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Kohler M18 / M20 Engine

The Kohler M18 / M20 is a 42.18 L 2-cylinder engine rated at 3600 rpm, producing up to 18 kW. It powers generator sets from Kohler, including the 4 and 5 kW, 4CFKM, 4CKM and 5CKM. It holds 1.6 L (0.4 gal) of oil.

Also known as: Kohler M18 / M20

Part of the Kohler M18 engine family — 2 variants share parts & fitment.

42.18 L

Displacement

Cylinders

3600 rpm

Rated speed

18 kW

Gross power

On this pageSpecs Generator sets Maintenance FAQ Service intervals Torque & specs Fluids Procedures Wiring

Engine specifications

Oil capacity	1.6 L
Displacement	42.18 L
Cylinders	2
Rated speed	3600 rpm
Gross power	18 kW

Generator sets powered by this engine

Kohler 4 and 5 kW Kohler 4CFKM Kohler 4CKM Kohler 5CKMKohler TP-5393

How to read your Kohler engine serial & model number →

Common problems

Will not start
Cause: Out of fuel, Clogged fuel filter, Air cleaner clogged, Faulty spark plug, Shorted or open ignition coil, Faulty ground, Loose spark plug wire connection, Weak or dead battery, Choke adjustment wrong
Fix: Replenish, Replace, Clean or replace, Replace or regap spark plugs, Replace, Clean and retighten, Reconnect and/or tighten, Recharge or replace, Adjust
Will not crank TP-5393
Cause: Weak or dead battery, 15-amp controller fuse blown, Defective start switch, Remote start cable disconnected, Defective starter solenoid, Battery connections made in reverse
Fix: Recharge or replace, Replace fuse, Replace, Reconnect, Replace, Correct
The generator set has automatically stopped.
Cause: Low oil pressure, 3 1/2 psi –1 1/2 psi (24.1 kPa) or less.
Fix: Eliminate the cause before restarting.
Stops suddenly
Cause: Out of fuel, Air cleaner clogged, Faulty spark plug, Low oil pressure
Fix: Replenish, Clean or replace element, Replace or regap spark plugs, Check oil level
Low oil pressure (LOP) shutdown
Cause: Correct cause of shutdown
Hard starting
Cause: Stale or bad fuel, Air cleaner clogged, Carburetor adjustment wrong, Faulty spark plug, Weak ignition coil
Fix: Replace, Clean or replace element, Adjust, Replace or regap spark plugs, Replace
Will not carry load or runs rough
Cause: Fuel line restriction; Vent in fuel tank cap obstructed (gasoline fuel); Dirty fuel filter (gasoline fuel only); Improper type of fuel; Defective fuel pump; Governor not properly adjusted or defective; Carburetor not adjusted or defective; Defective ignition module; Defective/misadjusted spark plug; Carburetor choke; Fuel leak; Valves not sealing; improper valve clearance; Excessive carbon buildup; Fuel vapor lock {hot engine only}
Fix: Inspect fuel lines and tank.; Clean cap in solvent, blow dry; Replace fuel filter; Use specified type of fuel; Check fuel pump pressure is 2-3.5 psi (14-24 kPa); Check speed using tachometer or frequency meter.; NOTE: Hz x 120/ No. of rotor poles=rpm; (Example: 60 x 120/4=1800); Check and/or adjust; Test and/or replace; Regap or replace; Test and/or replace; Tighten fittings; Compression test; Adjust proper valve clearance; Clean cylinder head; Reroute fuel lines away from heat.
While the unit is cranking, is 12 vde present across P1-5(+) to P1-12(-)?
Cause: No
Fix: Replace control board
Unit is noisy
Cause: Exhaust system leak; Broken or damaged vibromounts; Loose or vibrating sheet metal/housing; inadequate compartment clearances; Exhaust piping or air inlets/outlets not securely installed; No compartment sound insulation; Excessive vibration—engine/generator
Fix: Check and replace as necessary; Check and replace as necessary; Retighten screws; Check clearances; Inspect for loose parts; Install fireproof insulation; Check rotor, crankshaft, bearing, etc. (Disassembly of engine and/or generator may be required)
Starter does not work properly
Cause: Loose or corroded connections; Low battery output; Defective starter solenoid; Defective start/stop switch; Defective wiring; Defective starter
Fix: Clean and tighten loose connections; Check electrolyte level and specific gravity (batteries with filler caps only); Check starter solenoid. Replace starter solenoid, as necessary; Replace switch; Check wiring; Replace starter
Press start switch (Local or remote) Does engine crank?
Fix: No Is LED2 lit? Yes Is 15-amp controller fuse okay? No Replace circuit board (Defective board K3 normally open e Check condition/connections of K3 relay or K1 u Replace circuit board (Defective K3 relay)
Overheats
Cause: Improper cooling; Air cleaner clogged; Carburetor adjusted too lean; Faulty spark plug(s)
Fix: Check cooling system air flow; Clean or replace element; Adjust carburetor; Replace spark plug(s)
Operates erratically
Cause: Air cleaner clogged; Stale or bad fuel; Governor not properly adjusted or defective (Engine not operating at rated RPM); Fuel line restriction; Faulty spark plug(s); Carburetor adjustment wrong
Fix: Clean or replace element; Replace; Check engine speed using frequency meter or tachometer.; NOTE: For 60 Hz-1800 RPM; For 50 Hz-1500 RPM; Inspect fuel lines and tank. Check fuel pump pressure of 2-3.5 psi (14-24 kPa); Replace spark plug(s); Adjust carburetor
Low Oil Pressure Shutdown LOP
Lacks power
Cause: Governor not properly adjusted or defective (Engine not operating at rated RPM); Air cleaner clogged; Improper cooling; Engine overloaded; Stale or bad fuel; Fuel line restriction; Dirty fuel filter (gasoline fuel only); Carburetor adjustment wrong; Choke misadjusted or defective; Carbon buildup; Faulty spark plug(s); Defective ignition module
Fix: Check engine speed using frequency meter or tachometer.; NOTE: For 60 Hz-1800 RPM; For 50 Hz-1500 RPM; Clean or replace element; Check air flow cooling system; Reduce electrical load; Replace; Check fuel lines and tank; Replace fuel fitter; Adjust carburetor; Check and/or adjust; Clean cylinder heads; Replace spark plug(s); Test and/or replace coil

Compiled from service & troubleshooting documentation across every generator set that uses the Kohler M18 / M20.

Maintenance schedule

Item	Spec	Part #	Interval
Air filter	Paper Element	—	100 hr
Fuel filter	Replace the fuel filter every 500 hours of running time or when rough operation indicates an engine tune-up may be necessary.	993872	500 hr	Amazon eBay $110.25
Oil filter		8275513		Amazon eBay
Battery	Group 31 or equivalent	—	240 hr
Belt	KOHLER OE #994162	—	50 hr
Coolant	KOHLER OE #993873	993873	50 hr	Amazon eBay
Coolant filter		—
Oil	SAE 10W-30 or equivalent	—	50 hr
Spark plug	Service spark plugs as follows: Remove, examine, clean, file and replace if necessary.	—	500 hr

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Oil (new/overhauled engine)	Change	5 hr		First service — Initial break-in oil change
Foam precleaner	Clean	25 hr		Wash and reoil
Air cleaner	Clean	50 hr	6 mo	Replace if dirty
Battery electrolyte level	Check	50 hr	6 mo
Cooling fins and external surfaces	Clean	50 hr
LP collection pipe (LP liquid units)	Drain	50 hr	6 mo	Drain contaminants into suitable container
Lube oil filter	Replace	100 hr	12 mo	Replace every time oil is changed
Oil and filter	Change	50 hr		Per Oil Change Intervals table; 25 h without filter or for continuous/heavy duty
air cleaner	Check	50 hr	6 mo	Replace if dirty
collection pipe (LP liquid-fueled units)	Drain	50 hr		If equipped
lube filter	Replace	100 hr	12 mo	First service — 5 kW; replace at every oil change; initial after first five hours
Battery specific gravity	Test	100 hr	12 mo
Electrical connections	Inspect	100 hr	12 mo	Check and tighten
LP liquid withdrawal fuel filter	Inspect	100 hr		Inspected yearly or after every 100 hours
Mounting bolts and vibromounts	Inspect	100 hr	12 mo	Check and tighten
Paper air cleaner element	Clean	100 hr		Check condition; replace if dirty/bent/damaged
Spark arrestor	Clean	500 hr	24 mo
Spark plugs	Check	100 hr		Check condition/gap or replace
battery specific gravity	Check	100 hr	12 mo
liquid withdrawal LP fuel filter	Inspect	100 hr	12 mo	Yearly or every 100 hours
lube oil	Change	100 hr	12 mo	First service — Change oil initially after first five hours of operation
spark plugs	Replace	100 hr	12 mo	Service or replace; check condition every 100 hours
Stepper motor/throttle shaft coupling	Inspect	250 hr		Check for coupling wear
stepper motor/throttle shaft coupling	Check	250 hr		Check for wear
Compression	Check	500 hr	24 mo
Crankshaft splined insert	Lubricate	500 hr		Re-lubricate splines every 500 hours
Cylinder heads	Clean	500 hr	24 mo	Service after each 500 hours; every 250 hours if using leaded fuel
Cylinder heads and combustion chambers	Clean	500 hr		250 hours when leaded gasoline used
Fuel filter	Replace	500 hr
Starter motor drive	Lubricate	500 hr	12 mo	Every 500 hours or annually, whichever occurs first
Valve-tappet clearance	Adjust	500 hr	24 mo	After each 500 hours
Valve-to-tappet clearance	Check	500 hr		Engine must be cold
compression	Test	500 hr	24 mo	Check compression
cylinder heads	Other	500 hr		Service cylinder heads at authorized dealer; every 250 hours if leaded fuel used
cylinder heads	Replace	500 hr	24 mo	Service cylinder heads; 250 hours if leaded fuel
electrical connections	Check	500 hr	24 mo	Check and tighten
generator	Clean	500 hr	24 mo	Blow dust out of generator
mounting bolts and vibromounts	Check	500 hr	24 mo	Check and tighten
valve-tappet clearance	Check	500 hr	24 mo	Performed at an authorized Kohler service dealer/distributor

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Camshaft end play	.003/.013	in
Clearance	Camshaft to camshaft bearing running clearance	.0010/.0025	in
Clearance	Crankshaft end play	.002/.014	in
Clearance	Cylinder head maximum out of flatness	.003	in	measure between each cap screw hole
Clearance	Exhaust valve guide I.D. max wear limit	.007	in
Clearance	Exhaust valve minimum lift - zero lash	.274	in
Clearance	Exhaust valve minimum stem O.D.	.3088	in
Clearance	Float to float pin tower clearance	.010	in
Clearance	Intake valve guide I.D. max wear limit	.005	in
Clearance	Intake valve minimum lift - zero lash	.274	in
Clearance	Intake valve minimum stem O.D.	.3103	in
Clearance	Oil pump drive gear end play	.010/.029	in
Clearance	Oil pump shaft to crankcase running clearance	.0010/.0026	in
Clearance	Piston ring end gap - new cylinder bore	.010/.023	in
Clearance	Piston ring end gap - used cylinder bore	.010/.032	in
Clearance	Piston ring side clearance maximum	.006	in
Clearance	Valve guide reamer size	.3125	in
Gap	Electronic governor magnetic pickup air gap	0.040	in. (1.02 mm) +/- 0.005 in. (0.127 mm)
Gap	Governor magnetic pickup air gap	0.040 (0.005)	in. (1.02 mm, 0.127 mm)
Gap	Ignition module to magnet air gap	.008/.012	in	final range
Gap	Ignition module to magnet air gap	0.008-0.012	in.
Gap	Magnetic pickup air gap	0.040 in. (1.02 mm) + 0.005 in. (0.127 mm)	in. (mm)
Gap	Spark plug gap	0.035	in
Gap	Spark plug gap (LP gas)	0.018 in. (0.46 mm)	in. (mm)
Gap	Spark plug gap (gasoline)	0.025 in. (0.64 mm)	in. (mm)
Gap	Spark plug gap - LP gas	0.018	in. (0.46 mm)
Gap	Spark plug gap - gasoline	0.025	in. (0.64 mm)
Other	Air requirements - combustion	20	cfm (0.6 m3/min)
Other	Air requirements - cooling	340	cfm (9.6 m3/min)
Other	Battery charging system rated output	0-15	amps (regulated)
Other	Battery specific gravity (charge required below)	1.215	specific gravity	at 80°F (26.7°C) electrolyte temperature
Other	Battery specific gravity (fully charged)	1.260	specific gravity	at 80°F (26.7°C) electrolyte temperature
Other	Carburetor idle fuel needle preliminary setting	1 1/2	turns
Other	Carburetor main fuel needle preliminary setting	2 1/4	turns
Other	Carburetor preliminary idle fuel screw setting	1	turns out from bottomed
Other	Carburetor preliminary main fuel screw setting	2-1/2	turns out from bottomed
Other	Charge battery if specific gravity below	1.215	specific gravity	at 80 deg F (26.7 deg C)
Other	Choke adjustment above 10 deg F (-12.2 deg C), scribe-to-casting mark distance	5/16	in. (8 mm)
Other	Choke adjustment distance (above 10°F)	5/16 in. (8 mm)	in. (mm)
Other	Choke plate position	within 5 to 10 degrees of full open	degrees	at approximately 70°F (21°C)
Other	Choke plate position at approx. 70 deg F (21 deg C)	5 to 10 degrees of full open	degrees	approx. 70 deg F (21 deg C)
Other	Cranking current at 70 deg F (21 deg C)	100	amps	70 deg F (21 deg C)
Other	Derating - altitude above sea level	approximately 4.0% per 1000 ft. (300 m)	%
Other	Float drop	1-1/32	in
Other	Float level	11/64	in	plus or minus 1/32
Other	Free air opening	85	sq. in. (548 sq. cm)
Other	Fully charged battery specific gravity	1.260	specific gravity	at 80 deg F (26.7 deg C)
Other	Gasoline carburetor idle fuel needle preliminary setting	1 1/2	turns out
Other	Gasoline carburetor main fuel needle preliminary setting	2 1/4	turns out
Other	LP carburetor idle fuel screw setting	1/4	turn out
Other	LP carburetor main fuel valve preliminary setting	1	turn out (360 deg)
Other	LP idle fuel screw preliminary setting	1/4	turn
Other	LP main fuel valve preliminary setting	1	turn
Other	Maximum difference between cell specific gravities	0.01	specific gravity
Other	Minimum recommended clearance for vibration and cooling (front, side, top, rear)	0.6	in. (15.2 mm)
Other	Stator output voltage B1-B2 (separately excited)	12-15	vac	during cranking
Pressure	Compression minimum	90	psig	difference between cylinders less than 15%
Pressure	Crankcase vacuum	13 to 20	in H2O	engine at 3200 to 3600 RPM
Pressure	Engine oil pressure	30-40	psi (207-276 kPa)
Pressure	Engine oil pressure	30-40 psi (207-276 kPa)	psi (kPa)

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Ambient	Capacity	Notes
Engine oil	10W-30	API SF or SG			Multi-viscosity oil above 32 F (0 C) increases oil consumption and combustion deposits.
Engine oil	5W-20, 5W-30	API SF or SG
Engine oil	SAE 30 preferred; SAE 10W-30/10W-40 multiviscosity below 32F (0C)	API Service Class SF or SG		1.6 U.S. quarts	Add 1/2 U.S. pint when oil filter is replaced. Straight 30-weight preferred. 10W-30/10W-40 not recommended above 32F (0C).
Engine oil	SAE 30 straight-weight preferred (also 10W-30, 5W-20, 5W-30 per temperature chart)	API service class SF or SG		1.5 qts (L) with filter	Do not use synthetic oils during first five hours; do not mix brands; multi-viscosity oil above 32 deg F (0 deg C) increases oil consumption
Engine oil	SAE 30 straight weight preferred; 5W-20/5W-30 multi-viscosity permitted	API Service Class SF	-30°C to 40°C		Do not use synthetic oils during first five hours; multi-viscosity increases oil consumption above 32°F (0°C)
Engine oil	SAE 30 (straight weight preferred)	API SF or SG	above 0°C	1.5 qt	Base oil type selection on air temperature at time of operation. Do not use synthetic oils during first five hours. Do not mix different brands of oils.
Fuel	LP Gas (vapor or liquid withdrawal)	NFPA58 Section 3-6.4			LP vapor inlet pressure 4-6 oz. (7-11 in. water column); LP liquid withdrawal 50 psi
Fuel	LP vapor gas inlet pressure 7-11 in. water column, 4-6 oz per sq. in.	LP liquid withdrawal inlet pressure 50 psi			Liquid withdrawal fuel must be blended for season and geographic location
Fuel	LP vapor or LP liquid withdrawal gas blended for the season and geographic location
Fuel	Regular grade unleaded gasoline, pump octane 87 or higher (90 research octane min.)				Gasohol max 10% ethanol allowed; never methanol; oil must not be mixed with fuel
Fuel	Regular unleaded gasoline, 87 octane minimum (90 research rating method)	Gasohol with no more than 10% ethanol permitted			Use fresh gasoline; never use gasoline with methanol
Fuel	Unleaded gasoline, 87 octane (90 research rating method minimum)				Gasohol containing no more than 10% ethanol may be used; never use methanol or more than 10% ethanol. Do not mix oil with the fuel. Use fresh gasoline.
Fuel	Unleaded gasoline, pump sticker octane 87 or higher (90 octane minimum Research method)	Gasohol up to 10% ethyl alcohol approved; MTBE up to 15% by volume approved			Do not add oil to gasoline. Do not use gasoline left over from previous season.
Grease	Kohler electric starter drive lubricant (Part No. 52 357 01); Dow Corning G-N Metal Assembly Paste or #77 Assembly Paste for splines				Loctite No. 271 on starter stop nut threads; Loctite No. 592 Teflon sealant on Oil Sentry switch threads
Grease	Petroleum jelly or other nonconductive grease				Coat battery terminals after cleaning and reconnection

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Adjust Carburetor adjustment

⚠ Do not force tapered adjusting needles

Tools: Tachometer, Screwdriver

Stop engine; turn adjusting needles in clockwise until lightly bottomed.
Set preliminary settings: main fuel 2-1/2 turns, idle fuel 1 turn out.
Run engine at half throttle 5-10 minutes to warm up.
Final main fuel: set needle midway between rich and lean settings.
Final idle fuel: set needle using same procedure; idle speed not to exceed 1500 RPM.
Set idle speed to 1200 RPM (plus or minus 75) with idle speed screw.

Adjusting Valve Clearance adjustment

Tools: feeler gauge, valve grinding tools

Stop and cool engine to ambient temperature.
Rotate flywheel and observe valve movement to find cylinder at TDC.
Measure valve-to-tappet clearance with flat feeler gauge.
Rotate flywheel 360 degrees; measure remaining cylinder.
Grind valve stems if clearance insufficient; replace valves if excessive.

Check Valve-to-Tappet Clearance adjustment

⚠ Piston must be at TDC of compression stroke to measure clearance

Tools: Flat feeler gauge

Remove air cleaner, valve covers, breather, and spark plugs.
Rotate flywheel and observe tappets; measure clearance on cylinder with no movement.
Measure with a flat feeler gauge (engine cold).
Rotate flywheel 360 degrees and measure remaining cylinder.
If clearance too small, grind valve stems; if too large, replace valves.

Choke Adjustment Above 10 deg F (-12.2 deg C) adjustment

Tools: screwdriver, scribe

Scribe mark on choke black cover where casting mark meets it.
Loosen two choke adjusting screws.
Rotate choke cover counterclockwise toward leaner setting.
Tighten screws when scribe-to-casting distance is 5/16 in. (8 mm).

Choke Adjustment for Operation above 10°F (-12.2°C) adjustment

Make a scribe mark on the black plastic cover where the choke casting mark meets it.
Loosen the two choke adjusting screws and rotate choke cover counterclockwise toward leaner setting.
When distance between scribe mark and casting mark is 5/16 in. (8 mm) tighten the two adjusting screws.

Choke Adjustment for Operation below 10°F (-12.2°C) adjustment

⚠ If not previously adjusted, leave as factory set.

Loosen the two choke adjusting screws and rotate choke cover clockwise (opposite arrow on choke).
When the scribe mark on the black plastic cover and the choke casting mark line up, tighten the two adjusting screws.

Electronic Governor Adjustment adjustment

⚠ Do not use speed adjustment pot to check the overspeed cutout point.

Tools: Frequency meter

Check alignment of governor actuator shaft to carburetor throttle shaft.
Attach frequency meter to AC output leads and run to normal temperature.
Adjust speed pot to obtain full load speed of 60 Hz or 50 Hz.
With no load, turn gain pot 1/8 turn counterclockwise until stable.
Apply rated load and observe frequency reading.
Remove load and observe frequency returns to speed adjustment value.
Check overspeed cutout point by manually moving throttle shaft clockwise.
Turn overspeed pot as necessary to obtain desired cutout point.

Gasoline Carburetor Main and Idle Fuel Adjustment adjustment

⚠ Do not force the tapered adjusting needles or needle and seat damage will occur.

Tools: screwdriver

Stop engine; turn main and idle needles in clockwise until lightly bottomed.
Back main needle out 2 1/4 turns and idle needle 1 1/2 turns.
Start engine and run at half load 5-10 minutes to warm.
Run at 3/4 to full load; turn main needle in until engine runs roughly.
Turn main needle out 1/4 turn richer than lean limit.
Set idle fuel needle using same procedure.

Gasoline Carburetor Main and Idle Fuel Mixture Adjustment adjustment

⚠ Damage to needles and seats will result if the needles are forced.

Stop engine and turn main fuel and idle fuel adjusting needles in until they bottom lightly.
Back out main fuel needle 2 1/4 turns and idle fuel needle 1 1/2 turns.
Start engine and run at half-load for 5-10 minutes to warm up.
At 3/4 to full load, turn main fuel needle in until engine does not operate smoothly; note position.
Turn the main fuel needle out 1/4 turn.
Set idle fuel needle using the same procedure.

Gasoline Choke Adjustment adjustment

Scribe mark where choke casting mark meets black plastic cover.
Loosen the two choke adjusting screws.
Above 10 F (-12.2 C): rotate cover counterclockwise to leaner until 5/16 in. (8 mm) from mark.
Below 10 F (-12.2 C): rotate cover clockwise until marks line up.
Tighten the two adjusting screws.

LP Carburetor Adjustment adjustment

⚠ Improper rich adjustment causes vaporizer malfunction and excess fuel consumption.

Tools: screwdriver

Turn main fuel valve clockwise until lightly bottomed; back out 1 turn.
Warm engine and run at rated rpm under full load.
Turn main valve in until engine slows (lean); out until full speed regained.
Stop engine; turn idle fuel screw fully in, then back out 1/4 turn.

LP Gas Carburetor Main Fuel Mixture Adjustment adjustment

Turn MAIN FUEL valve clockwise until it bottoms lightly (do not force), then back out 1 turn.
With engine warm at rated rpm under full load, turn MAIN FUEL valve in until engine slows (lean).
Turn valve out until engine regains full speed (about 1/8 turn).

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

Voltage	Phase	Connection	Leads	Notes
110	1	2-wire, 4-lead reconnectable	L1	50 Hz; use single-pole circuit breaker.
110	1	3-wire, 4-lead reconnectable	LO-L1, LO-L2	50 Hz; LO is neutral.
110/220	1	3-wire, 4-lead reconnectable	L1-L2	50 Hz; factory two-pole circuit breaker required.
110/220	3	4-wire delta, 12-lead reconnectable		50 Hz
110/220 volt	1	3 Wire (12-lead stator)		50 Hz
110/220 volt	3	4 Wire Delta (12-lead stator)		50 Hz
120	1	2-wire, 4-lead reconnectable	L1	60 Hz; use single-pole circuit breaker.
120	1	3-wire, 4-lead reconnectable	LO-L1, LO-L2	60 Hz; LO is neutral. Factory two-pole or (2) 1-pole circuit breakers; jumper lead used.
120 Volt	1	View A—120 Volt, 3 Wire	L1, L2, LO (Neutral), Ground	Factory two-pole or (2) 1-pole circuit breakers; jumper lead on line side; LO-L1 120 Volt, LO-L2 120 Volt (60 Hz)
120 Volt	1	View B—120 Volt, 2 Wire	L1, LO (Neutral), Ground	1-pole circuit breaker; LO-L1 120 Volt (60 Hz)
120 Volt (60 Hz) / 110 Volt (50 Hz)	single	L0-L1	L0, L1	View A - 120 Volt 3 wire (factory two-pole or (2) 1-pole circuit breakers, jumper lead on line side)
120 Volt (60 Hz) / 110 Volt (50 Hz)	single	L0-L2	L0, L2	View A - 120 Volt 3 wire
120/208 or 110/190	3	4-wire low wye, 12-lead reconnectable		50 Hz
120/208 or 139/240	3	4-wire low wye, 12-lead reconnectable		60 Hz
120/208 volt or 110/190 volt	3	4 Wire Low Wye (12-lead stator)		50 Hz
120/208 volt or 139/240 volt	3	4 Wire Low Wye (12-lead stator)		60 Hz
120/240	1	3-wire, 4-lead reconnectable	L1-L2	60 Hz; jumper lead not used; MUST use factory two-pole circuit breaker. L1 and L2 must never be connected together.
120/240	3	4-wire delta, 12-lead reconnectable		60 Hz
120/240 Volt	1	View C—120/240 Volt, 3 Wire	L1, L2, LO (Neutral), Ground	Factory two-pole circuit breaker; leads L1 and L2 are different phases and must never be connected together
120/240 volt	1	3 Wire (12-lead stator)		60 Hz
120/240 volt	3	4 Wire Delta (12-lead stator)		60 Hz
220/380	3	4-wire high wye, 12-lead reconnectable		50 Hz
220/380 volt	3	4 Wire High Wye (12-lead stator)		50 Hz
240 Volt (60 Hz) / 220 Volt (50 Hz)	single	L1-L2	L1, L2	View C - 120/240 Volt 3 wire (two-pole circuit breaker required; jumper lead removed)
277/480	3	4-wire high wye, 12-lead reconnectable		60 Hz
277/480 volt	3	4 Wire High Wye (12-lead stator)		60 Hz

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Parts cataloged across the Kohler M18 family

Part #	Description	Category
227647	Air filter	Air filter
228269	Air filter	Air filter
278612	Element, air cleaner	Air filter
994162	Air Filter	Air filter
52 221 01	Starter brush kit (four replacement brushes and springs)	Brush
52 012 07	Camshaft for engines with Serial No. 1816500646 and earlier	Camshaft
52 012 08	Camshaft for engines with Serial No. 1816500656 and later	Camshaft
82 755 09	Camshaft kit containing the 52 012 08 camshaft and 52 019 02 tappets (4)	Camshaft
F-239563	Controller Circuit Board	Controller circuit board
993873	Coolant	Coolant filter
FA-277000-B	Deicing Module (includes high-limit thermostat and heater)	Deicing module
993872	Fuel Filter	Fuel filter
25 757 14	Bushing, throttle shaft	Gasket
25 757 21	Ball, choke shaft	Gasket
278320	Exhaust Gasket	Gasket
52 050 02	Oil Filter	Oil filter
994216	Oil Filter	Oil filter
92 755 09	Oil relief valve repair kit containing a new spring, check ball and sleeve	Oil relief valve kit
25 757 01	Carburetor Repair Kit	Service part / kit
25 757 02	Carburetor Repair Kit	Service part / kit
25 757 03	Float Repair Kit	Service part / kit
278621	Spark Arrestor	Service part / kit
48 755 23	11 tooth insert	Service part / kit
82 755 02	9 tooth insert	Service part / kit
8275513	Camshaft and four tappets kit	Service part / kit
2575709	Float Assembly Kit No. 25 757 09 (For WHG-Serles Carbs.)	Repair kit
2575711	Carburetor Repair Kit No. 25 757 11 (For WHG-Series 1")	Repair kit
11795	handle and appropriate seal driver	Seal
51 132 02	Spark Plug	Spark plug
82 755 24	Carburetor Baffle Kit	Spark plug
52 019 02	Tappets for engines with Serial No. 1816500656 and later	Tappet
52 019 03	Tappets for engines with Serial No. 1816500646 and earlier	Tappet
K01017	Tool for installing Welch plugs	Tool
K01018	Tool for removing Welch plugs	Tool

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Common questions

What is the oil capacity of the Kohler M18 / M20?

The Kohler M18 / M20 engine has an oil capacity of 1.6 liters.

What is the displacement of the Kohler M18 / M20?

The Kohler M18 / M20 has a displacement of 42.18 liters with 2 cylinders.

Which generators use the Kohler M18 / M20 engine?

The Kohler M18 / M20 powers 5 generator set(s), including Kohler 4 and 5 kW, Kohler 4CFKM, Kohler 4CKM, Kohler 5CKM, Kohler TP-5393.

How often should you change the oil in the Kohler M18 / M20?

The Kohler M18 / M20 oil change interval is every 50 hours.

What is a common problem with the Kohler M18 / M20 engine?

A commonly reported issue on generators using the Kohler M18 / M20 is: Will not start. Cause: Out of fuel, Clogged fuel filter, Air cleaner clogged, Faulty spark plug, Shorted or open ignition coil, Faulty ground, Loose spark plug wire connection, Weak or dead battery, Choke adjustment wrong. Fix: Replenish, Replace, Clean or replace, Replace or regap spark plugs, Replace, Clean and retighten, Reconnect and/or tighten, Recharge or replace, Adjust.