Onan 16, 18, 20 & 24 HP Gasoline Engine Service Manual by John Deere (P/N CTM2)

John Deere's CTM2 Component Technical Manual covers repair of Onan B43E, B43G, B48G, P218G, P220G, and T260 engines. Procedures focus on engine components serviced on a workbench or engine stand.

• Air cleaner and cylinder heads: Air cleaner and breather service, intake manifold removal and installation, cylinder head inspection, and model-specific head assembly.

• Valve train and timing: Valve, guide, seat, and tappet inspection; valve clearance adjustment; flywheel service; camshaft overhaul and timing gear alignment.

• Pistons and bottom end: Piston and connecting rod inspection, cylinder bore deglazing, crankshaft and main bearing replacement, and end play checks.

• Lubrication and governor: Oil pump overhaul, oil pressure regulating valve service, oil base and filter adapter work, and governor assembly and linkage repair.

• Carburetor service: Disassembly, passage cleaning, float and needle valve inspection, throttle and choke shaft work, and float level and drop adjustments.

• Starter and ignition: Bendix and solenoid drive starter overhaul, exploded component views, electrical bench tests, and stator, rectifier-regulator, and ignition component replacement.

This manual was written for experienced service technicians working with engine repair tools and precision measuring equipment.

Engine Applications and Service Limits

For John Deere lawn and garden tractors, the Engine Application Chart pairs the 316 with B43E/P218G, the 318 with B43G/P218G, and the 420 with B48G/P220G. Front mower applications are F910 with B48G/P220G and F930 with T260.

Match the engine designation on the serial-number plate beneath the air cleaner to the relevant procedures. The machine technical manual is also required for engine removal and installation, operating theory, machine-level diagnosis, and starting circuit diagnosis.

Internal Engine Inspection and Reassembly

A cylinder bore cutaway accompanies the flex-hone deglazing procedure. PLASTIGAGE bearing-clearance measurements and dimensional wear tables help assess whether connecting rods, pistons, and crankshaft components need replacement or machining by a qualified shop.

Valve work includes seat reconditioning with the JDG 507 valve seat cutter and model-specific valve guide tooling. Cylinder head torque-sequence illustrations and camshaft timing-mark views support reassembly; reference tables cover valve clearances and English and metric fastener torques.

Reassembly cautions: The manual warns that swapped or reversed connecting rod caps can damage the rods and crankshaft. Drawing a misaligned bearing plate inward with its screws can damage the lock pins, thrust washer, or crankshaft.

Carburetor, Lubrication and Governor Details

Carburetor illustrations distinguish T260 float retention from the other engine arrangements and document float level and drop checks. Choke linkage adjustment is covered with the engine installed; final engine-speed adjustment requires the machine technical manual.

Oil pump gear backlash tables distinguish P218G/P220G specifications from the other covered engines. Separate procedures address oil line adapters, filter bypass hardware, and governor cup and linkage inspection.

Starter Tests and Ignition Variants

Solenoid starter bench-test connection diagrams pair wiring layouts with symptom-based checks. Armature tests cover grounds, open circuits, and shorts using an ohmmeter or growler; overrunning-clutch inspection is covered separately. The solenoid drive starter section specifies complete starter replacement for a defective armature.

Starter bracket distinction: The adjustable-bracket procedure applies to John Deere 318 machines through S/N 231,857 and 420 machines through S/N 224,882. This distinction helps identify when starter pinion backlash adjustment applies.

Breaker-point and condenser procedures apply to B43E, B43G, B48G, and T260 engines. P218G/P220G sections cover ignition coil wire identification, ignition module service, and magnetic ring replacement.

Engine service involves flammable fuel, rotating parts, and electrical starting circuits. Follow the manual's safety precautions and consult a qualified professional when a procedure exceeds your training.

A Preview of Valve, Camshaft and Rod Specifications

These examples represent a small selection of the manual's machining, clearance, and fastener data.

Valve seat work specifies a 45-degree seat angle. For B43E, B43G, and B48G engines, new-part camshaft gear backlash is 0.03–0.15 mm.

The connecting rod section lists cap nut torque at 18 ± 1 N·m for B43E, B43G, B48G, P218G, and P220G engines. T260 connecting rod cap screws are listed at 20 ± 1 N·m.

PDF Navigation and Included Pages

Text search and electrical illustrations: Searchable body text and embedded bookmarks provide access to service groups and individual procedures. Small labels in the starter-test connection diagrams and ignition-wire illustrations are best read with magnification.

Supplied as one printable, English-language 224-page PDF. That total includes one cover page, nine otherwise blank section-ending pages, and the two-page contents list at the back.