Description

Kohler CH18, CH20, CH22, CH23, CH25 Service Manual

I’ve seen more than a few weekend warriors turn a simple valve adjustment into a seized engine because they trusted a generic aftermarket manual. Wrong torque values on the head bolts, skipped lube procedures — that stuff costs you time and parts. This is the factory-issued Kohler CH18, CH20, CH22, CH23, CH25 Service Manual — 218 pages of the same documentation Kohler techs use. No guesswork, no copy-paste errors. If you’re rebuilding or diagnosing any of these Command series engines, you want this on your bench, not some third-party PDF that rounds off numbers.

12 Sections from Safety to Clutch

This manual covers the full sweep of the engine life. It opens with Section 1 (Safety and General Information) — and I don’t skip that page. Rotating parts, hot components, accidental starts: Kohler prints the warnings because people die ignoring them. Then Section 2 lists every Special Tools you need before you crack a bolt. Sections 4 through 8 go deep into Air Cleaner and Air Intake System, Fuel System and Governor (including LPG and EFI variants), Lubrication System, Retractable Starter, and Electrical System and Components. Section 9 through 11 walk you through Disassembly, Inspection and Reconditioning, and Reassembly. Section 12 covers the clutch. That’s the kind of structure that keeps you from putting a piston in backwards at 2 AM.

Fuel System and Governor: Factory Diagnostics

Section 5 is where most DIY guys get lost. The fuel system on these Command engines isn’t simple — mechanical governor, optional LPG, or Electronic Fuel Injection. The manual gives you the exact fuel pressure specs and governor adjustment procedures from the factory. No running rich for weeks because you guessed at the main jet setting. Page references for charge pressure? It’s in there. Pull the Fuel System and Governor section and follow the step-by-step — not a sequence you can infer from a parts diagram.

Electrical System and Components: Don’t Guess the Wiring

Section 8 covers the Electrical System and Components — charging coils, rectifier-regulator, ignition module, starter solenoid. I’ve chased electrical ghosts on these engines because someone swapped a generic regulator and didn’t match the output curve. The manual includes OEM wiring diagrams and pin-out voltage tests. Want to know if your stator is putting out 20 volts AC at 3600 RPM? It’s on the page. If you’re hooking up a battery or a remote start panel, you need the factory ground path, not a sketch from a forum.

Get the Right Special Tools First

Section 2 lists the special tools Kohler designed for these blocks. Some of them you can fabricate — like the flywheel holder — but the crankcase alignment tool and the valve spring compressor part numbers are there. I’ve seen techs ruin a crankshaft seal because they improvised a puller. Spend the time to read that list before you start. You can source the tools from Kohler or find equivalent OEM-grade substitutes. The manual doesn’t assume you own every tool, but it tells you exactly what you need to avoid damaging parts.

Does This Manual Cover the CH18 to CH25?

Yes — the CH18, CH20, CH22, CH23, and CH25 horizontal crankshaft versions are all in this single manual. Same architecture, different displacements. Torque specs for the cylinder head, connecting rod, and flywheel vary between models, and the manual lists each separately. If you’re working on a CH23 and you use CH20 rod bolt torque, you’ll stretch the fastener. Don’t do that. The table of contents flags the differences per engine. Use the correct data for your specific model.

Torque Specs and Fluid Capacities

Kohler prints torque values in foot-pounds and inch-pounds — Imperial units, as it should be for North American technicians. Oil capacity, cooling fan clearance, valve lash settings: all from the same OEM source. The manual also includes the break-in procedure and the correct oil viscosity for different ambient temperatures. That’s the kind of detail you don’t get from a $10 eBay scan. A single stripped head bolt on a rebuild will cost you more than this manual.

One more thing: the Retractable Starter section (Section 7) has a specific warning about the recoil spring. Uncoiling spring can cause severe injury — they recommend safety goggles and face protection. I’ve seen those springs let go. Heed the warning.

If you’re also working on other small engines, check the related manuals: Kohler XT-6 XT-7 Service Manual – 84 Pages OEM Factory Specs covers the smaller single-cylinder line. Kohler OHC 16 HP, OHC 18 HP Service Manual – OEM Factory Specs handles the overhead cam variants. And for the older Command 5-6 HP models, Kohler Command Service Manual – OEM Factory Specs for 5-6 HP Engines has the data you need.

Outside the Kohler world, the same principle applies — whether it’s a Manual Transmission or any other mechanical system, factory documentation beats aftermarket every time. I’ve used these manuals to train green techs on the difference between a gearbox and an engine. Don’t rely on forum wisdom for a job that can seize a motor. Get the Manual Transmission you need — in this case, the exact factory data for your Kohler Command.

Does this manual include the EFI fuel system?

Yes. Section 5B covers the Electronic Fuel Injection system separately from the carbureted and LPG versions. Includes fuel pressure specifications, injector testing, and ECU troubleshooting.

How many pages?

218 pages.

Stop chasing aftermarket misinformation. Access the Factory Manual and get the OEM torque values, wiring diagrams, and step-by-step rebuild procedures that keep your Kohler Command engine running on spec.