1965–1991 Mercury 2.2–40 HP Outboard Service & Repair Manual

This Mercury outboard service and repair manual covers single- and twin-cylinder two-stroke engines in the 2.2–40 HP range, with model-specific tuning and repair sections for 1965–1991 applications.

• Powerhead repair: Removal, split-block disassembly, piston and crankshaft inspection, reed service, cylinder honing, reassembly, and installation for the three powerhead layouts.

• Fuel system: Carburetor overhaul, fuel-delivery troubleshooting, pump testing, idle adjustments, and Auto Blend oil-injection checks.

• Ignition and timing: Phelon magneto, Thunderbolt Phase Maker, and CD ignition diagnosis, with separate timing and carburetor synchronization procedures.

• Lower unit and cooling: Gearcase disassembly, shaft and bearing service, gear shimming, shift adjustments, seal replacement, and water-pump impeller service.

• Trim and tilt: Mechanical tilt adjustment, hydraulic bleeding, electrical troubleshooting, cylinder service, and hydraulic pump and motor repair.

• Controls and starting: Commander shift-box repair, electric starter testing and overhaul, and illustrated identification and service procedures for eight hand rewind starter types.

Suited to owners and mechanics who understand two-stroke operation and have access to a torque wrench, electrical test equipment, and the service tools required for the work.

Powerhead Repair and Routine Care

The powerhead chapter separates split-block engines by reed arrangement and cylinder-head design. Internal reed work on Types A and C requires powerhead disassembly, while Type B uses an external reed block. That distinction helps you assess the repair scope before opening the engine.

Inspection coverage extends to connecting rods, crankshaft bearings, pistons, cylinder wear, and honing. The maintenance chapter adds preseason preparation, winter storage, submerged-engine service, and lubrication schedules that distinguish fresh-water from salt-water use.

Carburetors, Fuel Delivery, and Auto Blend

The fuel chapter separates the Mikuni rectangular- and round-bowl designs, Tillotson BC, Walbro WM, and Keihin-equipped carburetors. Exploded views accompany the overhaul sections, with float, inlet-needle, diaphragm, and adjustment information appropriate to each design.

Troubleshooting distinguishes rough idle from fuel starvation and engine surge, including restrictions between the tank and carburetor. The fuel-pump test section identifies the pumps on Models 3.5, 3.6, and 4.0 as replacement items rather than rebuildable assemblies.

Auto Blend coverage includes operation, low-oil warning checks, troubleshooting, storage, and preparation for use.

Ignition Diagnosis and Synchronization

Separate sections explain Phelon magnetos, Phase Maker systems with and without an electrical module, and Thunderbolt CD arrangements. Stator and coil check tables identify test connections and meter scales; timing sections distinguish applications such as Models 200, 402, and 110.

The Phase Maker discussion explains why roughened or discolored contacts alone do not establish that the points need replacement. Flywheel-service cautions also address damage from rim-type pullers and from hammering the puller against the crankshaft.

Wiring coverage includes the Model 350 electric-start diagram and configurations with manual starting, alternators, and remote controls.

Gearcase and Water-Pump Service

Lower-unit procedures cover the shafts, bearings, clutch and shift components, seals, and water pump. Gear shimming and backlash checks are organized by lower-unit design, with tool references such as Cover Nut Tool C-91-74588.

The appendix brings together the carburetor jet size/elevation chart, gear backlash table, component torque tables, and metric conversion chart.

Trim, Tilt, and Commander Controls

Hydraulic coverage extends beyond bleeding to pump testing, cylinder inspection, solenoid checks, and electric motor service. The precision-fitted valve-body/gear-cage and control-valve assemblies are treated as complete replacement units.

The remote-control repair chapter is specific to Commander shift boxes. Hand rewind starters are identified by illustrated construction details, with separate procedures for their spring, sheave, pawl, and interlock arrangements.

Secure the outboard properly, isolate electrical power before disassembly, and handle fuel in a well-ventilated area.

A Preview of Gearcase Capacities and Backlash Data

The lower-unit oil chart lists 5.50 fl oz for Model 18 and 7.60 fl oz for Model 18XD, distinguishing the capacities of these closely named variants.

For gear setup, the Model 35 forward-gear backlash specification is 0.007–0.010 in., while Model 350 is listed at 0.003–0.005 in. The table also identifies the lower-unit type associated with each entry.

PDF Bookmarks, Wiring Detail, and Page Count

Navigation and diagram detail: Embedded bookmarks provide access to the chapters, appendix, and wiring section. PDF text search is unavailable. Small wiring labels require zooming; enlarged views allow the wire-color codes and connector markings to be read.

One printable English-language PDF contains 520 pages, including five contents pages and the 51-page appendix. These pages are already included in the total.