This comprehensive service repair manual provides a complete guide for working on Mercury Mercruiser #6 Sterndrive Units R, MR, Alpha One, and Alpha One SS, covering model years 1983 through 1990. The manual includes detailed service and repair procedures, covering disassembly, assembly, and adjustments. It also includes wiring diagrams and essential troubleshooting information. The manual features a wealth of information, including specifications, diagrams, and real photographs to illustrate every step. It guides you through every aspect of repair, diagnostics, servicing, technical maintenance, and troubleshooting for your Mercury Mercruiser #6 sterndrive units. With this manual, you'll have everything you need to confidently tackle repairs, saving time and money. The manual covers a wide range of models, including: * **Transom Assemblies:** MC 120R / 140B / 185R / 488R / 898R / 228R / 260R, MC 120MR / 140MR / 170MR / 185MR / 190MR / 200MR / 230MR / 260MR / 300 Tempest MR, and MC Alpha One / Alpha One SS. * **Sterndrive Units:** MC 120R-260R and MC 120 MR - 300 TEMPEST MR, with breakdowns by original and serviced gear ratios and corresponding serial numbers. * **MC Alpha One / Alpha One SS:** Detailed breakdowns by original and serviced gear ratios, with separate serial numbers for right and left-hand models. * **Sea Ray Sterndrive Units and Transom Assembly (Oyster White):** Covers Sea Ray models with corresponding MerCruiser equivalents, and includes gear ratio and serial number information. The manual is organized into seven sections: * **Important Information:** This section covers essential information, including maintenance tips and troubleshooting advice. * **Removal, Installation, and Adjustments:** This section provides step-by-step instructions for removing, installing, and adjusting various components across all models. * **Sterndrive Unit:** This section covers components specific to the sterndrive unit, including the drive shaft housing, gear housing for different models, and counter rotation components. * **Transom Assembly:** This section details procedures requiring both minor and major disassembly of the transom assembly. * **Power Trim:** This section provides detailed information on Oildyne and Prestolite power trim pumps, trim cylinders, dual power trim control, and Auto Trim II. * **Steering Systems:** Covers both power and manual steering systems. * **Corrosion Protection:** Provides comprehensive information on corrosion protection for all models.

The Mercury Mercruiser #6 Sterndrive Units R, MR, Alpha One, and Alpha One SS, a staple in the boating industry from 1983 to 1990, represent a range of powerful and reliable sterndrive units designed for recreational boats. These units, known for their robust construction and versatility, were widely adopted by boat manufacturers and enthusiasts alike. The Mercruiser #6 series encompasses a variety of configurations, with the "R" and "MR" designations indicating different gear ratios and options. The Alpha One and Alpha One SS models, however, represent specific sterndrive configurations with distinct features. The Alpha One, a standard sterndrive unit, boasts a durable and efficient design, while the Alpha One SS, an upgrade, offers enhanced performance and durability with features like a stainless steel prop shaft and upgraded components. These units equipped boats of various sizes and types, from sleek cruisers to fishing boats, providing reliable power and maneuverability on the water. The Mercruiser #6 Sterndrive units were renowned for their integrated design, coupling a powerful engine with a compact and efficient drive system. The system's components, including the engine, transmission, and drive unit, worked seamlessly together to deliver smooth and responsive performance. These units offered a range of engine options, enabling boat owners to choose the power and efficiency to suit their needs. The Mercruiser #6 series was also praised for its ease of maintenance and repair, with readily available parts and extensive repair manuals, including the one mentioned - "Mercury Mercruiser #6 Sterndrive Units R MR Alpha One Alpha One SS Service Repair Manual 1983-1990," which provided detailed information to help users troubleshoot and repair issues. Though these units are no longer in current production, their legacy lives on, with many still in operation today, offering reliable service and enjoyment for boat owners.