Service Engine

Avoid Fumes

c CAUTION: Avoid injury! Engine exhaust fumes contain carbon monoxide and can cause serious illness or death.

Do not run an engine in an enclosed area, such as a garage, even with doors or windows opened.

Move the machine to an outside area before running the engine.

Engine Oil

Use oil viscosity based on the expected air temperature range during the period between oil changes.

The following John Deere oils are preferred:

• TURF-GARD™

• PLUS- 4™

• PLUS-50™ II

Other oils may be used if above John Deere oils are not available, provided they meet the following specification:

• API Service Classification SJ or higher

Checking Engine Oil Level


IMPORTANT: Avoid damage! Failure to check the oil level regularly could lead to serious engine problems if oil level is out of the operating range: • Check oil level before operating. • Check oil level when the engine is cold and not running. • Keep oil level between the dipstick marks. • Shut off engine before adding oil.

NOTE: Check oil twice a day if you run engine over 4 hours in a day.

Make sure engine is cold when checking engine oil level.

1. Park machine safely. (See Parking Safely in the SAFETY section.)


IMPORTANT: Avoid damage! Dirt and contamination can enter engine when checking oil level. Clean area around dipstick before loosening or removing.

2. Clean area around dipstick to prevent debris from falling into crankcase.

MX48863

Picture Note: Single cylinder engine shown.

MX48864

Picture Note: Standard twin cylinder engine shown.

3. Remove dipstick (A). Wipe with clean cloth.

4. Install and tighten dipstick.

5. Remove dipstick.

6. Check oil level on dipstick. Oil must be between ADD and FULL marks.

7. If oil level is low, add oil to bring oil level no higher than FULL mark on dipstick. Do not overfill.

8. Install and tighten dipstick.

Changing Engine Oil and Filter


IMPORTANT: Avoid damage! Operating in extreme conditions may require more frequent service intervals: • Engine components may become dirty or plugged when operating in extreme heat, dust or other severe conditions. • Engine oil can degrade if machine is operated constantly at slow or low engine speeds or for frequent short periods of time.

1. Run engine to warm oil.

2. Park machine safely on level surface. (See Parking Safely in the SAFETY section.)


IMPORTANT: Avoid damage! Dirt and contamination can enter engine when checking oil level. Clean area around dipstick before loosening or removing.

3. Clean area around dipstick to prevent debris from falling into crankcase.

Twin Cylinder (Z225 and Z425):

MX49117, MX49118

1. Install drain hose onto drain valve fitting (A) and position drain pan under free end of hose.

2. Loosen dipstick (B). Open drain valve (C) and allow oil to drain completely.

3. Wipe dirt from around oil filter (D). Place a drain pan under oil filter, and remove filter.

4. Put a light coat of fresh, clean oil on the new filter gasket.

5. Install replacement oil filter by turning oil filter to the right (clockwise) until the rubber gasket contacts filter base. Tighten filter an additional one-half turn.

6. Tighten oil drain valve (C) and remove drain hose.

7. Add oil no higher than FULL mark on dipstick. Begin with approximately 1.6 L (1.75 qt). Do not overfill.

8. Tighten dipstick.

9. Start and run engine at idle to check for leaks. Stop engine. Fix any leaks before operating.

10. Check oil level. Add oil if necessary.

Cyclonic Twin Cylinder (Z645):

MX48926

MX49116

1. Remove end (A) of hose from engine shroud (B) and lower hose. Position drain pan under hose.

2. Loosen dipstick (C). Remove drain cap (D) on hose end and allow oil to drain completely.

3. Wipe dirt from around oil filter (E). Place a drain pan under oil filter, and remove filter.

4. Put a light coat of fresh, clean oil on the new filter gasket.

5. Install replacement oil filter by turning oil filter to the right (clockwise) until the rubber gasket contacts filter base. Tighten filter an additional one-half turn.

6. Install oil drain cap (D) and install hose end (A) onto engine shroud (B).

7. Add oil no higher than FULL mark on dipstick. Begin with 1.6 L (1.75 qt). Do not overfill.

8. Tighten dipstick.

9. Start and run engine at idle to check for leaks. Stop engine. Fix any leaks before operating.

10. Check oil level. Add oil if necessary.

Cleaning Air Intake Screen and Engine Fins

c CAUTION: Avoid injury! Compressed air can cause debris to fly a long distance.

• Clear work area of bystanders.

• Wear eye protection when using compressed air for cleaning purposes.

• Reduce compressed air pressure to 210 kPa (30 psi).


IMPORTANT: Avoid damage! An obstructed air intake screen can cause engine damage due to overheating. Keep air intake screen and other external surfaces of the engine, including cooling fins, clean at all times to allow adequate air intake.

1. Park machine safely. (See Parking Safely in the SAFETY Section.)

2. Clean air intake screen on top of engine and external surfaces with rag, brush, vacuum or compressed air.

Checking and Cleaning Air Cleaner Elements (Twin Cylinder)

1. Park machine safely. (See Parking Safely in the SAFETY section.)

2. Let engine cool.

MX45577

3. Clean dirt and debris from the air cleaner cover (A).

4. Loosen two knobs (B) and remove cover.


IMPORTANT: Avoid damage! To prevent engine damage, do not allow any foreign objects to fall into the carburetor air intake.

NOTE: During filter cartridge removal, any material or foreign object that enters the air intake must be removed before replacement of the cartridge.

MX45578

5. Lift out filter cartridge (D) and inspect it for damage.


IMPORTANT: Avoid damage! Dirt and debris can enter the engine through a damaged filter element: • Do not wash paper element. • Do not attempt to clean paper element by tapping against another object. • Do not use pressurized air to clean element. • Replace element only if it is very dirty, damaged or the seal is cracked.

6. Inspect the foam precleaner (E) without removing it. If the foam precleaner is dirty:

a. Remove it from the filter carefully.

b. Wash precleaner in a solution of warm water and liquid detergent.

c. Rinse precleaner thoroughly. Squeeze out excess water in a dry cloth until precleaner is completely dry.

7. Clean air cleaner housing carefully. Prevent any dirt from falling into carburetor.

8. Install foam precleaner mesh side up.

9. Install cartridge. Make sure cartridge and seal are properly seated and sealing the carburetor air intake area.

10. Install air cleaner cover and tighten knobs. Do not overtighten.

Checking Spark Plug

c CAUTION: Avoid injury! Touching hot surfaces can burn skin. The engine, components, and fluids will be hot if the engine has been running. Allow the engine to cool before servicing or working near the engine and components.

1. Park machine safely (See Parking Safely in the SAFETY section).

MX48871

Picture Note: Single cylinder engine shown.

MX48954

Picture Note: Standard twin cylinder engine shown.

2. Disconnect spark plug wire (A). For the twin cylinder engines, there is a spark plug (B) on each side of engine.

3. Remove each spark plug.

4. Clean spark plug carefully with a wire brush.

5. Inspect spark plug for:

• Cracked porcelain.

• Pitted or damaged electrodes.

• Other wear or damage.

NOTE: In Canada, replace spark plug with resistor plug only.

6. Replace spark plug(s) as necessary.

M85200

7. Check plug gap (C) with a wire feeler gauge. To change gap, move the outer electrode. Gap must be 0.75 mm (0.030 in.).

8. Install spark plugs and tighten to 20 N•m (180 lb-in.).

9. Connect spark plug wire(s).

Adjusting Carburetor

NOTE: Carburetor is calibrated by the engine manufacturer and is not adjustable.

If engine is operated at altitudes above 1006 m (3,300 ft), some carburetors may require a special high altitude main jet. See your authorized dealer.

If engine is hard to start or runs rough, check the TROUBLESHOOTING section of this manual.

Possible engine surging will occur at high throttle with transmission in “N” neutral and mower engagement lever disengaged. This is a normal condition due to the emission control system.

After performing the checks in the troubleshooting section and your engine is still not performing correctly, contact your authorized dealer.

Replacing Fuel Filter

c CAUTION: Avoid injury! Fuel vapors are explosive and flammable:

• Do not smoke while handling fuel.

• Keep fuel away from flames or sparks.

• Shut off engine before servicing.

• Cool engine before servicing.

• Work in a well-ventilated area.

• Clean up spilled fuel immediately.

NOTE: Change filter when fuel is low.

1. Park machine safely. (See Parking Safely in the SAFETY section).

2. Let engine cool.

3. Raise operator’s seat if required.

4. Put a drain pan under fuel filter.

MX49117

Picture Note: Standard twin cylinder engine shown.

5. Slide hose clamps on both sides of fuel filter (A) away from fuel filter ends using pliers.

6. Disconnect hoses from filter.


IMPORTANT: Avoid damage! Incorrect installation of fuel filter may cause engine damage. Install the filter with the arrow pointing in the direction of fuel flow (towards the engine) for proper operation.

7. Connect hoses to new filter making sure the filter arrow is pointing in the direction of the fuel flow.

8. Install clamps and check for leaks.

Cleaning Engine Shroud


IMPORTANT: Avoid damage! An obstructed air intake screen can cause engine damage due to overheating. Keep air intake screen and other external surfaces of the engine, including cooling fins, clean at all times to allow adequate air intake.

Standard Twin Cylinder (Z225 and Z425)

1. Park machine safely. (See Parking Safely in the SAFETY Section.)

2. Clean air intake screen and external engine surfaces (see Cleaning Air Intake Screen and Engine Fins in ENGINE Section).

MX45576

Picture Note: Twin cylinder shown.

3. Locate rotating screen guard (A) at top of engine, and the two retaining tabs (B), embossed with a finger symbol.

4. Push in on the two retaining tabs and lift off guard (A).

5. Clean guard and flywheel cover of debris.


IMPORTANT: Avoid damage! Be careful to maintain position of fuel pump assembly (D), clips (E) for fuel line, and any other attached components when removing parts from side of engine.

6. Remove bolts and engine shroud (C).

7. Remove four bolts and rotating screen (F).

MX38389

8. Clean debris from:

• Fan areas (G)

• Cylinder head cooling fins (H)

• Engine cooling fins

• Area between engine and frame

9. Install rotating screen with four bolts.


IMPORTANT: Avoid damage! Engine shroud must be assembled so that the slots in the shroud align with the ridge in the air intake and mating surfaces along sides of engine. Failure to assemble correctly will prevent the air filter from sealing and may cause engine damage.

10. Install shroud with hardware.

Cyclonic Twin Cylinder (Z645)

1. Park machine safely. (See Parking Safely in the SAFETY Section.)

2. Clean air intake screen and external engine surfaces (see Cleaning Air Intake Screen and Engine Fins in ENGINE Section).

MX47213

3. Loosen two knobs (A) and remove cover (B).

4. Remove four screws (C) and rotating screen guard (D).

MX47418

5. Remove two screws holding fuel pump (E) to side of engine.

6. Remove four hex head screws (F) and washers holding screen (G) to engine. Remove screen and plate under screen.

7. Remove two bolts (H) on top of engine shroud (I).


IMPORTANT: Avoid damage! Be careful to maintain position of fuel pump assembly (E), clips for fuel line, and any other attached components when removing parts from side of engine.

8. Loosen remaining bolts and remove engine shroud (I).

MX47419

9. Clean debris from:

• Fan areas (G)

• Cylinder head cooling fins (H)

• Engine cooling fins

• Area between engine and frame


IMPORTANT: Avoid damage! Engine shroud must be assembled so that the slots in the shroud align with the ridge in the air intake and mating surfaces along sides of engine. Failure to assemble correctly will prevent the air filter from sealing and may cause engine damage.

10. Install shroud, engine screen, fuel pump, and remaining components, reverse of removal.

Cleaning Engine Screen Guard

Z225, Z425

The Briggs and Stratton twin cylinder engines incorporate a removable guard over the rotating flywheel cover at the top of the engine. The guard should be removed to check for and remove any debris daily in conjunction with checking engine oil level.

MX48869

1. Remove screw (A) securing rotating screen guard (B) at top of engine.

MX48870

2. Push in on the two retaining tabs (C) (embossed with a finger symbol) and lift off screen guard (B).

3. Clean guard and flywheel cover of debris.

4. Install guard after cleaning, making sure retaining tabs (C) are fully installed into retaining tab slots (D). Secure with screw (A).