🏷️ Basic Information Identification Make: Mercury Mercruiser Model: Number 4 Stern Drive Units MCM 120 - 260 Year: 1978-1982 Product Type Product Name: Service Repair Workshop Manual Download 📋 Manual Details Manual Information Manual Type: Service Repair Workshop Manual Language: English File Information File Format: PDF Compatibility Operating Systems: All Versions of Windows & Mac Requirements Software Requirements: Adobe PDF Reader & WinZip Availability Download Type: Instant Download Illustration Quality Illustrations: Hundreds of photos and illustrations Usability Target Audience: Do-it-yourself-er and experienced mechanic Printability Printable Pages: All pages are printable ⚙️ Engine Specifications Model Codes Covered Engine Models: MCM 120, MCM 140, MCM 165, MCM 470, MCM 485, MCM 898, MCM 228, MCM 260 Engine Type Engine Configuration: Marine Inline-4, V6, V8 (depending on specific MCM model) Displacement Engine Displacement: Varies by MCM model (e.g., 3.7L for MCM 165, 4.3L for MCM 260) Power Horsepower Range: 120 HP to 260 HP (depending on MCM model) 🔧 Transmission Drive Unit Ratios Stern Drive Ratios: 1.98:1, 1.84:1, 1.65:1, 1.50:1 Drive Unit Type Drive Type: Stern Drive (Inboard/Outboard) 🔧 Maintenance Repair Scope Covered Procedures: General Information, Troubleshooting, Drive Unit, Drive Shaft Housing Assembly, Gear Housing Assembly, Transom Plate Assembly, Power Trim, Power Steering, Service Bulletins Repair Approach Disassembly Level: Complete dis-assembly Benefit Cost Effectiveness: Inexpensive way to keep vehicle working properly 📄 Technical Data Serial Number Ranges Transom Transom Serial Number Range: 4891650 - 6216686 Serial Number Ranges Drive Stern Drive Serial Number Ranges: 1.98:1 (4893635 - 6237860), 1.84:1 (4893835 - 6225576), 1.65:1 (4890460 - 6268064), 1.50:1 (4898730 - 6229157) Component Coverage Major Components Covered: Drive Unit, Transom Assembly, Power Trim, Power Steering