Service parts for the 25REZG
Grouped by system, with how many of each the parts manual calls for.
Air intake
1 requiredFuel system
1 requiredBelts
1 requiredElectrical
1 requiredPrices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.
Specifications
| Fuel | Natural Gas / LP |
|---|---|
| Frequency | 60.0 Hz |
| Standby power | 25 kW |
| Standby kVA | 31 |
| Alternator | Fast-Response II (FRII) |
| Voltage options | 480 V |
| Max ambient | 50 °C |
| Sound level | 74.0 dBA @ 23 m |
Filters & service parts
model family| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | 253107 | 200 hr | Amazon eBay $69.00 NAPA $55.23 | ||
| Fuel filter | 343302 | 3652 hr | Amazon eBay | ||
| Oil filter | GM16703 | 150 hr | Amazon eBay $58.00 NAPA $3.59 | ||
| Battery | 1/12V, 650CCA, Wet | 256985 | Amazon eBay | ||
| Belt | GM16132 | Amazon eBay $86.00 | |||
| Spark plug | GM16531 | 3652 hr | Amazon eBay $8.08 NAPA $5.38 |
Compiled from this model's family documentation — may include parts for closely-related variants. Confirm the exact part for your serial number.
Service specifications
60| Type | Item | Value | Unit | Condition |
|---|---|---|---|---|
| Other | 10 in. weld flange bolt circle diameter B | 361.95 | mm (14.25 in.) | |
| Other | 10 in. weld flange outside diameter C | 406.4 | mm (16.0 in.) | |
| Other | 10 in. weld flange quantity of bolts / bolt hole diameter D | 12, 25.40 | mm (1.00 in.) | |
| Other | 12 in. weld flange bolt circle diameter B | 431.80 | mm (17.00 in.) | |
| Other | 12 in. weld flange outside diameter C | 482.6 | mm (19.0 in.) | |
| Other | 12 in. weld flange quantity of bolts / bolt hole diameter D | 12, 25.40 | mm (1.00 in.) | |
| Other | 14 in. weld flange bolt circle diameter B | 476.25 | mm (18.75 in.) | |
| Other | 14 in. weld flange outside diameter C | 533.4 | mm (21.0 in.) | |
| Other | 14 in. weld flange quantity of bolts / bolt hole diameter D | 12, 28.58 | mm (1.13 in.) | |
| Other | 16 in. weld flange bolt circle diameter B | 539.75 | mm (21.25 in.) | |
| Other | 16 in. weld flange outside diameter C | 596.9 | mm (23.5 in.) | |
| Other | 16 in. weld flange quantity of bolts / bolt hole diameter D | 16, 28.58 | mm (1.13 in.) | |
| Other | 18 in. weld flange bolt circle diameter B | 577.85 | mm (22.75 in.) | |
| Other | 18 in. weld flange outside diameter C | 635.0 | mm (25.0 in.) | |
| Other | 18 in. weld flange quantity of bolts / bolt hole diameter D | 16, 31.75 | mm (1.25 in.) | |
| Other | 20 in. weld flange bolt circle diameter B | 635.00 | mm (25.00 in.) | |
| Other | 20 in. weld flange outside diameter C | 698.5 | mm (27.5 in.) | |
| Other | 20 in. weld flange quantity of bolts / bolt hole diameter D | 20, 31.75 | mm (1.25 in.) | |
| Other | 5 in. weld flange bolt circle diameter B | 215.90 | mm (8.50 in.) | |
| Other | 5 in. weld flange outside diameter C | 241.30 | mm (9.50 in.) | |
| Other | 5 in. weld flange quantity of bolts / bolt hole diameter D | 8, 22.23 | mm (0.88 in.) | |
| Other | 6 in. weld flange bolt circle diameter B | 254.0 | mm (10.0 in.) | |
| Other | 6 in. weld flange outside diameter C | 279.4 | mm (11.0 in.) | |
| Other | 6 in. weld flange quantity of bolts / bolt hole diameter D | 8, 22.23 | mm (0.88 in.) | |
| Other | 8 in. weld flange bolt circle diameter B | 298.45 | mm (11.75 in.) | |
| Other | 8 in. weld flange outside diameter C | 342.9 | mm (13.5 in.) | |
| Other | 8 in. weld flange quantity of bolts / bolt hole diameter D | 8, 22.23 | mm (0.88 in.) | |
| Other | Weld flange angle A (10, 12, 14 in. nominal pipe size) | 30 | deg. | |
| Other | Weld flange angle A (16, 18, 20 in. nominal pipe size) | 22.5 | deg. | |
| Other | Weld flange angle A (5, 6, 8 in. nominal pipe size) | 45 | deg. | |
| Torque | 1-12 fastener | 283.0 (209) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 1-8 fastener | 259.0 (191) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 1/2-13 fastener | 60.0 (44) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 1/2-20 fastener | 66.0 (49) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 1/4-20 fastener | 6.8 (60) | Nm (in. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 1/4-28 fastener | 8.1 (72) | Nm (in. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 10-24 fastener | 2.9 (26) | Nm (in. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 10-32 fastener | 2.9 (26) | Nm (in. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 3/4-10 fastener | 199.0 (147) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 3/4-16 fastener | 222.0 (164) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 3/8-16 fastener | 24.0 (18) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 3/8-24 fastener | 27.0 (20) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 5/16-18 fastener | 13.6 (120) | Nm (in. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 5/16-24 fastener | 14.9 (132) | Nm (in. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 5/8-11 fastener | 113.0 (83) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 5/8-18 fastener | 128.0 (94) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 7/16-14 fastener | 39.0 (29) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 7/16-20 fastener | 43.0 (32) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 8-32 fastener | 1.8 (16) | Nm (in. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 9/16-12 fastener | 81.0 (60) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | 9/16-18 fastener | 91.0 (67) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 2 or 5 |
| Torque | M10 x 1.25 fastener | 31.0 (23) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 5.8 or 8.8 |
| Torque | M10 x 1.50 fastener | 30.0 (22) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 5.8 or 8.8 |
| Torque | M12 x 1.50 fastener | 56.0 (41) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 5.8 or 8.8 |
| Torque | M12 x 1.75 fastener | 53.0 (39) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 5.8 or 8.8 |
| Torque | M14 x 1.50 fastener | 87.0 (64) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 5.8 or 8.8 |
| Torque | M14 x 2.00 fastener | 83.0 (61) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 5.8 or 8.8 |
| Torque | M16 x 1.50 fastener | 132.0 (97) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 5.8 or 8.8 |
| Torque | M16 x 2.00 fastener | 127.0 (94) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 5.8 or 8.8 |
| Torque | M18 x 1.50 fastener | 189.0 (140) | Nm (ft. lb.) | Assembled into cast iron or steel, Grade 5.8 or 8.8 |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Procedures
2Common Hardware Application installation
- Determine entry hole type: round or slotted.
- Determine exit hole type: fixed female thread (weld nut), round, or slotted.
- For round and slotted exit holes, determine if hardware is greater than 1/2 inch in diameter.
- Hardware greater than 1/2 inch in diameter uses a standard nut and SAE washer.
- Hardware 1/2 inch or less in diameter can use a properly torqued whiz nut or spiralock nut.
- Always use a washer between hardware and a slot.
- Always use a washer under a nut.
- Use a washer under a bolt when the female thread is fixed (weld nut).
How to Find Part Numbers operation
- Locate the generator set nameplate to identify the generator set spec number.
- Locate the second nameplate listing accessories to identify installed modules; on some models it is inside the junction box.
- Turn to the Specification Number Index; the first column lists generator set spec numbers.
- Identify the group most likely to include the service part number.
- Find the group variation number at the intersection of the spec number row and group column.
- Page forward to locate that group or find the page in the Table of Contents.
- Find the part on the illustration and note the item number, or find the part description in the parts list.
- Select the part number that corresponds to your group variation using the column on the right side of the parts list table.
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 |
|---|---|---|---|---|
| 12-Lead | Alternator Reconnections diagram ADV-5875B-M (page 16) | |||
| 4-Lead | Alternator Reconnections diagram ADV-5875A-M (page 15) |
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
How many kW is the Kohler 25REZG?
The Kohler 25REZG is rated 25 kW standby (31.0 kVA).
What fuel does the Kohler 25REZG use?
The Kohler 25REZG runs on Natural Gas / LP.
How loud is the Kohler 25REZG?
The Kohler 25REZG is rated at 74.0 dBA at 23 m, per the manufacturer specification sheet.
What voltages is the Kohler 25REZG available in?
The Kohler 25REZG is offered in 480 V.
What alternator does the Kohler 25REZG use?
The Kohler 25REZG uses a Fast-Response II (FRII) alternator.
What oil filter fits the Kohler 25REZG?
The Kohler 25REZG uses oil filter part number GM16703.
What fuel filter does the Kohler 25REZG use?
The Kohler 25REZG uses fuel filter part number 343302.
What air filter fits the Kohler 25REZG?
The Kohler 25REZG uses air filter part number 253107.
Parts
1| Part # | Description | Qty | System | |
|---|---|---|---|---|
| GM39458 | Coolant Temperature Sender (Decision-Maker 3+) | 1 | Sensor | 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.
Available documents
Reference (Kohler)Reference — G6-39 0918AZ (Kohler)Parts manual — tp6667 (Kohler)Service manual — tp6712 (Kohler)Service manual — tp6799 (Kohler)
This page was generated from the 5 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.