wide
Excessive vibration 1. Cutting blade loose or unba lance d
Fails to mulch grass 1. Wet grass
Uneven cut 1. Wheels not in same height position
1. Spark plug gap too close 1. Adjust gap to.030 inches.
2. Dirty air cleaner
2. Bent cutting blade
3. Bent engine crankshaft
2. Excessively high grass
3. Dull blade
2. Dull blad e
1. Engage blade control handle
2. Connect wire to spark plug
3. Fill up tank with fresh gaso line
4. Clean fuel line
5. Clean, adjust gap, or repla ce
6. Wait a few minutes and start again.
1. Connect and tighten spark p lug wire.
2. Clean fuel line, fill tank with clean, fresh
gasoline.
3. Clear vent.
4. Drain fuel tank. Refill with fres h fuel.
5. Clean air cleaner. Refer to engine manual.
1. Fill crankcase with proper oil.
2. Clean lawn mower engine.
1. Reset gap or replace spark plug.
2. Clean air cleaner.
1. Tighten blade and adapter, balance blade.
2. Replace blade.
3. Contact your nearest service cen ter
1. Wait until grass is dry to cu t.
2. Mow once at a high cutting height, t hen
mow again at de sired hei ght.
3. Sharpen or replace blade.
1. Reposition all wheels at same height.
2. Sharpen or replace blade.
NOTE: For repairs beyond the minor adjustments listed above, contact your nearest authorized service dealer.
15
SECTION 11: PARTS LIST FOR MODEL 437
1
11
51
50
6
3
2
4
9
53
12
18
19
32
35
33
29
17
44
52
30
40
5
41
16
7
56
57
10
23
15
49
13
4
8
54
44
42
12
38
25
31
44
25
48
30
28
29
14
34
45
27
26
25
55
37
20
43
39
36
24
47
46
16
31
44
22
21
Model 437
Ref.
No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
Part No. Description
747-1161A Control Handle
710-1205 Rope Guide
720-0279 Handle Knob 1/4-20 Th d.
710-1174 Curved Hd. Bolt 5/16-18 x 2"
720-0284 Hand Knob
749-1092A Upper Handle
749-0928A Lower Handle
726-0240 Cable Tie
747-04080 Grass Catcher Frame
746-1137 Control Cable
664-04012 Grass Bag (soft top w/l ogo)
714-0104 Int. Cotter Pin 5/16" Dia .
732-04072 Door Spring - R.H.
732-04071 Door Spring - L.H.
731-04134 Rear Discharge Door
732-1014 Torsion Spring
747-0710 Hinge Pin
732-0700 Wire Rod
731-1236 Rear Flap
748-0376C Blade Ad apter w/ Star
710-1044 Hex Bolt 3/8-24 x 1.5 " Lg.
736-0524A Blade Bell Support
17032A Deflector Chute Adap ter
742-0741 21" Mulching Blade w /Star
712-0431 Flange Nut 3/8-16 Thd.
15261A Height Adj. Plate
15262B Pivot Bar
732-0404 Front Spring Lever
738-0507B Shld. Bolt.5" Dia. x.3 57"
736-0105 Bell Washer.38" I.D. x .88" O.D.
Ref.
No.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
Part No. Description
738-0102 Front Axle Bolt
720-0426 Spring Lever Knob
732-0417A Rear Spring Lever
14578 Height Adj. Assy. Com p. - RH
14579 Height Adj. Assy. Com p. - LH
14765 Pivot Bar R.H.
14766 Pivot Bar L.H.
782-5002A Front Baffle
710-0654A Hex L-Wash.Scr. 3/8-16 x 1"
782-5003 Rear Baffle - LH
710-1017 Torx Mach AB-Tap Scr. 1/4 x .62"
710-0896 HexIndWash. Scr. 1/4-1 4:.625
787-01016 Handle Brkt. Ass’y.—RH
787-01015 Handle Brkt. Ass’y.—LH
787-01104 Deck 21”
734-2005A Wheel Complete
736-0270 Bell Washer 1/4" I.D.
731-04161 Hinged Mulching Plug
731-04177 Chute Deflector: Sid e Dischar ge
710-0599 Hex Hd Self-Tp Scr. 1/4-2 0 x.5"
782-5004A Rear Baffle - RH
731-1426 Hub-Cap- Rad. Spoke- Y ellow
738-0213 Rear Axle Bolt
750-0535 Spacer
710-0703 Hex Carriage Screw 1/ 4-20
712-0397 Wing Nut
750-04162 Spacer,.375OD x.50ID
747-04035 Rear Door Pivot Rod
736-0451 Shoulder Washer
17
MANUFACTURER’S LIMIT ED WARRANTY FOR:
The limited warranty s et forth below i s given by MTD L LC with
respect to new me rchand ise purchas ed and u sed in th e
United States, its possess ions an d territorie s.
MTD LLC warrants this produ ct against defe cts for a period of
two (2) years comm encing on the da te of or iginal p urchase
and will, at it s option, repair or re place, fr ee of cha rge, an y
part found to be d efective in materi als or work manship. T his
limited warranty s hall onl y apply if this p roduct has bee n
operated and mainta ined in a ccordanc e with the Operator’s
Manual furnished w ith the product, a nd has n ot been s ubject
to misuse, abuse, commerc ial use , neglect , accide nt,
improper maintenanc e, alterat ion, vand alism, theft, fire,
water, or damage be cause of other peri l or natura l disas ter.
Damage resulti ng from th e instal lation or use of an y
accessory or attachment not approved by MTD LLC for use
with the product(s) covered by this manual will vo id your
warranty as to any resultin g damage .
Normal wear parts or compone nts thereo f are sub ject to
separate terms as f ollows: All normal wear parts or
component failur es will be co vered on the p roduct for a period
of 90 days regardles s of ca use. After 9 0 days, bu t within the
two year period, no rmal wear p art fai lures will be cove red
ONLY IF caused by d efects i n materials or workman ship of
OTHER component parts . Normal wea r parts an d
components inclu de, but are not lim ited to: b atteries, belt s,
blades, blade a dapters, gr ass bags, r ider de ck wheels , seats ,
snow thrower skid sho es, shave plates, a uger spiral ru bber,
and tires.
HOW TO OBTAIN SERVICE: Warranty serv ice is ava ilable,
WITH PROOF OF PURCHASE, through your local authorized
service dealer. To locate th e dealer i n your are a, check your
Yellow Pages, or co ntact MTD LLC at P .O. Box 3 61131,
Cleveland, Ohio 44136-001 9, or call 1 -800-80 0-7310 or l og
on to our Web site at www.mtdproducts.com.
This limited warra nty does not prov ide cove rage in th e
following cases:
a. The engine or compon ent par ts thereof. These it ems
carry a separate manufacturer’s warranty. R efer to
applicable manu facturer’s warranty for te rms and
conditions.
b. Lo g splitte r pumps, valves , and cy linders h ave a
separate one year warra nty.
c. Routine mainten ance ite ms such a s lubr icants, f ilters,
blade sharpening, tune-ups, brake adjustments, cl utch
adjustments, de ck adjus tments, and normal
deterioration of th e exterio r finish d ue to use or
exposure.
d. MTD LLC does not exte nd any warra nty for pr oducts
sold or exported outside o f the Unite d States, its
possessions and territories , except those sold through
MTD LLC’s authorized channels o f expo rt distribu tion.
e. Part s that are not ge nuine MT D parts are not cove red
by this warranty.
f. Service completed by someone other than an
authorized servi ce deale r is not cov ered by this
warranty.
g. Tra nsportatio n charges and se rvice ca lls are n ot
covered.
No implied warranty, including any implied war ranty of
merchantability of fitness fo r a particular p urpose,
applies after the applic able period of express w ritten
warranty above as to the parts as identified. No other
express warranty, wh ether written or oral, ex cept as
mentioned above, given by any person or entity,
including a dealer or re tailer, with respe ct to any product,
shall bind MTD LLC. During the period of the warranty ,
the exclusive remedy is repair or r eplacement o f the
product as set forth above.
The provisions as se t forth in this warranty provide the
sole and exclusive remedy arisi ng from the sale. MTD
LLC shall not be liable for incidental or consequ ential
loss or damage includ ing, without limitation, e xpenses
incurred for substitute or replaceme nt lawn care services
or for rental expense s to temporaril y replac e a warrante d
product.
Some states do not allow the exclusion or limitation of
incidental or co nsequent ial da mages, o r limitat ions o n how
long an implied warranty l asts, so the abov e exclu sions or
limitations may not app ly to you.
In no event shall re covery of any k ind be gre ater than t he
amount of the purcha se price of the pro duct sold. Alteration
of safety features of the product shall void this warranty.
You assume the risk and lia bility fo r loss, dam age, or in jury to
you and your property and/or to others a nd their p roperty
arising out of the misus e or inabi lity t o use the product.
This limited warranty shal l not extend to anyone othe r than the
original purchaser or to the pers on for whom it was purchased
as a gift.
HOW STATE LAW RELATES TO THIS WARRANTY: This
limited warranty g ives yo u specif ic legal rights, a nd you m ay
also have other rights w hich va ry from s tate to sta te.
MTD LLC, P.O. BOX 361131 CLEVELAND, OHIO 441 36-0019; Phone: 1-8 00-800-7310
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