Kohler 8.5RES — Specs, Engine, Parts & Maintenance

Service parts for the 8.5RES

Grouped by system, with how many of each the parts manual calls for.

Air intake

1 required

ADV-6823-AAir filtersee priceAmazon

Oil system

2 required

12 050 01Oil filtersee priceAmazon

5810321Oil$170.00eBay

Electrical

1 required

53ABBatterysee priceAmazon

Ignition

1 required

12 132 02-SSpark plugfind

Prices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.

Specifications

Fuel	natural gas or propane (LP) vapor
Frequency	60.0 Hz
Standby power	8 kW
Standby kVA	8
Prime power	7 kW
Controller	ADC 2100, ADC-RES, ADC-RES (Advanced Digital), Advanced Digital, Advanced Digital (ADC 2100), Advanced Digital Features
Oil capacity	1.9 L
Alternator	2F4 (2-pole, Class Class 180 (H) insulation)
Voltage options	246/242 V
Phase	1
Rated current	35 A
Power factor	1.0
Circuit breaker	40 A
Battery cranking	525 minimum at -18 C (0 F) CCA
Battery voltage	12 VDC V
Battery quantity	1
Dimensions (L×W×H)	42×30×32 mm
Dry weight	182 kg
Sound level	65.0 dBA @ 23 ft m

Engine

Kohler CH20

Oil capacity	1.9 L
Coolant capacity	0.0 L
Displacement	8.5 L
Aspiration	air-cooled
Rated speed	3600 rpm

Same engine, other brands

2 brands

The Kohler CH20 in this set also powers 2 generator sets sold under 2 other brands. Service parts and maintenance intervals for the engine are shared; enclosure, alternator, controller and ratings are not.

Brand	Models
AlphaGen	PN-6x
Cummins/Onan	8.5RMY

Maintenance & consumables

for the Kohler CH20

Item	Spec	Part #	Interval
Air filter	Air Filter, Spark Plug Location	ADV-6823-A		Amazon eBay
Fuel filter	Fuel Filter	—	8 hr
Oil filter	Oil filter	12 050 01	200 hr	Amazon eBay KuduParts $11.00 FridayParts $33.98
Battery	12-volt negative ground engine electrical system	53AB	12 hr	Amazon eBay
Belt	Belt	—	500 hr
Coolant	Cooling System	—
Coolant filter	Inspect and clean the oil cooler	—	500 hr
Oil	5810321	5810321	50 hr	Amazon eBay $170.00
Spark plug	0.76 mm (0.030 in.)	12 132 02-S	500 hr	buy

Service intervals

Item	Action	Hours	Months	Notes
Oil level	Check	8 hr		First service — Lubrication; 8 hours or before use
Air cleaner and precleaner	Clean	100 hr	12 mo	Yearly or 100 Hrs.; service more often in dusty areas
Air cleaner and precleaner (8.5/12RES)	Replace	100 hr	12 mo	Yearly or 100 hours; replace as necessary
Air cleaner and precleaner service	Clean	100 hr	12 mo	Yearly or 100 hr.; service more frequently in dusty areas
Air cleaner and precleaner service	Replace	100 hr	12 mo
Air cleaner and precleaner service (8.5/12 kW)	Replace	100 hr		Yearly or 100 hours; service more frequently under dusty/dirty conditions
Air cleaner service	Replace	100 hr	12 mo	Engine and Mounting; Yearly or 100 hours; replace as necessary (R)
Change oil	Replace	100 hr	12 mo	Yearly or 100 hr.
Crankcase oil	Change	100 hr	12 mo	Yearly or 100 Hrs.
Engine oil	Change	100 hr	12 mo	Lubrication; Yearly or 100 hours
Oil cooler	Clean	100 hr	12 mo	Yearly or 100 hours; 17/18 kW models
Oil cooler	Inspect	100 hr		Yearly or 100 hours (17/18 kW models)
Oil cooler (17/18RES)	Clean	100 hr	12 mo	Yearly or 100 hours; inspect and clean
Air cleaner service	Clean	150 hr		Yearly or hours shown; 17/18 kW models
Air cleaner service (17/18 kW)	Replace	150 hr		Yearly or 150/300 hours
Change oil	Change	150 hr	12 mo	Yearly or 150 hours (17/18 kW models)
Engine oil (17/18RES)	Change	150 hr	12 mo	Yearly or 150 hours
Oil	Change	150 hr		Yearly or 150 hours; 17/18 kW models
Oil filter (17/18RES)	Replace	150 hr	12 mo	Yearly or 150 hours
Spark plugs	Clean	150 hr		Yearly or hours shown; 17/18 kW models
Spark plugs (17/18 kW)	Replace	150 hr		Yearly or 150/300 hours
Oil filter	Replace	200 hr	12 mo	Yearly or 200 hours; 8.5/12 kW models
Oil filter(s)	Replace	200 hr	12 mo	Yearly or 200 Hrs.
Replace filter	Replace	200 hr	12 mo
Replace filter (oil filter)	Replace	200 hr		Yearly or 200 hours (8.5/12 kW models)
Replace filter(s)	Replace	200 hr	12 mo	Yearly or 200 hr.
Air cleaner service	Change	300 hr		Yearly or hours shown; 17/18 kW models
Spark plugs	Check	300 hr	12 mo	Yearly or 300 hours; 8.5/12 kW models
Spark plugs	Replace	500 hr	12 mo	Yearly or hours shown; 17/18 kW models
Spark plugs (8.5/12 kW)	Replace	300 hr		Yearly or 300 hours
Spark plugs (8.5/12RES)	Check	300 hr	12 mo	Yearly or 300 hours
Crankcase breather	Change	500 hr	12 mo	Lubrication; Yearly or 500 hours
Crankcase breather hose	Check	500 hr	12 mo	Yearly or 500 hours; 8.5/12 kW models
Crankcase breather hose	Clean	500 hr	12 mo
Crankcase breather hose	Other	500 hr	12 mo	Yearly or 500 hr.; follow engine manufacturer's maintenance manual
Replace spark plugs	Replace	500 hr
Replace stepper motor coupling and bushing	Replace	500 hr		authorized distributor/dealer only
Resistance readings of windings with insulation tester (Megger)	Test	500 hr	36 mo	3 yr.; with SCR assembly or rectifier and load leads disconnected
Stepper motor coupling and bushing	Replace	500 hr	36 mo	Engine and Mounting; 500 hours
Wire-cable insulation breakdown	Inspect	500 hr	36 mo	3 Years or 500 Hrs.

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
Gap	Magnetic pickup air gap	0.5	mm (0.020 in.)
Gap	Spark Plug Gap 12/17/18RES	0.76	mm (0.030 in.)
Gap	Spark Plug Gap 8.5kW	0.51	mm (0.020 in.)
Gap	Spark plug gap	0.51	mm (0.02 in.)
Gap	Spark plug gap	0.7--0.8	mm (0.028--0.030 in.)
Gap	Spark plug gap	0.76	mm (0.030 in.)
Gap	Spark plug gap	0.8--0.9	mm (0.03--0.04 in.)
Gap	Spark plug gap	0.89	mm (0.035 in.)
Gap	Spark plug gap	0.9--1.0	mm (0.036--0.04 in.)
Other	Battery electrolyte specific gravity (full charge)	1.260		electrolyte at 26.7 C (80 F)
Other	Battery specific gravity (charge threshold)	1.215		electrolyte at 26.7 C (80 F)
Other	Battery specific gravity variation (charge threshold)	0.01		cell-to-cell variation
Other	Brush length, new	19.05	mm (0.75 in.)	new
Other	Compression ratio	8.5:1
Other	Compression ratio	9.0:1
Other	Fuel system leak test pressure	6-8 ounces per square inch (10-14 inches water column)	oz/in²	LPG vapor or natural gas system
Other	Insulation resistance indicating good stator/rotor	500	kOhms (1/2 megohm) or higher
Other	Megohmmeter test voltage (stator/rotor to ground)	500	VDC
Other	No load and full load frequency tolerance	0.4	Hz	rated generator frequency
Other	Overfrequency shutdown	110	% of system frequency setpoint for more than 5 seconds	10 second inhibit after start
Other	Overfrequency shutdown threshold	110	% of system frequency setpoint	more than 5 seconds, active 10s after start
Other	Underfrequency shutdown	90	% of nominal system frequency for more than 5 seconds	10 second inhibit after start
Other	Underfrequency shutdown threshold	54	Hz	more than 5 seconds (or below 56.5 Hz for more than 60 seconds)
Pressure	Engine oil pressure	172--241	kPa (25--35 psi)
Pressure	Fuel regulator inlet gas pressure	7-11	in. (4-6 oz.)	at fuel regulator inlet
Pressure	Fuel supply pressure	1.7--2.7	kPa	(7-11 in. H2O)
Pressure	Fuel supply pressure at secondary regulator inlet	178--280	mm water column (7--11 in. H2O) or 1.7--2.7 kPa (4--6 oz./in.2)	generator set running at rated load
Pressure	Gas fuel system leak test pressure	6--8	oz/in2	(10-14 inches water column), soap and water solution
Pressure	LP supply pressure	1.7--2.7	kPa (7--11 in. water column)
Pressure	Low oil pressure shutdown	24.1	kPa ±13.8 kPa (3.5 psi ±1.5 psi)
Pressure	Low oil pressure shutdown	24.1 ±13.8	kPa	(3.5 psi ±1.5 psi)
Pressure	Natural gas supply pressure	1.2--2.7	kPa (5--11 in. water column)
Pressure	Secondary regulator maximum inlet pressure	2.7	kPa (6 oz./in.2) or 280 mm (11 in.) water column
Resistance	Brush resistance	0.1--0.2	ohms (without meter lead resistance)
Resistance	Coolant temperature sensor (CTS) resistance	180--200	ohms	at 100 C (212 F)
Resistance	Coolant temperature sensor (CTS) resistance	2100--2500	ohms	at 30 C (86 F)
Resistance	Coolant temperature sensor resistance at 100 C (212 F)	180--200	ohms	100 C
Resistance	Coolant temperature sensor resistance at 30 C (86 F)	2100--2500	ohms	30 C
Resistance	Magnetic pickup resistance across QCON1 and QCON2	1.3--1.9	kOhm
Resistance	Resistance through the brushes	0.1--0.2	ohms	without meter lead resistance
Resistance	Rotor resistance	4.0	ohms, cold	cold
Resistance	Rotor resistance	4.2	ohms, cold	cold
Resistance	Rotor resistance, cold	4.0	ohms	cold
Resistance	Starter relay coil resistance	5--7	ohms
Resistance	Stator resistance leads 1-2, 3-4	0.07	ohms, cold	cold
Resistance	Stator resistance leads 1-4, 2-5, 3-6, 7-10, 8-11, 9-12	0.18	ohms, cold	cold
Resistance	Stator resistance leads 11-44	0.14	ohms, cold	cold
Resistance	Stator resistance leads 55-66	0.15	ohms, cold	cold
Resistance	Stator resistance leads 55-66	0.70	ohms, cold	cold
Resistance	Stator resistance, leads 1-2, 3-4	0.07	ohms	cold
Resistance	Stator resistance, leads 11-44	0.14	ohms	cold
Resistance	Stator resistance, leads 55-66	0.70	ohms	cold
Resistance	Stepper motor coil resistance per half coil	38.5	ohms
Speed	Crank cycle	15	seconds crank and 15 seconds off, 3 attempts	starting
Speed	Crank cycle	15 seconds crank and 15 seconds off, 3 attempts	seconds
Speed	Cut-in frequency	47.5	Hz	50 Hz units
Speed	Cut-in frequency	57.5	Hz	60 Hz units
Speed	Cut-in frequency, 50 Hz	47.5	Hz	50 Hz models
Speed	Cut-in frequency, 60 Hz	57.5	Hz	60 Hz models
Speed	Engine speed, full load (mechanical governor)	3600	RPM (60 Hz)	full load

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	5W-30	API SG, SH, or SJ synthetic			Synthetic oil recommended
Engine oil	Synthetic oil, API Service Class SG or higher	API SG or higher		1.9 L (2.0 qt.)	8.5RES capacity with filter; see engine oil selection chart for viscosity (5W-20, 5W-30, 10W-30)
Engine oil	5W-20, 5W-30	API Service Class SG or higher, synthetic	-30°C to 10°C		Engine Oil Selection chart; use synthetic oil
Engine oil	10W-30	API Service Class SG or higher, synthetic	-20°C to 40°C		Engine Oil Selection chart; use synthetic oil
Engine oil	API Service Class SG, SH, or SJ synthetic oil	API	20°C to 4°C	1.9 L (2.0 qt.)	10W-30 for one range; 5W-20/5W-30 shown to -20C
Fuel		LP gas or natural gas			Minimum supply pressure 7--11 in. H2O (4--6 oz./in.2); multi-fuel system field convertible
Fuel	LP gas or natural gas				LP/natural gas minimum supply pressure 7--11 in. H2O (4--6 oz./in.2)
Fuel	LP vapor				Nominal fuel rating 2500 Btu/ft3 (93 MJ/m3); supply pressure 1.7--2.7 kPa (7-11 in. H2O); LP vapor conversion factors: 8.58 ft3 = 1 lb., 36.39 ft3 = 1 gal.
Fuel	LPG				Fuel supply pressure 1.7-2.7 kPa (7-11 in H2O); nominal fuel rating 2500 Btu/ft3 (93 MJ/m3); supply inlet 1/2 NPT
Fuel	Natural Gas				Fuel supply pressure 1.3-2.7 kPa (5-11 in H2O) for 8.5/12RES, 1.7-2.7 kPa (7-11 in H2O) for 18RES; nominal fuel rating 1000 Btu/ft3 (37 MJ/m3); supply inlet 1/2 NPT
Fuel	Natural gas				Nominal fuel rating 1000 Btu/ft3 (37 MJ/m3); supply inlet 1/2 NPT; supply pressure 1.7--2.7 kPa (7-11 in. H2O)
Fuel	Natural gas or propane (LP) vapor	Field-convertible multi-fuel; CARB emission certified			Clean-burning natural gas or propane (LP) vapor; air-cooled engine, no liquid coolant
Other	Bicarbonate of soda (baking soda) and water solution				Battery acid cleanup: 500 g (1 lb.) bicarbonate of soda to 4 L (1 gal.) water; also used to clean battery and cables
Other	Petroleum jelly, silicone grease, or other nonconductive grease				Coat battery terminals after reconnecting cables

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

Fault codes

Code	Name	Meaning	Severity	Action
AF	Auxiliary fault input shutdown	Shutdown initiated by pushing the emergency stop switch (TRES models only). Not used on RES models.	Shutdown	Check the position of the emergency stop button. (TRES models only)
CC	Crank cycle
CO-3		Fault displayed if the CO parameter is set incorrectly	Shutdown
CO-6		Fault displayed if the CO parameter is set incorrectly	Shutdown
HB	High battery voltage warning	Fault code is displayed if the engine starting battery voltage rises above 16 VDC for more than 30 seconds when the engine is running. Not operative during the engine crank cycle; does not inhibit engine starting. Clears when the battery voltage returns to an acceptable level.	Warning	Check the battery rating and condition; check battery charger operation.
HE	High engine temperature shutdown	Shutdown occurs if the engine coolant temperature exceeds the maximum temperature for more than 5 seconds. This protective feature becomes active after the engine reaches the crank disconnect speed.	Shutdown	Check for blocked air inlets and exhaust outlets.
LB	Low battery voltage warning	Fault code is displayed if the engine starting battery voltage falls below 11 VDC for more than 30 seconds when the engine is not running. Not operative during the engine crank cycle; does not inhibit engine starting. Clears when the battery voltage returns to an acceptable level.	Warning	Check the battery rating and condition; check battery charger operation; charge or replace battery.
LCL	Low coolant level	Not used on air-cooled models.	Shutdown
LOC	Loss of coolant	Not used on air-cooled models.	Shutdown
LOP	Low oil pressure shutdown	Shutdown occurs if low oil pressure exists for more than 5 seconds; active 30 seconds after crank disconnect speed. Does not protect against low oil level.	Shutdown	Check for leaks in the lubrication system. Check the oil level and add oil if the level is low.
OC	Overcrank shutdown	Shutdown occurs after 3 unsuccessful starting attempts. The crank cycle is set for three starting attempts of 15 seconds cranking and 15 seconds rest. The generator set also shuts down on OC if no engine rotation is sensed during cranking; shuts down 3 seconds after the fault is detected (locked rotor).	Shutdown	Check the fuel supply, spark plug, and battery. Check for loose connections. Contact an authorized distributor/dealer if the problem continues.
OF	Overfrequency shutdown	Shutdown when governed frequency exceeds 110% of system frequency setpoint for more than 5 seconds; active 10 seconds after engine start.	Shutdown	Contact an authorized distributor/dealer for service if the problem continues.
OS	Overspeed shutdown	Shutdown occurs if the engine speed exceeds 115% of the normal running speed for more than 1 second.	Shutdown	Contact an authorized distributor/dealer for service if the problem continues.
OU	Overvoltage shutdown	Shutdown occurs if voltage exceeds 120% of system nominal voltage for more than 2 seconds.	Shutdown	Contact an authorized distributor/dealer for service if the problem continues.
SCF0	Software Communication Fault 0	Indicates a software or communication problem within the controller.	Shutdown	Replace the controller.
UF	Underfrequency shutdown	Shutdown when governed frequency falls below 90% of nominal system frequency for more than 5 seconds; active 10 seconds after engine start. (ADC-RES: below 54 Hz.)	Shutdown	Reduce the load and restart the generator set; contact distributor/dealer if problem continues
UU	Undervoltage shutdown	Shutdown occurs if voltage falls below 80% of nominal system voltage for more than 10 seconds.	Shutdown	Reduce the load and restart the generator set; contact distributor/dealer if problem continues

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

Procedures

ADC-RES Controller Configuration (Cn setting) adjustment

⚠ The controller automatically exits configuration mode without saving changes after about 1 minute if no buttons are pressed.

Enter the configuration mode while the engine is not running by following the Figure 26 sequence.
Step through the parameters to the communication setting Cn parameter.
Use the up and down arrow buttons to change the Cn setting to Cn01, if necessary.
Press to SAVE CHANGES (YES) before exiting the configuration mode.
Move the generator set master switch to OFF/RESET.

Controller Configuration adjustment

⚠ Be sure to save the new settings immediately before exiting the configuration mode; changes are lost if the controller times out (about 1 minute).

Hold the Select button and move the master switch to RUN to enter configuration mode.
Press the down arrow key then the up arrow key 3 times to enter configuration mode (password).
Set the voltage/frequency parameter Uu for the model.
Set the unit configuration parameter Uc (marine, standby, mobile).
Set the engine type parameter Ec.
Press the up arrow at the Adnc display to enter advanced configuration mode.
Set the engine data input type Ed.
Set the battery voltage Bt (12 or 24 VDC).
Set the communications parameter Cn.
Enter save mode and save your settings before exiting.

Frequency Adjustment Procedure adjustment

⚠ Hazardous voltage. Operate the generator set only when all guards and electrical enclosures are in place.

Tools: frequency meter

Open the generator set line circuit breaker.
Attach a frequency meter to the AC output leads.
Start and run the generator set until normal operating temperature (at least 10 minutes).
Use the ADC controller to adjust the electronic governor speed (parameter 4P) for 60 Hz (or 50 Hz).
Check stability with no load; decrease gain (parameter 5P) until stable if speed hunts or surges.
Repeat steps 4 and 5 to obtain rated frequency and stable operation.
Save the settings.
Apply rated load and observe frequency; no load and full load frequencies should be within 0.4 Hz of rated.
Check for hunting and surging at full load; increase gain until engine hunts, then decrease in small steps.
Remove the load and observe frequency; repeat step 4 if frequency changed.

Fuel Conversion Procedure (Models with Fuel Block) adjustment

⚠ Explosive fuel vapors. Use extreme care when handling, storing, and using fuels.

Disable genset: master switch OFF, disconnect battery charger, disconnect battery negative lead first.
Turn off fuel supply.
Remove hose clamp and fuel hose from hose fitting in the fuel metering valve.
Remove hose fitting from the natural gas outlet port.
Remove plug from LP port; clean, apply pipe sealant, install plug into natural gas port.
Clean hose fitting, apply pipe sealant, install fitting into LP port.
Slide hose onto fitting and secure with clamp.
For 12 kW models: connect DSAI leads together for natural gas (disconnect for LP).
Connect and turn on new fuel supply; reconnect battery negative last; reconnect battery charger.
Start genset and check for leaks using a gas leak detector.

Fuel Conversion Procedure (natural gas to LP vapor) adjustment

⚠ Do not adjust the factory-sealed fuel-metering adjustments on the fuel block.

⚠ Explosive fuel vapors can cause severe injury or death.

⚠ Accidental starting can cause severe injury or death.

Tools: Gas leak detector

Place the master switch in OFF, disconnect battery charger power, disconnect battery (negative lead first), and turn off fuel supply.
Remove the hose clamp and fuel hose from the hose fitting in the fuel block.
Remove the hose fitting from the natural gas outlet port in the fuel block.
Remove the plug from the LP port, clean it, apply fresh pipe sealant, and install it into the natural gas outlet port.
Clean the hose fitting, apply fresh pipe sealant to the threads, and install it into the LP port.
Slide the hose onto the fitting and secure it with the clamp.
For 12RES only: connect the DSAM leads together for natural gas (disconnect for LP vapor).
Connect and turn on the new fuel supply; recheck the master switch is OFF.
Reconnect the battery (negative lead last) and reconnect battery charger power.
Start the generator set by moving the master switch to RUN and check for leaks with a gas leak detector.
Move the generator set master switch to the AUTO position.

Fuel Metering Valve Adjustment Procedure adjustment

⚠ Adjusting fuel metering valves on emission-certified gensets may void the emission certification. Only trained authorized technicians may adjust.

Tools: Digital voltmeter (DVM), UEGO oxygen sensor service kit GM29385, Load bank

Disable genset (master switch OFF, disconnect battery charger).
Remove oxygen sensor plug from exhaust manifold and install oxygen sensor.
Connect oxygen sensor to engine starting battery, control module, and voltmeter.
Reconnect battery charger, start genset, and run to normal operating temperature.
Apply rated load; measure oxygen sensor output voltage (potential to ground).
Adjust fuel metering valve to obtain specified oxygen sensor output.
Seal metering valve adjustment screws with thread sealant.
Remove load and cool genset 5-10 minutes; stop genset.
Disconnect battery negative lead first; allow exhaust to cool.
Remove oxygen sensor and reinstall exhaust plug with antiseize; reconnect battery negative lead last and battery charger.

Mechanical Governor Arm Adjustment Procedure adjustment

⚠ Accidental starting can cause severe injury or death.

Tools: Nail

Make sure throttle linkage is connected to governor arm and carburetor throttle lever.
Loosen the hex nut holding the governor lever to the cross shaft.
Move governor lever toward carburetor as far as it will go (wide open throttle) and hold.
Insert a nail into the hole in the cross shaft and rotate the shaft counterclockwise as far as it will turn; tighten hex nut and remove nail.

Output Voltage and Frequency Adjustment adjustment

⚠ The generator set must be running during these adjustments.

⚠ The engine speed (frequency) adjustment menus are not accessible on models with mechanical governors.

Tools: multimeter

Move the master switch to RUN; the engine starts and runtime hours display.
Hold the Select button about 5 seconds until the program version number displays.
Press the down arrow key then the up arrow key 3 times to enter adjustment mode.
1P: adjust voltage coarse in large increments (approximately 5-7 volts per step).
2P: adjust voltage fine in smaller increments (approximately 0.5-0.7 volts per step).
Adjust voltage stability (gain) coarse and fine.
3P: set volts/Hz (00=low, 09=high).
4P: adjust engine governor speed coarse and fine.
5P: adjust engine governor stability (gain) coarse and fine.
Enter SAVE mode and save settings before exiting the adjustment mode.

Voltage Adjustment Procedure adjustment

⚠ Hazardous voltage. Operate the generator set only when all guards and electrical enclosures are in place.

Tools: digital voltmeter, frequency meter

Connect a digital voltmeter from one side of the circuit breaker to the L0 terminal inside the controller assembly.
Start the generator set.
Enter the adjustment mode and increase or decrease voltage (parameter 1P) to the desired voltage.
Adjust the voltage gain (parameter 2P) until light flicker minimizes; save settings.
Check and readjust the voltage if necessary.
Set voltmeter to frequency; adjust engine governor speed (parameter 4P) to the cut-in frequency.
Set voltmeter to voltage; adjust volts/Hz (parameter 3P) until voltage begins to drop.
Set voltmeter to frequency; adjust engine governor speed (parameter 4P) to the operating frequency (50 or 60 Hz).
Readjust voltage gain (parameter 2P) until light flicker minimizes.
Check voltage; readjust voltage (parameter 1P) if necessary.
Save the settings.
Stop the generator set.

Governor System Operation Test Procedure diagnostic

⚠ Hazardous voltage. Operate the generator set only when all guards and electrical enclosures are in place.

Tools: voltmeter, feeler gauge

Verify carburetor throttle linkage is connected to the stepper motor.
Look for broken or loose wiring or plug connections if stepper motor moves erratically.
Check stepper motor operation at startup; note throttle positions.
If throttle moves fully open then steps to and stays fully closed, check the magnetic pickup.
Connect a voltmeter to the magnetic pickup leads; check for 1.75 volts AC minimum during cranking.
If below 1.75 VAC, verify magnetic pickup air gap is 0.5 mm (0.020 in.); adjust as needed.
After adjusting gap, recheck voltage; replace magnetic pickup if still below 1.75 VAC.
Disconnect magnetic pickup leads and open circuit breaker to test controller governing function.
Move throttle shaft/stepper motor fully counterclockwise (closed throttle).
Start the generator set; stepper motor should step clockwise to wide open throttle and remain there.
Place master switch in STOP; check stepper motor connections (leads 1A, 1B, 2A, 2B to P1-4, P1-5, P1-6, P1-7).
Check stepper motor coil resistance across pins 2 and 3 and across pins 1 and 4.

Network Bridge Diagnostics diagnostic

Check the network LEDs on the RJ45 connector for Ethernet network communication.
Check the STAT LED; if not lit, check connections and the engine starting battery.
Check the TX and RX LEDs for CAN data transmission and reception.
If neither the TX nor the RX LED flashes, check bridge power, connections, and settings.
If only one of the TX or RX LEDs flashes, check the connected devices on the generator set (CAN) side.

Resetting Controller after a Fault Shutdown diagnostic

⚠ Always identify and correct fault cause before resetting controller

Move master switch to OFF/RESET
Disconnect generator set from load using line circuit breaker or ATS
Identify and correct the cause of the fault shutdown
Start generator set by moving switch to RUN; test operate to verify shutdown cause corrected
Move master switch to OFF/RESET
Reconnect generator set to load using line circuit breaker or ATS
Move master switch to AUTO position for remote transfer switch or remote start/stop startup

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
		Remote start	Controller leads 3 and 4	Connect leads 3 and 4 from the ADC 2100 controller to the ATS engine start terminals or a remote start/stop switch.
	single phase	AC output leads to AC circuit breaker	L1/L2 (black)	Connect output leads going to the transfer switch to the AC circuit breaker load side; route through flexible conduit to circuit breaker box.
	single phase	Equipment ground	Green	Connect the green lead to the equipment ground terminal (labeled GRD).
	single phase	Neutral	L0 (white)	Connect the L0 white leads from the ATS and the main panel to the neutral terminal.
100 VAC	1	1Ph, 2W		Uu00; 60 Hz
100 VAC	1	1Ph, 3W		Uu00; 60 Hz
100/200 VAC	1	1Ph, 3W		Uu08; 60 Hz
110	Single (L0-L1)	Factory two-pole circuit breaker		50 Hz; not reconnectable
110	Single (L0-L2)	Factory two-pole circuit breaker		50 Hz; not reconnectable
110 VAC	1	1Ph, 2W		Uu05; 50 Hz
110 VAC	1	1Ph, 3W		Uu05; 50 Hz
110 volt	1	L0-L1		50 Hz; 3-wire configuration; 8.5/12RES not reconnectable
110 volt	1	L0-L2		50 Hz; 3-wire configuration; 8.5/12RES not reconnectable
110/190 VAC	3	Wye		Uu17; 50 Hz
110/220 VAC	1	1Ph, 3W		Uu07; 50 Hz
110/220 VAC	1	Dogleg		Uu07; 50 Hz
110/220 VAC	3	Delta		Uu15; 50 Hz
115 VAC	1	1Ph, 2W		Uu05; 50 Hz
115/200 VAC	3	Wye		Uu23; 50 Hz
115/230 VAC	1	1Ph, 3W		Uu02; 50 Hz
115/230 VAC	1	Dogleg		Uu06; 50 Hz
115/230 VAC	3	Delta		Uu14; 50 Hz
12		Engine starting battery	Positive (+) and negative (--)	12-volt engine electrical system, negative ground. Positive lead to starter solenoid; negative lead to ground terminal on or near starter motor.
120	Single (L0-L1)	Factory two-pole circuit breaker; 4 stator leads	1, 2, 3, 4 (output); 11, 44, 55, 66 (sensing/supply)	60 Hz, 110/220 and 120/240 V, 3-wire configuration; not reconnectable
120	Single (L0-L2)	Factory two-pole circuit breaker		60 Hz; not reconnectable
120 VAC		Utility Power terminals on field-connection terminal block		Utility power circuit must be backed up by the generator set
120 VAC	1	1Ph, 2W		Uu00; 60 Hz
120 VAC	1	1Ph, 3W		Uu00; 60 Hz
120 volt	1	L0-L1		60 Hz; 3-wire configuration; 8.5/12RES not reconnectable
120 volt	1	L0-L2		60 Hz; 3-wire configuration; 8.5/12RES not reconnectable

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

Common questions

What is the power rating of the Kohler 8.5RES?

The Kohler 8.5RES is rated 8 kW standby (8.5 kVA).

Which engine powers the Kohler 8.5RES?

The Kohler 8.5RES is powered by the Kohler CH20 engine.

What fuel type does the Kohler 8.5RES take?

The Kohler 8.5RES runs on natural gas or propane (LP) vapor.

What is the oil capacity of the Kohler 8.5RES?

The Kohler CH20 engine in the Kohler 8.5RES has an oil capacity of 1.9 liters.

What is the prime power rating of the Kohler 8.5RES?

The Kohler 8.5RES is rated 7 kW prime (7 kVA), against 8 kW standby.

How loud is the Kohler 8.5RES?

The Kohler 8.5RES is rated at 65.0 dBA at 23 ft m, per the manufacturer specification sheet.

How much does the Kohler 8.5RES weigh?

The Kohler 8.5RES has a dry weight of 182 kg (401 lb).

What voltage does the Kohler 8.5RES produce?

The Kohler 8.5RES is offered in 246/242 V, 1-phase.

What size battery does the Kohler 8.5RES need?

The Kohler 8.5RES uses 1 battery, 12 VDC V each, 525 minimum at -18 C (0 F) CCA, per the manufacturer specification sheet.

What alternator does the Kohler 8.5RES use?

The Kohler 8.5RES uses a 2F4 alternator. It has 2 poles. Insulation class Class 180 (H).

What oil filter fits the Kohler 8.5RES?

The Kohler 8.5RES uses oil filter part number 12 050 01.

Which air filter part number does the Kohler 8.5RES take?

The Kohler 8.5RES uses air filter part number ADV-6823-A.

Troubleshooting

Symptoms & remedies

Symptom	Cause	Remedy
Battery short circuits.		Disconnect the battery before generator set installation or maintenance. Remove all jewelry before servicing the equipment. Use tools with insulated handles. Remove the negative (--) lead first when disconnecting the battery. Reconnect the negative (--) lead last when reconnecting the battery. Never connect the negative (--) battery cable to the positive (+) connection terminal of the starter solenoid. Do not test the battery condition by shorting the terminals together.
Generator does not start	Low battery voltage or faulty starter motor	Check the battery and ensure it is fully charged. If necessary, replace the battery. Check the starter motor for proper operation.
Gas fuel leaks can cause an explosion.		Check the LPG vapor or natural gas fuel system for leakage by using a soap and water solution with the fuel system test pressurized to 6--8 ounces per square inch (10--14 inches water column). Do not use a soap solution containing either ammonia or chlorine because both prevent bubble formation. A successful test depends on the ability of the solution to bubble.
Fuse blows repeatedly		Replace Auxiliary winding fuse (F1). Contact an authorized distributor/dealer if the fuse blows again.
Generator set master switch in the OFF/RESET position		Move generator set master switch to the AUTO or RUN position.
Red LED stays on for more than 24 hours	One or more defective or damaged cells.	Load test the battery and replace, if necessary.

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing. Full Kohler 8.5RES troubleshooting guide (70 entries) →

Repair guides

Step-by-step procedures compiled from the Kohler service manual for this model.

Parts

Part #	Description	Qty	System
12 050 01	Oil Filter	1	Oil filter	Amazon eBay KuduParts $11.00 FridayParts $33.98
12 050 01-S	Filter, oil	1	Oil filter	Amazon eBay KuduParts $32.00 FridayParts $33.98
12 132 02	Spark plug	1	Spark plug	buy
12 132 02-S	Spark Plug	1	Spark plug	buy
24 050 01-S	Filter, breather	8	Filter	buy
24 083 02	Precleaner element	1	Air filter	buy
24 083 02-S	Precleaner	8	Air filter	buy
24 083 05-S	Precleaner	8	Air filter	buy
24 083 08	Air cleaner element	1	Air filter	buy
24 083 08-S	Element, air filter	1	Air filter	buy
24 083 09-S	Element, air filter	1	Air filter	buy
24 132 01	Spark Plug	2	Spark plug	buy
241927	Sensor, speed	1	Sensor	Amazon eBay $75.00
25 132 14-S	Spark plug	2	Spark plug	buy
269373	Alternator Assembly	1	Alternator	Amazon eBay
745-020-B0-003	Enclosure Grounding Stud		Grounding stud	Amazon
A-345052	Engine oxygen sensor	1	Sensor	Amazon eBay
ADV-6823-A	Air Filter, Spark Plug Location	1	Air filter	Amazon eBay
BKR-8YU11	Spark Plug, CH20/CH740	4	Spark plug	Amazon eBay
GM28823	Sensor, oil temperature	1	Sensor	Amazon eBay $50.00
GM28981	UEGO sensor interface harness		Sensor	eBay
GM29253-GA1	Controller Wiring Diagram	1	Controller wiring diagram	Amazon eBay
GM29385	UEGO oxygen sensor service kit		Sensor	eBay
X-6422-31	Seal		Seal	eBay
223316	Fuse, 10 A, 250 V	1	Service part / kit	Amazon eBay $31.37
292937	Fuse, 20 A, 250 V	1	Service part / kit	Amazon eBay $31.78 NAPA $17.36
345095	Annual Maintenance Kit	1	Service part / kit	Amazon eBay $67.47
358337	Fuse: Auxiliary Winding (F1) 10 Amp	1	Service part / kit	Amazon eBay $45.17 NAPA $65.06
A-345233	Lead	--	Service part / kit	Amazon eBay
AGS-10	AGS 10 inline fuse, battery charger (located in the battery lead)	1	Service part / kit	eBay
F-228605	Kit, voltage regulator	1	Service part / kit	Amazon eBay $539.95
GM10064	PCB assembly (relay controller)	1	Service part / kit	Amazon eBay $337.95
GM19462-KP4-QS	Carburetor heater kit	1	Service part / kit	Amazon eBay $115.00
GM24928	Circuit breaker		Service part / kit	eBay
GM29671	PCB Assy., Relay board 12V	1	Service part / kit	Amazon eBay $199.00
GM58703	Assy, J1939/ModBus/Ethernet Converter (network bridge)	1	Service part / kit	eBay
GM62345	Maintenance Service Kit	1	Service part / kit	eBay
GM62345-SKP1-QS	Maintenance Kit	1	Service part / kit	Amazon eBay
GM62346-SKP1-QS	Maintenance Kit	1	Service part / kit	Amazon eBay
GM62347-SKP1-QS	Maintenance Kit	1	Service part / kit	Amazon eBay $79.99
GM90365-SKP1-QS	Maintenance Kit	1	Service part / kit	Amazon eBay
GM90366-SKP1-QS	Maintenance Kit	1	Service part / kit	Amazon eBay

Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.

Fuel consumption

Rating	Load	L/h	gal/h
Standby	75%	3.2	0.85
Standby	100%	3.7	0.98

Available documents

Spec sheet — 12RES (Kohler)Spec sheet — 85-12-kw-Kohler-Residential-Generator (Kohler)Spec sheet — Spec Sheet Res (Kohler)Spec sheet — g4097 (Kohler)Operator's manual (Kohler)Operator's manual — 12 RES Operation (Kohler)Operator's manual — Operation Installation Res (Kohler)Operator's manual — tp6515 (Kohler)Reference (Kohler)Reference — g18146 (Kohler)Reference — tp6766cmp (Kohler)Reference — tp7004 (Kohler)Owner's manual — tp6331 (Kohler)Parts manual (Kohler)Parts manual — g6129 (Kohler)Parts manual — kohlerpow datasheet stepid-2757002 (Kohler)Service manual — 8.5 12 RES Service (Kohler)Service manual — g18118 (Kohler)Service manual — g260823 (Kohler)Service manual — tp6196 (Kohler)Service manual — tp6792 (Kohler)Service manual — tt1364 (Kohler)Service manual — tt1445 (Kohler)Service manual — tt1486 (Kohler)

This page was generated from the 24 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.

Kohler 8.5RES Generator Set

Service parts for the 8.5RES

Air intake

Oil system

Electrical

Ignition

Specifications

Engine

Same engine, other brands

Maintenance & consumables

Service intervals

Service specifications

Recommended fluids

Fault codes

Procedures

Voltage reconnection

Common questions

Troubleshooting

Symptoms & remedies

Repair guides

Parts

Fuel consumption

Available documents