1998 Mercury Mariner 20 JET, 20, 25, 25 MARATHON und 25 SEAPRO Outboard Motor Service Manual
Technical reference spanning Mercury Mariner 20 JET, 20, 25, 25 MARATHON, and 25 SEAPRO models, covering engine specifications, maintenance, and electrical systems. Includes part numbers like 92-78376A6.
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Sample pages from the 1998 Mercury Mariner 20 JET, 20, 25, 25 MARATHON und 25 SEAPRO Outboard Motor Service Manual manual
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Mercury Models Covered & Key Technical Specifications
Models: Mercury/Mariner 20 JET, 20, 25, 25 MARATHON, 25 SEAPRO
Sub-models / Variants: 15XD, Short Shaft, Long Shaft, Electric Start, Remote Control, Manual Start, Tiller Handle, Side Shift
Build Years: 1994–1999
Serial Numbers: United States: 0G044027 and Above, Belgium: 09807909 and Above
Technical Data:
- Engine: Two-cylinder, two-cycle
- Displacement: 24.4 cu. in. (400 cc)
- Horsepower: 20 HP (14.9 kW) to 25 HP (18.7 kW)
- Gear Ratio: 2.25:1
- Ignition Type: Capacitor Discharge Ignition (CDI)
- Spark Plug: NGK BP8H-N-10
- Spark Plug Gap: 0.040 in. (1.0 mm)
- Fuel/Oil Ratio: 50:1
- Charging System Output: 4–6 Amps @ 6000 RPM
- Battery Rating: 465 MCA / 350 CCA
Mercury Manual Features & Content Preview
Mercury Mariner 20 JET, 20, 25, 25 MARATHON, 25 SEAPRO Service Manual
- Covers 1994–1999 Mercury/Mariner 20 HP and 25 HP outboard motors, including 20 JET, Marathon, and SeaPro variants
- Official OEM publication P/N 90-826883R2, published June 1998
- Includes over 45 detailed technical schematics, exploded-view diagrams, and electrical wiring configurations
- Stored against your account so you can retrieve it after a hard-drive loss
- Full-text search finds any part number in seconds
- This edition is the definitive factory reference for the transition from the earlier 20-series ignition to the updated 1997+ mechanical advance systems
Technical Scope and Documentation
This factory service publication provides technical coverage for the Mercury Mariner 20 and 25 HP two-cycle outboard engine series. Chapters detail the specifications and service parameters for the powerhead, mid-section, and lower unit. The content documents maintenance schedules for salt-water and fresh-water operation, including cooling system flushing, fuel line inspection, and corrosion anode replacement. Special emphasis is placed on identifying serial-number-specific ignition components, as these units utilize differing charging and ignition trigger systems based on the production year and model variant.
Electrical and Performance Specifications
Engine timing values, spark plug specifications, and stator winding resistance readings are documented for the various ignition systems employed throughout the production run. The manual includes comprehensive electrical troubleshooting flow charts for starter circuits and battery charging systems. Fluid capacity for the 2.25:1 gear ratio housing is specified at 8.8 fl. oz. (260 ml). Cylinder bore diameter is listed at 2.562 in. (65.01 mm). Ignition coil resistance for the 20/25 1997/98 models is documented at 0.02–0.04 ohms (primary) and 8000–11000 ohms (secondary). Reference this publication for how factory workshop documentation is structured to manage ongoing maintenance.
Reference only — always consult a certified technician before performing service on this equipment.
An official 337-page Mercury Marine factory workshop manual covering the 1994–1999 20 and 25 HP outboards, documenting engine, chassis, electrical, and fuel-system specifications for the JET, Marathon, and SeaPro production builds.
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