Daewoo DLM3900-150, User Manual

Manufactured under license of 

Daewoo International Corporation

, Korea

www.daewoopowerproducts.com

USER'S MANUAL

DLM

3900-150

EN - GASOLINE LAWN MOWER

CZ - BENZINOVÁ SEKAČKA NA TRÁVU

SK - BENZÍNOVÁ KOSAČKA

HU - BENZINES FŰNYÍRÓ GÉP

NOTE: 

If any grass residue is caught in the discharge chute, clean it using a brush. Do not 

remove grass debris in the mower casing or on the blade by hand or with your feet. Instead use 
suitable tools such as a brush or broom. To ensure that the cut grass can be collected into grass 
bag, the discharge opening and inside the mower casing must be cleared of any blockage.

8. STORING AND MAINTENANCE

NOTE: 

Before performing any maintenance or cleaning work, switch Off the engine and wait 

until the blade has come to a stop.

General cleaning

The lawn mower should be cleaned thoroughly every time after it has been used. Always clean your 
lawnmower immediately after use.Donotallow grass cuttings and other debris to become dryand 
hard onanyof the mower surfaces. Dried grass remnants and dirt may impair the mowing operation. 

Check that the grass chute is free of any residual grass. Remove any such residue. Check the 
underside of the lawn mower and the blade mount for this purpose, tilt the lawn mower onto its left 
side (opposite the oill filler neck)

NOTE: 

Before placing the lawn mower on its side , fully drain the fuel tank using a petrol extrac-

tion pump. Do not tilt the lawn mower by more than 90 degrees.

Maintenance of the spark plug.

As shown in Fig 19

1. Once the engine has cooled , pull off the spark plug with a twist.
2. Remove the spark plug using a spark plug wrench.
3. Clean the spark plugh with a wire brush(not supplied ).
4. Using a feeler gauge set the gapto 0.75mm
5. Install the spark plug carefully byhand, to avoid cross-threading.
6. After the spark plug is seated, tighten withthe spanner to compress the washer.

How to Service the Air Filter

As shown in Fig 20-22

Soiled air filters reduce the engine output by supply too little air to the carburetor. if the air contains 
a lot of dust , the air filter should be checked more frequently .

WARNING: 

Never run the engine without the air filter element installed.

1. Remove the air cleaner outside cover. Be careful to prevent dirt and debris from falling into the air 
cleaner assembly.
2. Separate the air filter from the air filter housing.
3. Inspect the air filter. Clean dirty air filter with warm water and mild soap. Allow air filter todry 
thoroughly before re-installation
4. Install the air filter assembly onto the carburetor and secure with screw.

NOTE:

 Do not use pressurized air or solvents to clean the filter. Pressurized air ca ndamage the 

filter and solvents will dissolve the filter.

Changing the engine oil

Tilt the lawnmower towards the oil filler, have a container ready to catch the oil and remove the 
dipstick once the oil has been emptied, replace the dipstick and wipe clean any spillages. 
Refill with 400ml SAE30 oil or equivalent i. e SAE5W/30, SAE10W/30. When the dipstick is rested on the 
filler pipe (i.e. not turn in pace), the oil level must be between the min and max marks on the dipstick.
See “Checking the engine oil level and filling with engine oil”
Start the engine and allow it to run briefly.
Stop the engine ,wait one minute and check the oil level top up if necessary.

Replacing the blade

For safety reasons you should only ever have your blade sharpened, balanced and mounted by an 
authorised service workshop. For optimum results it is recommended that the blade should be 
inspected once a year.

WARNING: 

Before you remove the grass collection bag, stop the engine and wait until the 

blade stops completely.

WARNING: 

You will need garden gloves (not provided) and a spanner wrench(not provided) to 

remove the blade.

NOTE: 

Don’t invert the mower. Tip it slightly towards the oil filler pipe and reach under the deck.

WARNING: 

Always handle the blade with care, sharp edges could cause injury USE GLOVES. 

Renew your metal blade after 50Hrs mowing or 2yrs whichever is sooner regardless of condition

WARNING: 

If the blade is cracked or damaged replace it with a new one.

WARNING: 

Don’t hold the blade by hand directly.

NOTE: 

Maintain the sharpness of the blade when cutting grass. If the blade has worn excessi-

vely and become pitted and blunt, it should be replaced or sharpened. The sharpness of the blade 
will affect the performance of the lawnmower.

Storing the lawnmower for short periods

The lawnmower can be stored for short periods of time (less than 15 days) without performing any 
storage maintenance.Before placing the lawnmower into storage always carry out the following: 
1. Allow the engine to fully cool.
2. Ensure the grass bagis empty.
3. Clean all debris from under the mower deck.
4. Store the lawnmower on flat and level surface with the mower upright.
5. Store in a safe place which isnot accessible by children or people wh oare not familiar with operation.

Storing the lawnmower for extended periods

If the lawnmower is to be place into storage for more than 15 days, storage maintenance must be 
performed on the lawnmower. If the following steps are not carried out, when you next operate the 
lawnmower it may not start correctly and may need to be serviced.

CAUTION: 

Do not empty the petrol tank in enclosed areas, near fire or when smoking. Petrol 

fumes can cause explosions and fire.

1. Empty the petrol tank with a petrol suction pump if available.
2. Start the engine and let it run until any remaining petrol has been used up.
3. Change the oil at the end of every season. To do so, remove the usedengine oil from a warm 
engine and refill with fresh oil
4. Clean the cooling fins of the cylinder and the housing
5. Be sure to clean the entire machine to protect the paint.
6. Store the machine in a well-ventilated place.

Maintenance Schedule

Performing routine maintenance correctly on your lawnmower will ensure you get years of trouble 
free use.
Please keep this manual safe for future reference.
It is recommended that the following maintenance schedule is adhered to. This will ensure the 
lawn-mower operated correctly and is safe to use.

The Engine oil should be changed after the fist 8 hours.

Transport

Empty the petrol tank.
Always let the engine run until it has used up the remainder of petrol in the tank. 
Empty the engine oil from the warm engine.
Remove the spark plug boot from the spark plug.
Clean the cooling fins of the cylinder and the housing.
Use the original packaging to ship whenever possible.

9. TROUBLESHOOTING

WARNING: 

Before performing any maintenance or cleaning work, switch off the engine and 

wait until the blade has come to a stop.

CAUTION: 

Improper repairs can result in the product functioning unsafely. This endangers 

yourself and your environment.

Faults which cannot be rectified with the aid of following table may be rectified by a specialist 
company only (customer service center).
Please be aware that any improper repairs will also invalidate the warranty and additional costs may 
be incurred.
Use only genuine spare parts. Only these spare parts are designed and suitable for the product. The use 
of other spare parts not only voids the warranty, you can also endanger yourself andyour environment.

3. Pull the engine start/stop lever toward upper handle.
4.Operate the starter as described above.

WARNING: 

Always observe the strictest safety procedures when using the lawnmower. Carefu-

lly read the safety instructions of this manual before using the lawnmower.

WARNING: 

Never open the ejector flap when the grass bag has been detached (to be emptied) 

and the engine is still running. The rotating blade can cause serious injuries!

1. Select your required setting.
2. Start the engine and allow itrun, and set itto required speed.See“to start the engine”.3.Keep a 
firm grip on the upper handle with engine stop/start lever and drive lever (clutch lever) closed and 
walk along with it self-propelling to start mowing.

Working advices

1. Walk, never run with the mower, be very careful when mowing uneven or rou ghground.
2. Mow across slopes, never up and down.
3. Be careful when changing the direction of the mower on a slope.
4. Do not mow excessively steep slopes.
5. The best result will be achieved if the grass is dry. Wet grass will tend to clog the blade and the 
grass collection system.6.Grass grows at different rates at different time of the year. Never use the 
lowest cutti ngheight for the first cut of the season orin drought conditions.
7. Only about one thirds of the grass height should be cut.
8. When mowing with mulching, to ensure that the cut grass can be scattered efficiently, donot cut 
high or wet grass. When you have been cutting for several minutes, please stop the mower, and 
clean the blade and the deck.
9. Do not remove grass debris in the mower casing oron the blade by hand or with your feet. Instead 
use suitable tools such as a brush or broom.

Emptying the grass bag

As soon as grass clippings start to trail the lawn mower, it is time to empty the grass bag.

NOTE: 

Before taking off the grass bag, switch off the engine and wait until the

blade has come to a stop.

1. To take off the grass bag, use one hand to lift up ejector flap and the other to grab onto the carry 
handle. The ejector flap automatically falls down after removing the grass bag and closes off the 
rear chute opening.
2. Empty the grass debris in the grass bag, and refit grass bag.

NOTE: 

do not operate the machine in enclosed or poorly Ventilated areas as the exhaust gas 

contains toxic substance. Keep hands , feet ,hair and clothing away from All the moving parts of the 
machine . the exhaust and other Parts of the machine will become hot during use.
Make sure that the blade is securely fastened before starting the engine.

NOTE: 

to start the engine , make sure that the spark Plug boot is located on the plug and the 

machine is filled with sufficient oil and petrol.

To start the engine

As shown in Fig 14-16

1. When starting a cold engine, press down the Primer fully 3-5 times. (For lawnmower with throttle 
control Need to put the throttle control lever on the START position before starting)

WARNING: 

Too much presses on primer May cause engine flooded when starting a warm 

Engine, the primer does not need to be used. If the Engine stops due to a lack of petrol, refill and 
press Down the primer 3~5 times.

2. Stand behind the mower . Pull the engine Start/ stop lever toward upper handle With one hand 
and place the other hand on the starter handle.
3. Pull the starter handle out approx.. 10-15cm until you feel a resistance and then start the engine 
with a sharp pull.

NOTE: 

If the engine fails to start after three pulls, repeat the process. 

4. Once the engine is running, put the starter rope Into the rope guide as shown in Fig 16 to stop the 
engine as shown in Fig 17 release the engine start/stop lever, it will return to its Initial position, the 
engine will automatically switches off. 

To clean a flooded engine

NOTE: 

if the engine won’t start after you have Operated the starter several times ,the engine 

may be flood with excess fuel . Use following procedure to clear and start aflooded engine.

1.Release the engine start/stop lever to stop engine.
2.Remove the spark plug, dry it, and then reinstall it.

NOTE: 

Install the spark plug carefully by hand, to avoid cross-threading. After the plug is 

seated tighten 1/8 to 1/4 turn with socket spanner of spark plug to compress the washer.

must be filled with the correct grade of oil and petrol before starting the engine.

WARNING:

 Refuel in a well-ventilated area with the engine stopped. Do not smoke orallow 

flame or sparks in the area where the engine is refueled or where petrol is stored. Avoid repeated or 
prolonged contact with skin or inhalation of vapour

1. Clean the area around the petrol filler capbefore removing the cap. Remove the warning tag,check 
the fuel level.
2. Refill the tank if the fuel level is low.
3. Refuel carefully to avoid overfilling or spilling fuel.There should beno fuel in the filler neck.
4. Clean up any overflow or splashes of petrol beforestarting the engine.
5. Tighten the filler cap after filling, finger tight on.

ADJUSTMENT
Setting the cutting height

As shown in Fig 13

CAUTION: 

Adjust the cutting height only when the engine is switch off the spark plug Boothas 

been pulled.

You can adjust the cutting height of the machine according to the following methods, the cutting 
height is 30-65mm.

7. OPERATION

Start and stop the engine

WARNING: 

the blade begins to rotate Assoon as the engine is started.

Checking the engine oil level and filling with engine oil

As shown in Fig 10 -11

CAUTION: 

The following procedures and adjustments must be performed before the engineis 

started. Do not attempt to make any of these adjustments while the engine is running.

CAUTION: 

To prevent engine damage the engine is shipped without oil or petrol. The engine 

must be filled with the correct grade of oil and petrol before starting the engine.

NOTE: 

Running the engine with a low oil level will cause engine damage. It is recommend that 

high detergent, premium quality 4-stroke engine oil used. Using non-detergent oil can shorten the 
engine’s service life and using 2-stroke oil will damage the engine.

CAUTION: 

Always use high quality detergent oil classified SAE30 oil (or equivalent e. g SAE 

10W/30, often termed as 4 Stroke lawn mower oil).Never use additives with recommended oil. To 
prolong the life of your engine it is important that the oilis changed after the first 5 hours of use.

NOTE:

 To Check the engine oil level, stop engine and place the mower on a level surface.

1. Remove the oil filler dipstick and wipe oil from it with a clean cloth.
2. Insert the dipstick into the oil filler neck, but do not turn it in.
3. Then remove the dipstick and check the oil Level . the oil level must be between the Min and Max 
marks on the dipstick. If near the lower level ,fill to upper lever with the recommended oil  ((SAE30 or 
equivalent). Do not overfill. Wipe away any spilt oil.)
4. Align the ribs of the cap with the groove of the filler neck . then rotate 1/4 turn to secure it.
 

Filling with engine fuel

As shown in Fig 12

CAUTION: 

Always use clean, fresh unleaded petrol. Purchase fuel in quantities that can be 

used within 30 days. Never mix oil with petrol.

CAUTION: 

Do not fill into the base of neck to allow for fuel expansion. Do not overfill the fuel tank.

CAUTION WARNING: 

Petrol is highly flammable and extreme precaution must be taken when 

handling or working with it. Keep out of reach of children.

CAUTION: 

To prevent engine damage the engine is shipped without oil or petrol. The engine 

Tidy the connection cord

As show in Fig 5

Fix the connection cord to the handle with the cord clip. (supplied)

Assembling the grass bag

As shown in Fig 6

1. Clip the plastic clips over the metal frame. Make sure that these clips are fully secured to the 
metal frame.

Assembling the grass bag on to the mower

As show in Fig 7

1. Lift the rear discharge cover with one h and and hook in the grass bag .
2. Release the rear discharge cover to secure the grass bag in position

16. Do not start the engine when standing in front of the discharge chute;
17. Do not put hands or feet near or under rotating parts. Keep clear of the dischargeopening at all times;
18. Never pick up or carry a lawnmower while the engine is running;
19. Stop the engine and disconnect the spark plug wire , make sure that all moving parts have come 
to a complete stop and, where a key is fitted remove the key:
-Before clearing blockages or unclogging chute;
-Before checking, cleaning or working on the lawnmower;
-After striking a foreign object. Inspect the lawnmower for damage and make repairs before restar-
ting and operating the lawnmower;
-If lawnmower starts to vibrate abnormally (check immediately);
20. Stop the engine and disconnect the spark plug wire, make sure that all moving parts have come 
to a complete stop and, where a key is fitted remove the key:
-Whenever you leave the lawnmower;
-Before refueling;
21. Reduce the throttle setting during engine shut down and, if the engine is provided with a shut-off 
valve, turn the fuel off at the conclusion of mowing;
22. Go slow when using a trailing seat.

Maintenance and storage

1. Keep all nuts, bolts and screws tight to be sure the equipment is in safe workingcondition;
2. Never store the equipment with petrol in the tank inside a building where fumes can reach an 
open flame or spark;
3. Allow the engine to cool before storing in any enclosure;
4. To reduce the fire hazard, keep the engine, silencer, battery compartment and petrol storage area 
free of grass, leaves, or excessive grease;
5. Check the grass catcher frequently for wear or deterioration;
6. Replace worn or damaged parts for safety;
7. If the fuel tank has to be drained, this should be done outdoors

6. ASSEMBLY

Assembling the handle

As show in Fig 3&4

1. Put the lower push rod into the push rod connection hole on the chassis, and then fix it on the 
chassis with screws.
2. Unfold the upper handle and fix it to lower handle By using the big knobs and the blots on each side.

NOTE: 

I

Make sure the rope guide is on the right handle, when you stand behind the mower.

5. SAFETY INSTRUCTIONS

Training

1. Read the instructions carefully. Be familiar with the controls and the proper use of the equipment;
2. Never allow children or people unfamiliar with these instructions to use thelawnmower. Local 
regulations can restrict the ageof the operator;
3. Never mow while people, especially children, or pets are nearby;
4. Keep in mind that the operator or user is responsible for accidents or hazards occurring to other 
people or their property.

Preparation

1. While mowing, always wear substantial footwear and long trousers. Do not operate the equipment 
when barefoot or wearing open sandals;
2. Thoroughly inspect the area where the equipment is to be used and remove all objects which can 
be thrown by the machine;
3. Warning - petrol is highly flammable.
- Store fuel in containers specifically designed for this purpose;
- Refuel outdoors only and donot smoke while refueling;
- Add fuel before starting the engine. Never remove the cap of the fuel tank or add petrol while the 
engine is running or when the engine is hot;
- If petrol is spilled, do not attempt to start the engine but move the machine away fromthe area of 
spillage and avoid creating any source of ignition until petrol vapours have dissipated;
- Replace all fuel tank and container caps securely;
4. Replace faulty silencers;
5. Before using, always visually inspect to see that the blades, blade bolts and cutter assembly are 
not worn or damaged. Replace worn or damaged blades and bolts in sets to preserve balance;
6. On multi-bladed machines, take care as rotating one blade can cause other blades to rotate.

Operation

1. Do not operate the engine in a confined space where dangerous carbon monoxide fumes can collect;
2. Mow only in daylight or in good artificial light;
3. Avoid operating the equipment in wet grass, where feasible;
4. Always be sure of your footing on slopes;
5. Walk, never run;
6. For wheeled rotary machines, mow across the face of slopes, never upand down;
7. Exercise extreme caution when changing direction on slopes;
8. Do not mow excessively steep slopes;
9. Use extreme caution when reversing or pulling the lawnmower towards you;
10. Stop the blade(s) if the lawnmower has to be tilted for transportation when crossing surfaces 
other than grass, and when transporting the lawnmower to and from the area to be mowed;
11. Never operate the lawnmower with defective guards, or without safety devices, for example 
deflectors and/or grass catchers, in place;
12. Do not change the engine governor settings or over speed the engine;
13. Disengage all blade and drive clutches before starting the engine;
14. Start the engine or switch on the motor carefully according to instructions and withfeet well 
away from the blade(s);
15. Do not tilt the lawnmower when starting the engine or switching on the motor, exceptif the lawn-
mower has to be tilted for starting. In this case, do not tilt it more than absolutely necessary and lift 
only the part which is away from the operator;