1994 Mercury 15 HP Super 15 Outboard Specs & Part Numbers
Introduction to the 1994 Mercury 15 HP Super 15
The 1994 Mercury 15 HP “Super 15” is a legendary two-stroke outboard motor revered by boaters, anglers, and marine mechanics alike. Renowned for its exceptional power-to-weight ratio, bulletproof reliability, and innovative design, this motor remains a highly sought-after model on the used market. Whether powering a utility jon boat, an inflatable tender, or a small fishing rig, the Super 15 delivers robust performance that rivals many modern four-stroke outboards in its class.
Overview & Technical Specifications
At the heart of the 1994 Mercury 15 HP Super 15 is a USA-designed, 2-cylinder, 262 cc (16.0 cubic inch) powerhead. The “Super 15” designation often denoted regional variations—such as the commercial-leaning SeaPro or Marathon configurations—which featured enhanced cooling systems, heavy-duty gearcases, and components tuned to deliver maximum low-end torque.
| Specification | Value / Detail |
|---|---|
| Propshaft Horsepower | 15 HP (11.2 kW) |
| Engine Type | 2-Stroke, Inline 2-Cylinder (Loop-Charged) |
| Displacement | 262 cc (16.0 cubic inches) |
| Bore & Stroke | 2.375 in x 1.812 in (60.3 mm x 46.0 mm) |
| Full Throttle RPM Range | 5000 – 6000 RPM |
| Fuel System | Single Carburetor with integral fuel pump |
| Fuel-to-Oil Ratio | 50:1 (87 Octane Unleaded Gas to TC-W3 2-Cycle Outboard Oil) |
| Starting System | Manual (Rope Start) / Electric optional on some sub-models |
| Dry Weight | Approx. 75 lbs (34 kg) for Short Shaft (15″) model |
Common Maintenance & Tune-Up Specs
Keeping a 1994 Mercury 15 HP running smoothly requires adherence to standard maintenance intervals. Because this engine utilizes a modern solid-state ignition system, traditional ignition adjustments are simplified.
Ignition & Electrical System
- Ignition Type: Modular CDI (Capacitor Discharge Ignition).
- Points Gap: Not Applicable (N/A). This motor utilizes a breakerless, solid-state CDI system, meaning there are no physical points to gap or wear out.
- Recommended Spark Plug: NGK BP8H-N-10 (Standard) or NGK BPZ8H-N-10 (Suppressed, used to prevent radio frequency interference).
- Spark Plug Gap: 0.040 inches (1.0 mm).
- Spark Plug Torque: 20 lb-ft (27 N·m).
Cooling & Water Pump
The water pump impeller is a critical wear item. If the engine is run in sandy, silt-heavy, or salty water, inspect and replace the impeller annually to avoid overheating.
- Impeller Part Number: Mercury OEM #47-42038-2 (or equivalent Sierra #18-3062).
- Thermostat Rating: 120°F (49°C) – ensures the engine reaches optimal operating temperatures quickly to prevent “cold fouling” of the plugs.
Gearcase Lubrication
- Lubricant Type: High-quality Marine SAE 90 Gear Lubricant (e.g., Mercury Premium Gear Lube).
- Gearcase Capacity: Approximately 6.8 fl oz (200 ml).
- Drain/Fill Screw Washers: Always replace the cardboard or nylon sealing washers (OEM #12-191833) when changing gear lube to prevent water intrusion.
Notable Features & History
The Genius of the Multi-Function Tiller Handle
Perhaps the most celebrated feature of this generation of Mercury outboards is the all-in-one multi-function tiller handle. Introduced in the late 1980s and perfected by 1994, this design integrated all vital operations into a single handgrip:
- Throttle: Twist the grip to accelerate.
- Shifting: Twist the grip past the idle detent to shift into Forward or Reverse. No more reaching back to the side of the engine cowl to find a shift lever.
- Stopping: The kill switch and push-button stop are integrated directly into the tip of the tiller.
- Friction Adjuster: A simple thumbwheel on the tiller allows the operator to adjust steering and throttle tension on the fly.
Loop-Charged Scavenging Design
Unlike older “cross-flow” 2-stroke outboards, the 262cc Mercury block utilized loop-charged scavenging. By directing the incoming fuel/air mixture in a loop pattern through precisely angled transfer ports, this motor achieved more complete combustion. The result was improved fuel economy, fewer smoky emissions, and crisp, instant throttle response.
The “Super 15” / Commercial Heritage
The “Super 15” label was heavily marketed in international, coastal, and commercial markets (often overlapping with the “Marathon” and “SeaPro” model lines). These units were designed to handle severe service duty. They featured corrosion-resistant components like stainless steel driveshafts, chrome-plated water pump housings, and extra zinc anodes to handle continuous brackish or saltwater immersion. Additionally, their heavy-duty transoms and robust clamp bracket assemblies made them popular choices for commercial fishermen and transport operators who demanded unmatched durability.