90-854785 Service Manual – Mariner 25HP 4-Stroke

The Mariner 25HP Service Manual (part number 90-854785) is the official factory guide for 4-stroke Mercury and Mariner outboards. Printed in the USA by Mercury Marine, it delivers accurate instructions for repair, service, and maintenance.

Inside, you’ll find clear diagrams, wiring schematics, and torque specifications. The manual also includes fuel system data, ignition adjustments, cooling system maintenance, and electrical testing procedures. Each section is organized for quick reference, so you can find the right information fast.

Step-by-step instructions guide you through oil pump assembly, rocker arm shaft service, and cylinder head installation. Troubleshooting charts help you identify issues and fix them without guesswork.

Written by the engineers who designed the engine, the Mariner 25HP Service Manual ensures every procedure matches original factory standards. This accuracy helps keep your engine running at peak performance and extends its life.

Whether you’re a marine mechanic or a hands-on boat owner, this workshop-ready manual is built to withstand oil, grease, and daily use. Arizona Outboard Dismantlers offers genuine manuals like this to help you protect your investment and keep your boating season trouble-free.