MTD 8Q78HU Owner’s Manual
Safe Operation Practices • Set-Up • Operation • Maintenance • Troubleshooting • Warranty
OperatOr’s Manual
679 cc OHV Vertical Shaft Engine
WARNING
READ AND FOLLOW ALL SAFETY RULES AND INSTRUCTIONS IN THIS MANUAL
BEFORE ATTEMPTING TO OPERATE THIS ENGINE.
FAILURE TO COMPLY WITH THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.
MTD LLC, P.O. BOX 361131 CLEVELAND, OHIO 44136-0019
Form No. 769-12954
(January 4, 2018)
To The Owner
1
Thank You
This Operator’s Manual is an important part of your new engine. It will help you prepare and maintain the engine for the best performance. Please read
and understand the contents before operating the engine.
Table of Contents
Important Safe Operation Practices ....................................... 3
Safety Labels .............................................................................4
Set-Up .........................................................................................5
Controls & Features ..................................................................6
Operation ..................................................................................7
Engine Maintenance ................................................................8
Troubleshooting......................................................................12
Replacement Parts ..................................................................13
Spanish ....................................................................................17
Record Product Information
Before operating your new engine, please locate the model plate on the engine (shaded area in Figure below) and record the information in the
provided area below. This information will be necessary, should you seek technical support via our web site or with your local dealer.
Model Number
Serial Number
Customer Support
Please do NOT return the machine to the retailer or dealer without first contacting the Customer Support Department.
If you have difficulty assembling this product, have questions regarding the controls, operation, or maintenance of this machine, want to order
replacement parts/attachments/accessories, or want to view an online How-To video; you can seek help from the experts. Have your full model number
and serial number ready. Choose from the options below:
• Web: www.mtdproducts.com/equipment/mtdproducts
• Phone: (800) 800-7310
• Mail: MTD LLC • P.O. Box 361131 • Cleveland, OH • 44136-0019
2
Important Safe Operation Practices
2
WARNING!
This symbol points out important safety
instructions which, if not followed, could endanger
the personal safety and/or propert y of yourself
and others. Read and follow all inst ructions
in this manual before attempting to operate
the equipment. Failure to comply with these
instructions may result in personal injury. When
you see this symbol. HEED ITS WARNING!
WARNING!
CALIFORNIA PROPOSITION 65
Engine Exhaust, some of its cons tituents, and
certain vehicle components contain or emit
chemicals known to State of California to cause
cancer and birth de fects or other reproduc tive
harm.
DANGER!
This engine was built to be operated according to
the safe operation practices in this manual. As with
any type of power equipment, carelessness or error
on the part of the operator can result in serious
injury. Failure to obser ve the following safety
instructions could result in serious injury or death.
Training
1. Read, understand and follow all
instructions on the engine 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
engine and disengage them quickly.
3. Never allow children under 14 years of
age to operate the engine. Children 14
and over should read and understand the
instructions and safe operation practices
in this manual and be trained and
supervised by an adult.
4. Never allow adults to operate the machine
without proper instruction.
5. Keep the area of operation clear of all
persons, particularly small children and
pets. Stop machine if anyone enters the
area.
Preparation
1. Wear sturdy, rough-soled work shoes and
close fitting slacks and shirts. Loose fitting
clothes or jewelry can be caught in the
moving parts. Never operate the machine
in bare feet or sandals.
2. Disengage clutch levers and shift (if
equipped) into neutral (“N”) before
starting the engine.
3. Never leave the engine running while
unattended.
4. Never attempt to make any adjustments
while the engine is running, except
where specifically recommended in the
operator’s manual.
Safe Handling of Gasoline:
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 and/or your
clothes which can ignite. Wash your skin and
change clothes immediately.
1. When adding fuel, turn engine OFF and
let engine cool at least 2 minutes before
removing the gas cap.
2. Fill fuel tank outdoors or in well ventilated
area.
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 not use
a nozzle lock-open device.
7. Do not overfill fuel tank. Fill tank to full
as indicated by the fuel level indicator
installed inside of the fuel tank or marked
on the tank. Do not over-fill to allow space
for fuel expansion. On some models, a fuel
level indicator may NOT be present, in this
instance, fill the tank no more than 1/2
inch below the bottom of the filler neck to
allow space for fuel expansion.
8. Replace fuel cap and tighten until the cap
ratchets.
9. If gasoline is spilled, wipe it off the engine
and the equipment. Move the machine
to another area. Wait five minutes before
starting the engine.
10. To reduce fire hazards, keep the machine
free of grass , leaves or other debris
build up. Clean up oil or fuel spillage and
remove any fuel-soaked debris.
11. Keep gasoline away from sparks, open
flames, pilot lights, heat, and other
ignition sources.
12. Never fuel equipment indoors because
flammable vapors will accumulate in the
area.
13. Extinguish all cigarettes, cigars, pipes, and
other sources of ignition.
14. Check fuel line, tank, cap, and fittings
frequently for cracks or leaks. Replace if
necessary.
Operation
1. When starting the engine, make sure spark
plug, muffler, and fuel cap are in place.
2. Do not crank engine with spark plug
removed.
3. If fuel spills, wait until it evaporates before
starting engine.
4. Allow muffler, engine cylinder, and fins to
cool before touching.
5. Keep children away from hot or running
engines. They can suffer burns from a hot
muffler.
6. Remove accumulated combustibles from
muffler and cylinder area.
7. Operate equipment with all guards in
place.
8. Keep hands and feet away from rotating
parts.
9. Tie up long hair and remove jewelry.
10. Do not wear loose-fitting clothing,
dangling drawstrings or items that could
become caught.
11. When starting the engine, pull cord slowly
until resistance is felt, then pull rapidly (if
not electric start).
12. Remove all external equipment/engine
loads before starting engine.
13. Direct coupled equipment components
such as, but not limited to blades,
impellers, pulleys, sprockets, etc., must be
securely attached.
3
Maintenance & Storage
1. Keep the engine in safe working order
2. Allow the engine to cool at least five
minutes before storing. Never tamper
with safety devices. Check their proper
operation regularly.
3. Check bolts and screws for proper
tightness at frequent intervals to keep the
engine in safe working condition. Visually
inspect the engine for any damage.
4. Before cleaning, repairing or inspecting;
stop the engine and make certain all
moving parts have stopped. Disconnect
the spark plug wire and ground it against
the engine to prevent unintended
starting.
5. Do not change the engine governor
settings or over-speed the engine. The
governor controls the maximum safe
operating speed of the engine.
6. Maintain and replace safety and
instruction labels as necessary.
7. Always refer to the operator’s manual for
important details if the machine is to be
stored for an extended period of time.
8. If the fuel tank has to be drained, do this
outdoors.
9. Observe proper disposal laws and
regulations for gas, oil, etc. to protect the
environment.
Do not modify engine
To avoid serious injury or death, do not modify
engine in any way. Tampering with the governor
setting can lead to a runaway engine and cause
it to operate at unsafe speeds. Never tamper
with factory setting of engine governor.
Notice Regarding Emissions
Engines which are certified to comply with
California and federal EPA emission regulations
for SORE (Small Off Road Equipment) are
certified to operate on regular unleaded
gasoline, and may include the following
emission control systems: Engine Modification
(EM), Oxidizing Catalyst (OC), Secondary Air
Injection (SAI) and Three Way Catalyst (TWC) if
so equipped.
Spark Arrestor
WARNING!
This machine is equipped with an internal
combustion engine and should not be used on
or near any unimproved for est-covered, brush
covered or grass-covered land unless the engine’s
exhaust s ystem is equipped with a spark ar restor
meeting applicable local or s tate laws (if any).
If a spark arrestor 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 arrestor 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.
Safety Symbols
This page depicts and describes safety symbols that may appear on this product. Read, understand, and follow all instructions on the machine before
attempting to assemble and operate.
Symbol Description
READ THE OPERATOR’S MANUAL(S)
Read, understand, and follow all instructions in the manual(s) before attempting to assemble and
operate.
WARNING—GASOLINE IS FLAMMABLE
Allow the engine to cool at least two minutes before refueling.
WARNING— CARBON MONOXIDE
Never run an engine indoors or in a poorly ventilated area. Engine exhaust contains carbon monoxide, an
odorless and deadly gas.
WARNING— ELECTRICAL SHOCK
Do not use the engine’s electric starter in the rain.
WARNING— HOT SURFACE
Engine parts, especially the muffler, become extremely hot during operation. Allow engine and muffler
to cool before touching.
WARNING! - SAVE THESE INSTRUCTIONS!
Your Responsibility — Restrict the use of this power machine to persons who read, understand and follow the warnings and instruc tions in this manual and on the
machine.
4 Section 2 — important Safe operation practiceS
Set- Up
3
Gas & Oil
NOTE: The engine is shipped without gasoline
and with motor oil in the engine. However, you
MUST check the oil level before operating. Be
careful not to overfill. Running the engine with
insufficient oil can cause serious engine damage
and void the engine warranty.
WARNING!
Always keep hands and feet c lear of equipment
moving par ts. Do not use a pressurized starting
fluid. Vapors are flammable.
Oil Recommendations
Before starting engine, check oil level, capacity
is 1900 ml/64.25 fl. oz. Refer to viscosity chart
in Figure 3-1 for oil recommendations. Do
not over-fill. Use a 4-stroke, or an equivalent
high detergent, premium quality motor oil
certified to meet or exceed U.S. automobile
manufacturer’s requirements for service
classification of a minimum level SJ (higher
letter ratings are acceptable such as SL and SM
grades). Motor oil will display this designation
on the container.
SAE 10W-30 is recommended for general, all
temperature use. If single viscosity oil is used,
select the appropriate viscosity for the average
temperature in your area from the chart below.
30
Synthetic 5W-30
10W-30
5W-30
(ºC)
-30º -20º -10º 0º
(ºF)
0º 15º 30º 50º 70º 85º 105º
-20º
Figure 3-1
CAUTION: Do not use non-detergent oil or
2-stroke engine oil. It could shorten the engine’s
service life.
NOTE: A 5w30 synthetic oil may be used
to improve start ability for cold weather
(temperatures below 40 F).
Checking Oil Level
NOTE: Be sure to check the oil while on a level
surface with the engine stopped.
1. Remove the oil filler cap/dipstick and
wipe the dipstick clean.
2. Insert the dipstick into the oil filler neck.
Turn the dipstick a 1/4 turn into the
locked position to fully seat. See Figure
3-2.
10º 20º 30º 40º
Upper
Level
Figure 3-2
3. Remove dipstick to check the oil level.
4. If the level is low, slowly add oil to the
upper limit on the dipstick. See Figure
3-2 inset.
5. Reinsert the dipstick and turn to the
locked position before starting the
engine.
NOTE: Do not overfill. Overfilling with
oil may cause smoking, hard starting,
spark plug fouling, hydraulic lock, or oil
saturation of air cleaner.
Fuel Requirements
CAUTION
Operating the engine with E15 or E85 fuel, an oil/
gasoline mixture, dirty gasoline, or gasoline
over 30 days old without fuel stabilizing
additive may result in damage to your engine’s
carburetor. Subsequent damage would not be
covered under the manufacturer’s warranty.
Use automotive gasoline (unleaded or low
leaded to minimize combustion chamber
deposits) with a minimum of 87 octane.
Gasoline with up to 10% ethanol (E10) or 15%
MTBE (Methyl Tertiary Butyl Ether) can be used.
Never use an oil/gasoline mixture or dirty
gasoline. Avoid getting dirt, dust, or water in the
fuel tank. DO NOT use E15 or E85 gasoline.
WARNING!
WARNING! Gasoline is ex tremely flammable and is
explosive under certain conditions.
• Refuel in a well-ventilated area with the
engine stopped. Do not smoke or allow
flames or sparks in the area where the
engine is refueled or where gasoline is
stored.
• Do not overfill the fuel tank. After
refueling, make sure the tank cap is
closed properly and securely.
• Be careful not to spill fuel when refueling.
Spilled fuel or fuel vapor may ignite. If
any fuel is spilled, make sure the area is
dry before starting the engine.
• Avoid repeated or prolonged contact
with skin or breathing of vapor.
Adding Fuel
WARNING!
WARNING! An adult should fuel this engine. NEVER
allow child ren to refuel the engine. Gasoline (fuel)
vapors are highly flammable and can explode.
Fuel vapors can spread and be igni ted by a spark
or flame many feet away fr om engine. To prevent
injury or death from fuel fires, follow these
instructions:
• DO NOT use leaded fuel.
• Fuel must be f resh and clean. NEVER use
fuel lef t over from last season or stored for
long periods.
• NEVER mix oil w ith fuel in this engine.
• DO NOT use fuel containing Methanol
(Wood Alcohol).
NOTE: Before refueling, allow engine to cool
two minutes.
1. Clean around fuel fill before removing
cap to fuel.
2. Fill tank until fuel reaches ⁄ inch below
the bottom of the filler neck to allow
space for fuel expansion. Be careful not
to overfill.
3. Replace the fuel cap and tighten securely.
Wipe up spilled fuel before starting
engine. If fuel is spilled DO NOT start
engine. Move machine away from area
of spillage. Avoid creating any source of
ignition until fuel vapors are gone.
NOTE: For more information regarding fuel,
refer to Operator’s Manual shipped with
machine.
5
Controls and Features
Finger Guard
Electric
Starter
Spark Plug
4
Air Cleaner
Throttle
Control
Oil Drain
Throttle/Choke Control
The throttle/choke control is located on the
mower and is used to aid in starting/stopping
the engine and adjusting engine speeds. Refer
to the Controls and Features section of the
mower manual for more information regarding
this control.
Spark Plug
Oil Fill Cap
Oil Filter
Figure 4-1
Oil Drain
Opening the oil drain valve will drain the oil
from the engine. The engine is equipped with a
side drain.
Oil Fill Cap
Remove the oil fill cap to check the oil level and
add oil.
Fuel Cap
Remove the fuel cap to add fuel. Refer to the
Operator’s Manual shipped with machine for
the location of the fuel cap.
6
Operation
5
Pre-Operation Check
The engine is shipped without gasoline and
with oil in the engine. See the Set-Up Section of
this manual for instructions on adding gasoline
and checking oil.
Starting Engine
Turn-Key Ignition
1. Insert the tractor key into the ignition
module.
2. Place the PTO/Blade Engage lever to
OFF position.
3. Engage the tractor’s parking brake
.
4. Push the choke control (if equipped)
upward into the choke on
position.
Note: If the engine is warmed up, it
may not be necessary to place the
choke control in the choke position.
5. Move the throttle control lever to
midway between the FAST
SLOW positions.
Note: When operating the tractor
be certain that the throttle lever
is always in the FAST
position. Operating with the throttle
at less than full throttle may lead to
shortened battery life.
and
(rabbit)
6. Turn the ignition key clockwise to the
START
starts, release the key. It will return to
the NORMAL MOWING
Do NOT hold the key in the START
longer than ten seconds at a time. Doing so may
cause damage to your engine’s electric starter.
6. After the engine starts, deactivate
the choke control (if equipped).
Note: Do NOT leave the choke
control (if equipped) on while
operating the tractor. Doing so will
result in a “rich” fuel mixture and
cause the engine to run poorly.
Stop
Position
position. After the engine
position.
CAUTION
position for
Run
Position
Start
Position
Stopping Engine
WARNING!
If you strike a foreign object, stop the engine and
disconnect the spark plug wire(s). Thoroughly
inspec t the machine for any damage. Repair the
damage before restarting and operating.
1. If the blades are ENGAGED (ON), place the
PTO in the DISENGAGED (OFF) position.
2. Place the throttle near the SLOW
position.
3. Engage the parking brake.
• Turn Key Start: Turn the ignition
key counterclockwise to the STOP
position.
• Push Button Start: Press or
remove the ignition key.
Figure 5-1
7
Engine Maintenance
6
WARNING: Shut off the engine
before performing any
maintenance. To prevent
accidental start-up, disconnect
the spark plug boot.
Periodic inspection and adjustment of the
engine is essential if high level performance is
to be maintained. Regular maintenance will also
ensure a long service life. The required service
intervals and the kind of maintenance to be
performed are described in the table below.
Follow the hourly or calendar intervals,
whichever occur first. More frequent service is
required when operating in adverse conditions.
Maintenance Schedule
After First
5 Hours
Check Engine Oil Level
Change Engine Oil ††
Change Engine Oil FIlter ††
Check Air Cleaner
Service Air Cleaner †
Check Spark Plug
Replace Spark Plug
Clean Cooling Fins
Replace Fuel Filter
Clean Finger Guard and around Muffler
† Service more frequently when used in dusty areas.
†† Every season or 25 hours if operating under heavy load or high ambient temperature.
P P
Each use
or Every
5-10 Hrs.
P
P
P
Every
Season or
25 Hours
P
P
Every
season or
100 Hours
P
P
P
P
WARNING: If the engine has
been running, the muffler will be
very hot. Be careful not to touch
the muffler.
Service Dates
Oil Service
• Check oil level regularly.
• Be sure correct oil level is maintained.
Check every five to ten hours before
starting engine. See oil checking
procedure in the Set-Up section.
Oil Drain
IMPORTANT: Be sure to check engine on a level
surface with the engine stopped. Drain the oil
while the engine is still warm to assure rapid
and complete draining.
1. Locate the oil drain valve (a) and place a
suitable container below the plug.
2. Remove the drain cap (b).
NOTE: If necessary, push the oil drain hose (if
provided) onto the oil drain valve. Route the
opposite end of the hose into an appropriate
oil collection container with at least a 2.5 quart
capacity, to collect the used oil.
8
3. Turn the drain plug valve 1/4 turn
counterclockwise while gently pulling
the valve away from the engine to open
the oil drain valve.
4. Allow oil to drain into a suitable
container.
5. Reverse STEPS 4-3 to close the oil drain
valve and reinstall the drain cap.
IMPORTANT: Used motor oil may cause skin
cancer if repeatedly left in contact with the skin
for prolonged periods. Although this is unlikely
unless you handle used oil on a daily basis, it is
still advisable to thoroughly wash your hands
with soap and water as soon as possible after
handling used oil.
NOTE: Please dispose of used motor oil
in a manner that is compatible with the
environment. Check with your local municipality
for proper disposal procedure. Do not throw it
in the trash or pour it on the ground.
1
2
(a)
(b)
Figure 6-1
(a)
3
(a)
Replace Oil Filter
This engine is equipped with a spin-on oil filter
that should be replaced each time an oil change
is performed, every season or 50 hours. Refer to
Figure 6-5.
2. Remove dipstick and wipe clean with a
cloth.
3. Pour oil into the dipstick tube. Do not
over fill. With an oil filter change the high
level amount of oil for this engine is 1900
ml (64.25 fl. oz.).
4. Install dipstick and turn to locked
position before starting engine.
5. Start engine. Allow to run for a few
seconds and then shut down the engine.
6. Check the oil level. See Checking Oil Level
section.
1
2
Oil Filter
Figure 6-2
1. Drain oil. See oil drain section.
2. Remove oil filter. Dispose of old oil filter
properly.
3. Lube gasket of new oil filter with clean oil.
4. Install and turn oil filter by hand until the
gasket comes in contact with the sealing
surface of the crankcase cover, then
tighten the oil filter, 10-12 Nm (88.5-106.2
in-lb), 1/2-3/4 turn.
5. Add oil. See add oil section.
6. Make sure dipstick is installed.
7. Start and run engine. Check for leaks.
8. Stop engine. Wait a few minutes and
check the oil level. See checking oil level
section.
9. Install and tighten dipstick.
Add Oil
IMPORTANT: Be sure to check engine on a level
surface with the engine stopped.
1. Wipe around dipstick cap and tube with
a clean cloth to remove any debris. See
Figure 6-3.
Air Filter Service
Paper filters cannot be cleaned and should be
replaced every 100 operating hours; more often
if used in extremely dusty conditions.
WARNING: Never use gasoline or
low flash point solvents for
cleaning the air filter element. A
fire or explosion could result.
IMPORTANT: Never run the engine without the
air filter. Rapid engine wear will result.
1. Unscrew a 1/4 turn and remove the
thumb screws.
2. Remove the air filter cover. See Figure
6-4.
1
2
Air Filter Cover
Thumb Screw
Figure 6-4
3. Remove thumb screw.
4. Pull up and remove air filter and base
seal. See Figure 6-5.
Figure 6-5
5. Remove the foam pre-filter from around
the paper air filter. See Figure 6-6.
Replace paper element when dirty or
damaged. Clean foam element or replace
when damaged.
NOTE: The foam element cannot be
purchased separately. Air filter is only
sold as an assembly.
Air Filter
Pre-Filter
Figure 6-6
6. To clean foam element, wash in a mild
liquid detergent and water. Squeeze
or press the foam element to rinse out
dirt and water. Do not twist; this could
damage or tear the foam element. Allow
to dry thoroughly before using. DO NOT
oil the foam element.
7. Attach the new air filter with foam
element, aligning the hole in the air filter
with the intake manifold. See Figure 6-6.
Figure 6-3
9Section 6 — Maintenance
Spark Plug Service
WARNING: DO NOT check for
spark with spark plug removed.
DO NOT crank engine with spark
plug removed.
Electrode
Intake
Manifold
Figure 6-7
8. Attach the air filter cover. See Figure 6-8.
Turn thumb screws clockwise a 1/4 turn
until snug. Check for any misalignment.
2
Air Filter
Cover
1
Figure 6-8
WARNING: If the engine has
been running, the muffler will be
very hot. Be careful not to touch
the muffler.
To ensure proper engine operation, the spark
plug must be properly gapped and free of
deposits.
1. Remove the spark plug boot and use a
spark plug wrench to remove the plug.
See Figure 6-9.
Spark Plug
Boot
Figure 6-9
2. Visually inspect the spark plug. Discard
the spark plug if there is apparent wear,
or if the insulator is cracked or chipped.
Clean the spark plug with a wire brush if
it is to be reused.
3. Measure the plug gap with a feeler
gauge. Correct as necessary by bending
electrode. See Figure 6-10. The gap
should be set to 0.024-0.031 in.
0.024-0.031 in.
Figure 6-10
4. Check that the spark plug washer is in
good condition and thread the spark plug
in by hand to prevent cross-threading.
5. After the spark plug is seated, tighten
with a spark plug wrench to compress the
washer.
NOTE: When installing a new spark plug,
tighten 1/2 turn after the spark plug
seats to compress the washer. When
reinstalling a used spark plug, tighten
1/8-1/4 turn after the spark plug seats to
compress the washer.
IMPORTANT: The spark plug must be
securely tightened. An improperly
tightened spark plug can become very
hot and may damage the engine.
6. Repeat STEPS 1-5 to service the
remaining spark plug.
10 Section 6 — Maintenance
Loading...