Specifications
| Standby power | 18 kW |
|---|
Filters & service parts
model family| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | — | 400 hr | |||
| Fuel filter | — | 400 hr | |||
| Oil filter | — | 50 hr | |||
| Battery | check electrolyte level | — | |||
| Belt | New 36--46 kg (79--101 lb); used 25--34 kg (56--75 lb) | — | |||
| Coolant | 19.0 | — | |||
| Oil | — | 50 hr | |||
| Spark plug | — |
Compiled from this model's family documentation — may include parts for closely-related variants. Confirm the exact part for your serial number.
Service intervals
35| Item | Action | Hours | Months | Notes |
|---|---|---|---|---|
| Engine oil | Change | 50 hr | 12 mo | 50 or Y |
| Oil filter(s) | Replace | 50 hr | 12 mo | 50 or Y; service more frequently in dusty areas |
| Blow dust out of generator | Clean | 300 hr | 2 Y or 300; more often in dusty conditions | |
| Air cleaner element | Replace | 400 hr | 6 mo | S |
| Bolt torque | Adjust | 500 hr | 3 Y or 500 | |
| Valve clearance | Adjust | 500 hr | 3 Y or 500 | |
| Wire-cable insulation breakdown | Test | 500 hr | 3 Y or 500 | |
| Brushes | Replace | 1000 hr | replace as necessary | |
| Battery charger operation, charge rate | Check | 1 mo | M | |
| Battery electrolyte level | Check | 1 mo | M | |
| Battery specific gravity, charge state | Test | 1 mo | M | |
| Bearing condition | Inspect | 12 mo | Y; replace as necessary | |
| Choke, carburetor adjustment | Adjust | 6 mo | S | |
| Circuit breakers, fuses | Test | 1 mo | M | |
| Clean and tighten battery terminals | Clean | 3 mo | Q | |
| Coolant | Change | 12 mo | Y | |
| Crankcase breather | Clean | 3 mo | Q; 10/12 kW also 100 h | |
| Exciter | Test | 12 mo | Y | |
| Fuel filter(s) | Change | 3 mo | Q | |
| Fuel piping | Inspect | 12 mo | Y | |
| Gasoline supply | Replace | 6 mo | S | |
| Governor operation, lubricate moving parts | Lubricate | 1 mo | M | |
| Ignition components | Inspect | 12 mo | Y | |
| Measure and record winding resistance with Megger | Test | 12 mo | Y | |
| Radiator exterior | Clean | 12 mo | Y | |
| Recharge after engine start | Check | 1 mo | M | |
| Remove corrosion, clean and dry battery and rack | Clean | 1 mo | M | |
| Run generator set | Test | 1 mo | M | |
| Safety and alarm operation | Test | 6 mo | S | |
| Tighten DC electrical connections | Adjust | 6 mo | S | |
| Tighten control and power wiring connections | Adjust | 12 mo | Y | |
| Transfer switch main contacts | Inspect | 12 mo | Y | |
| Voltage regulator | Test | 12 mo | Y | |
| Voltage-sensing device/relay adjustment | Adjust | 12 mo | Y | |
| Wire abrasions where subject to motion | Inspect | 3 mo | Q |
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
59| Type | Item | Value | Unit | Condition |
|---|---|---|---|---|
| Gap | Kohler governor magnetic pickup air gap | 1.02 ±0.127 | mm | 0.040 ±0.005 in. |
| Gap | Magnetic pickup air gap | 0.51--1.27 | mm | 0.020--0.050 in. |
| Gap | Magnetic pickup air gap, A-249922 | 0.37 ±0.127 | mm | 0.015 ±0.005 in. |
| Other | Battery cold cranking amps, above -1.1 C | 235 minimum | CCA | above -1.1 C (30 F) |
| Other | Battery cold cranking amps, below -1.1 C | 400 minimum | CCA | below -1.1 C (30 F) |
| Other | Battery specific gravity, fully charged | 1.260 | at 26.7 C (80 F) | |
| Other | Battery specific gravity, recharge threshold | 1.215 | at 26.7 C (80 F) | |
| Other | Belt tension, new belt | 36--46 | kg | 79--101 lb. |
| Other | Belt tension, used belt | 25--34 | kg | 56--75 lb.; used after 10 min operation |
| Pressure | Anticipatory low oil pressure switch | 138 ±14 | kPa | prealarm |
| Pressure | Low oil pressure fault, 5-light controller | 49 | kPa | 7.1 psi |
| Pressure | Low oil pressure shutdown switch | 103 ±14 | kPa | |
| Pressure | Operating oil pressure | 276--414 | kPa | 18 kW; 40--60 psi |
| Pressure | Operating oil pressure | approximately 150 | kPa | 10/12 kW; 21.7 psi |
| Resistance | Exciter armature resistance | 0.6--0.8 | ohm | continuity |
| Resistance | Exciter field resistance | 4.5 ±10% | ohm | cold |
| Resistance | Exciter field resistance | 5.0 ±5% | ohm | cold |
| Resistance | Main field (rotor) resistance | 6.0--7.4 | ohm | cold |
| Resistance | Main field (rotor) resistance | 7.0--8.6 | ohm | cold |
| Resistance | Oil pressure sender at 0 kPa (0 psi) | 240 ±10% | ohm | 0 kPa (0 psi) |
| Resistance | Oil pressure sender at 345 kPa (50 psi) | 103 ±10% | ohm | 345 kPa (50 psi) |
| Resistance | Oil pressure sender at 690 kPa (100 psi) | 33 ±10% | ohm | 690 kPa (100 psi) |
| Resistance | Rotor resistance | 2.8±10% | ohm | cold |
| Resistance | Rotor resistance | 3.9±10% | ohm | cold |
| Resistance | Stator winding 1--2, 3--4 | 0.05 | ohm | cold; ±10% |
| Resistance | Stator winding 1--2, 3--4 | 0.06 | ohm | cold; ±10% |
| Resistance | Stator winding 1--4, 2--5, 3--6, etc. | 0.04 | ohm | cold; ±10% |
| Resistance | Stator winding 1--4, 2--5, 3--6, etc. | 0.19 | ohm | cold; ±10% |
| Resistance | Stator winding 33--44 | 0.05 | ohm | cold; ±10% |
| Resistance | Stator winding 33--44 | 0.06 | ohm | cold; ±10% |
| Resistance | Stator winding 55--33 | 1.10 | ohm | cold; ±10% |
| Resistance | Stator winding 55--33 | 1.26 | ohm | cold; ±10% |
| Resistance | Stator winding 55--66 | 1.30 | ohm | cold; ±10% |
| Resistance | Stator winding 55--66 | 1.40 | ohm | cold; ±10% |
| Resistance | Water temperature sender at 104 C (220 F) | 47 | ohm | 104 C (220 F) |
| Resistance | Water temperature sender at 38 C (100 F) | 450 | ohm | 38 C (100 F) |
| Resistance | Water temperature sender at 71 C (160 F) | 130 | ohm | 71 C (160 F) |
| Speed | Governor speed | 1500 | rpm | 50 Hz |
| Speed | Governor speed | 1800 | rpm | 60 Hz |
| Speed | Relay controller overspeed shutdown | 62 | Hz | 50 Hz models; 1860 rpm |
| Speed | Relay controller overspeed shutdown | 72 | Hz | 60 Hz models; 2160 rpm |
| Temperature | Anticipatory high engine temperature switch | 121±4 | °C | prealarm |
| Temperature | Coolant freezing protection, 50% ethylene glycol | -37 | °C | -34 F |
| Temperature | Coolant overheating protection, 50% ethylene glycol | 129 | °C | 265 F |
| Temperature | High engine temperature shutdown switch | 103±4 | °C | |
| Temperature | Thermostat opening temperature | 91 | °C | 195 F; wet exhaust manifold |
| Temperature | Thermostat test temperature | 93 | °C | 199 F |
| Temperature | Thermostat wide open temperature | 104 | °C | 219 F |
| Torque | Drive disc to flywheel | 19 | Nm | 10/12RY/RFY; 168 in. lb. |
| Torque | Drive disc/rotor nuts | 7.9 | Nm | 10/12RY/RFY; 70 in. lb. |
| Torque | Drive discs and rotor to flywheel | 65 | Nm | 18RY/RFY/RZ/RFZ; 50 ft. lb. |
| Torque | Intake manifold bolts | 16--20 | Nm | 10/12 kW; 12--15 ft. lb. |
| Torque | Overbolt torque | 24.4 | Nm | 18RY/RFY/RZ/RFZ; 216 in. lb. |
| Torque | Overbolt torque | 6.8 | Nm | 10/12RY/RFY; 60 in. lb. |
| Voltage | Kohler governor magnetic pickup voltage during cranking | 1.75 minimum | V AC | during engine cranking |
| Voltage | Magnetic pickup signal voltage | approximately 7 | V DC | engine running |
| Voltage | Magnetic pickup supply voltage | approximately 9.5 | V DC | master switch OFF/OFF-RESET |
| Voltage | PowerBoost III/IIIE voltage adjustment range | 100--130 | V | |
| Voltage | PowerBoost V voltage adjustment range | 190--270 | V | line-to-line |
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 |
|---|---|---|---|---|---|
| Coolant | 50% ethylene glycol and 50% clean, softened water | permanent-type coolant | above -37°C | 11.8 L | Freezing protection to -37 C (-34 F), overheating protection to 129 C (265 F); 10/12 kW capacity. |
| Fuel | LP gas or natural gas | LP liquid withdrawal system available as accessory. | |||
| Fuel | regular grade unleaded gasoline with pump sticker octane rating 87 or higher | gasohol max 10% ethanol; methanol max 5% with cosolvents and corrosion inhibitors |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Procedures
12Drive Belt Tension Adjustment adjustment
Tools: belt tension gauge
- Check belt tension with belt tension gauge.
- Loosen alternator and/or governor mounting and adjusting bolts.
- Move component away from engine until correct tension.
- Retighten mounting bolts.
Electronic Governor Adjustment adjustment
Tools: frequency meter or tachometer
- Verify actuator swivel fully threaded and secured.
- Back out idle adjust screw.
- Snap linkage back to idle and listen for click.
- Turn threaded rod 1/2 turn at a time until sharp click.
- Set actuator rod about 90 degrees to throttle lever at no load rated rpm.
- Tighten ball joint locknuts.
- Select 50 Hz or 60 Hz with jumper; do not jumper for 60 Hz.
- Adjust gain at full load until stable at all loads.
Gasoline Carburetor Adjustment adjustment
⚠ Do not force idle speed mixture screw.
- With engine stopped, turn idle mixture screw in until lightly seated.
- Turn idle mixture screw out 1-3/4 turns.
- Start engine and run at no load about 5 minutes.
- Adjust idle mixture screw ±3/8 turn for best stability.
- Stop generator set.
- Adjust governed speed via electronic governor if incorrect.
Gasoline Choke Adjustment adjustment
- Loosen screws securing choke bracket.
- Shift choke assembly position.
- Set choke plate within 10 degrees of full-closed at about 21 C (70 F).
LP/Natural Gas Conversion adjustment
- Remove retaining screw from underside of gas regulator.
- Remove retainer and internal spring for LP gas operation.
- Reinstall retaining screw.
- Save spring and retainer for conversion back to natural gas.
- For natural gas, replace spring and retainer.
- Rotate spring retainer to obtain 5 in. water column at full load.
12-Lead Separate Excitation diagnostic
⚠ Observe hazardous voltage precautions.
Tools: DC ammeter, 10-amp fuse, 12-volt automotive battery
- Disconnect all leads from voltage regulator.
- Remove exciter field F1 and F2 leads from terminal strip.
- Connect ammeter and 10-amp fuse in series with F1 to 12-volt battery.
- Record ammeter reading; expected battery voltage divided by exciter resistance.
- Start engine and check ammeter remains stable.
- Check AC output across stator leads against specification.
- If rotor and stator test good, replace voltage regulator.
4-Lead Separate Excitation diagnostic
⚠ Observe hazardous voltage precautions.
Tools: DC ammeter, 10-amp fuse, 12-volt automotive battery
- Disconnect all leads from voltage regulator.
- Connect DC ammeter, 10-amp fuse, and 12-volt battery to brush leads.
- Record ammeter reading; expected battery voltage divided by rotor resistance.
- Start engine and check ammeter remains stable.
- Check AC output across stator leads against specification.
- If rotor and stator test good, replace voltage regulator.
PowerBoost III/IIIE Voltage Regulator Test diagnostic
⚠ Do not touch voltage regulator heat sink when testing.
Tools: Variable transformer 0--140 V, AC voltmeter, 120-volt 100-watt lamp
- Connect variable transformer, AC voltmeter, regulator, and 120-volt lamp.
- Set variac to zero and plug in.
- Increase to 100 volts; lamp should light.
- Increase to 120 volts; lamp should go out.
- If lamp behavior fails, replace voltage regulator.
Battery Cleaning maintenance
⚠ Do not let cleaning solution enter battery cells.
Tools: wire brush
- Disconnect cables; remove negative lead first.
- Remove corrosion with wire brush from posts and connectors.
- Clean battery and cables with baking soda and water solution.
- Flush with clean water and wipe dry.
- Reconnect cables and coat terminals with petroleum jelly.
Battery Electrolyte Level Check maintenance
⚠ Do not add fresh electrolyte.
- Remove filler caps.
- Check electrolyte level is up to bottoms of filler holes.
- Refill with distilled or clean tap water as necessary.
- Tighten filler caps.
Battery Specific Gravity Check maintenance
Tools: battery hydrometer
- Draw electrolyte from each cell into hydrometer.
- Read number at top of electrolyte level.
- Fully charged is 1.260 at 26.7 C (80 F).
- Charge battery if below 1.215 at 26.7 C (80 F).
- Correct reading for electrolyte temperature if needed.
Cooling System Drain and Refill maintenance
⚠ Allow engine to cool before removing pressure cap.
- Remove radiator cap and open radiator petcock and engine block drain.
- Drain coolant.
- Close drain plug and petcock.
- Fill radiator with recommended coolant mixture.
- Run engine until thermostat opens and upper hose is hot.
- Stop engine, allow cooling, and add coolant to 19--38 mm below filler neck.
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 |
|---|---|---|---|---|
| 100-120 | 1 | 4-lead, 2 wire | L1; L0 | Single-pole circuit breaker; CT2 not used |
| 100-120 | 1 | 4-lead, 3 wire | L0-L1; L0-L2 | 60/50 Hz; jumper lead used; factory two-pole or two 1-pole circuit breakers |
| 100-120/200-240 | 1 | 4-lead, 3 wire | L0-L1; L0-L2; L1-L2 | 60/50 Hz; jumper lead not used |
| 120/240 (60 Hz); 110/220 (50 Hz) | 1 | 12-lead, 3 wire | Used on generators 20-100 kW only | |
| 120/240 (60 Hz); 110/220 (50 Hz) | 3 | 12-lead, 4 wire delta | ||
| 120/240 or 120/208 (60 Hz); 120/208 or 110/190 (50 Hz) | 3 | 12-lead, 4 wire low wye | ||
| 200-240 | 1 | 4-lead, 2 wire | L1; L0 | Single-pole circuit breaker; CT2 not used |
| 277/480 (60 Hz); 220/380 (50 Hz) | 3 | 12-lead, 3 wire high wye | ||
| 600 | 3 | 6-lead stator | 600 volt |
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 size generator is the Kohler 18RZ?
The Kohler 18RZ is rated 18 kW standby.
Repair guides
7- 12-Lead Separate Excitation
- 4-Lead Separate Excitation
- Battery Electrolyte Level Check
- Cooling System Drain and Refill
- Gasoline Carburetor Adjustment
- LP/Natural Gas Conversion
- PowerBoost III/IIIE Voltage Regulator Test
Step-by-step procedures compiled from the Kohler service manual for this model.
Parts
1model family| Part # | Description | Qty | System | |
|---|---|---|---|---|
| 226881 | Radiator outlet tube kit | 1 | Hose | eBay |
Compiled from this model's family documentation — may include parts for closely-related variants. Confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.
Available documents
Owner's manual — tp5870 (Kohler)Parts manual — tp5543 (Kohler)Service manual — 16953202-18RY (Kohler)
This page was generated from the 3 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.