Mercury Mercruiser Sterndrives R MR Alpha One Alpha One SS 1983 1984 1985 1986 1987 1988 1989 1990 Factory Service Repair Manual

Mercury Mercruiser Sterndrives R MR Alpha One Alpha One SS 1983 1984 1985 1986 1987 1988 1989 1990 Factory Service Repair Manual

Loaded with illustrations, instructions, photos, and diagrams, complete to service and repair your Mercury. 

566  Pages

MODELS COVER:

STERNDRIVE (MCM)

MC 120R/140B/185R/488R/898R/228R/260R

Serial.: 6216687 – 6849289

MC 120MR/140MR/170MR/185MR/190MR/200MR/

230MR/260MR/300 Tempest MR

Serial.: 6849290 – 0A471374

MC Alpha One/Alpha One SS

Serial.: 0A471375 and Above

MANUAL COVERS:

Section 1 – Important Information

A – Important Information

B – Maintenance

C – Troubleshooting

Section 2 – Removal, Installation and Adjustments

A – All Models

Section 3 – Sterndrive Unit

A – Drive Shaft Housing

B – Gear Housing – MR/Alpha One/Alpha One SS

C – Gear Housing – I-R

D – Gear Housing – Alpha One Counter Rotation

Section 4 – Transom Assembly

A – Service Procedures Requiring Minor

Disassembly

B – Service Procedures Requiring Major

Disassembly

Section 5 – Power Trim

A – Oildyne Power Trim Pump (Plastic Reservoir)

B – Oildyne Power Trim Pump (Aluminum Reservoir)

C – Prestolite Power Trim Pump

D – Trim Cylinders

E – Dual Power Trim Control

F – Auto Trim II

Section 6 – Steering Systems

A – Power Steering

B – Manual Steering

Section 7 – Corrosion Protection

A – All Models

This manual is the same as the manual used by workshops. Service Manual contains detailed instructions and step by step diagrams for all workshop procedures.

 Language: English 
Format: PDF

COMPATIBLE WITH ALL WINDOWS & MAC COMPUTERS 
(WINDOWS 11, WINDOWS 10, WINDOWS 8 ETC.) 

Windows/Mac/Tablet/Phone Friendly

• Production: The R drive was produced from 1983–1984, while the MR drive was made from 1984–1985.
• Features:
  • MR update: The MR version introduced design changes for greater durability, including a stronger gear housing with reverse spiral-cut gears and a new driveshaft bearing.
  • Identification: An “A” stamped on the end of the prop shaft was used to differentiate the MR drive from the older R drive. 

• Production: Introduced in 1986 and produced until 1990 before being replaced by the Gen II model in 1991.
• Features:
  • Performance: The Alpha One Gen I delivered reliable performance and an efficient hydrodynamic profile that produced minimal drag.
  • Shift system: Featured a smooth-shifting gear system.
  • Water pump: Used a water pump with a plastic housing.
  • Lube monitoring: Included an audible low-lube warning alarm for enhanced durability.
  • Serviceability: Designed for easier routine service compared to older models. 

• Production: Built from 1986 to 1989.
• Features:
  • High performance: Intended for speed-focused boats, with a lower-profile gearcase for reduced drag and higher speeds.
  • Drive differences: Like the standard Alpha One, it featured a stronger lower unit compared to the older R and MR drives.

• Preload pin: R and MR drives have a preload pin on the top of the driveshaft, which was eliminated on the Alpha One.
• Water pump housing: Alpha One Gen I drives use a plastic water pump housing, distinguishing them from the Gen II drives that came later.
• Gen I vs. Gen II: The Alpha One Gen I has a skeg with a vertical trailing edge, while the Gen II (from 1991 onward) has a skeg that angles toward the prop.