Service parts for the 8.5RMY
Grouped by system, with how many of each the parts manual calls for.
Air intake
1 requiredIgnition
1 requiredPrices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.
Specifications
| Oil capacity | 1.9 L |
|---|
Engine
| Oil capacity | 1.9 L |
|---|---|
| Coolant capacity | 0.0 L |
| Displacement | 8.5 L |
| Aspiration | air-cooled |
| Rated speed | 3600 rpm |
Maintenance & consumables
for the Kohler CH20| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | Element, air filter | 24 083 08-S | buy | ||
| Fuel filter | — | ||||
| Oil filter | Oil filter | 12 050 01 | 200 hr | Amazon $30.38 eBay KuduParts $11.00 | |
| Battery | Replace with identical type and rating | — | |||
| Belt | — | ||||
| Coolant | — | ||||
| 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 specifications
1| Type | Item | Value | Unit | Condition |
|---|---|---|---|---|
| Voltage | Oxygen sensor output voltage for correct fuel mixture adjustment | 0.5 | vdc (target, adjust within -0.3) | 90-100% rated load, normal operating temperature |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Procedures
1Fuel Metering Valve Adjustment Procedure adjustment
⚠ Disconnect battery cables before working on generator set (negative lead first, reconnect last)
⚠ Hot engine and exhaust system can cause severe injury or death; allow to cool before servicing
Tools: digital volt meter (DVM), oxygen sensor (A-345052), load bank capable of rated kW for the fuel being used
- Place generator set master switch OFF
- Disconnect power to battery charger, if equipped
- Disconnect engine starting battery, negative lead first
- Remove oxygen sensor plug from exhaust manifold
- Install oxygen sensor in exhaust manifold where plug was removed
- Check master switch is OFF, reconnect battery negative lead last
- Place controller master switch to RUN to start generator set
- Allow generator set to run until normal operating temperature
- Apply 90-100% of rated load
- Connect DVM leads between oxygen sensor lead and ground, measure output voltage
- Adjust fuel metering valve to obtain 0.5 vdc -0.3 output from oxygen sensor
- Remove load, allow generator set to run unloaded 5-10 minutes to cool
- Place master switch OFF, disconnect battery negative lead first
- Disconnect DVM leads, allow exhaust system to cool, remove oxygen sensor
- Apply antiseize compound to exhaust plug, reinstall plug, reconnect battery negative last
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 engine is in the Cummins/Onan 8.5RMY?
The Cummins/Onan 8.5RMY is powered by the Kohler CH20 engine.
What is the oil capacity of the Cummins/Onan 8.5RMY?
The Kohler CH20 engine in the Cummins/Onan 8.5RMY has an oil capacity of 1.9 liters.
Which oil filter part number does the Cummins/Onan 8.5RMY take?
The Cummins/Onan 8.5RMY uses oil filter part number 12 050 01.
What air filter does the Cummins/Onan 8.5RMY use?
The Cummins/Onan 8.5RMY uses air filter part number 24 083 08-S.
Parts
42| Part # | Description | Qty | System | |
|---|---|---|---|---|
| 12 050 01 | Oil filter | 1 | Oil filter | Amazon $30.38 eBay KuduParts $11.00 |
| 12 050 01-S | Filter, oil | 40 | Filter | Amazon $30.38 eBay KuduParts $32.00 |
| 12 132 02 | Spark plug | 1 | Spark plug | buy |
| 12 132 02-S | Spark plug | 2 | Spark plug | buy |
| 24 050 01-S | Filter, breather | 8 | Filter | buy |
| 24 083 02 | Precleaner element | 1 | 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 |
| 25 132 14-S | Spark plug (RFI) | 2 | Spark plug | buy |
| 269373 | Alternator Assembly | 5 | 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 $171.06 eBay $31.37 |
| 24 083 02-S | Pre-cleaner | 8 | Service part / kit | buy |
| 24 083 05-S | Pre-cleaner | 8 | Service part / kit | buy |
| 292937 | Fuse, 20 A, 250 V | 1 | Service part / kit | Amazon eBay $31.78 |
| 345095 | Annual Maintenance Kit | 1 | Service part / kit | Amazon eBay $67.47 |
| 358337 | Fuse: Auxiliary Winding (F1) 10 Amp | 1 | Service part / kit | Amazon $101.99 eBay $45.17 |
| 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 |
| 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.