1987-1993 Mercury Mariner 70/75/80/90/100/115 HP Outboards OEM Service & Repair Manual

(3 Cylinder) UNITED STATES S/N 0A996142 thru 0D283221 BELGIUM S/N 09502135 thru 09793576 CANADA S/N 0A722297 and Above BELGIUM CANADA S/N 0B209468 thru 0D283221 S/N 09523034 thru 09793576 S/N 0A731673 and Above MODELS 70 • 75 • 80 • 90 • 100 • 115 SERVICE MANUAL 1987–1993 70 • 75 • 75 Marathon • 75XD • 75 Seapro • 80 • 90 1988–1993 100 • 115 (4 Cylinder) with Serial Numbers with Serial Numbers UNITED STATES Printed in U.S.A. 1995, Brunswick Corporation 90-13645--2 1095

Notice Throughout this publication, “Dangers”, “Warnings” and “Cautions” (outlined in a border and accompa- nied by the International HAZARD Symbol ) are used to alert the mechanic to special instructions concerning a particular service or operation that may be hazardous if performed incorrectly or carelessly. OBSERVE THEM CAREFULLY! These “Safety Alerts” alone cannot eliminate the hazards that they signal. Strict compliance to these special instructions when performing the service, plus “common sense” operation, are major accident prevention measures. DANGER DANGER — Immediate hazards which WILL result in severe personal injury or death. WARNING WARNING - Hazards or unsafe practices which COULD result in severe personal injury or death. CAUTION — Hazards or unsafe practices which could result in minor personal injury or product or property damage. CAUTION Notice to Users of This Manual This service manual has been written and published by the service department of Mercury Marine to aid our dealers’ mechanics and company service personnel when servicing the products described herein. It is assumed that these personnel are familiar with the servicing procedures of these products, or like or similar products manufactured and marketed by Mer- cury Marine, that they have been trained in the recommended servicing procedures of these products which includes the use of mechanic’s common hand tools and the special Mercury Marine or recommended tools from other suppliers. We could not possibly know of and advise the service trade of all conceivable procedures by which a service might be performed and of the possible hazards and/or results of each method. We have not under- taken any such wide evaluation. Therefore, anyone who uses a service procedure and/or tool, which is not recommended by the manufacturer, first must completely satisfy himself that neither his nor the product’s safety will be endangered by the service procedure selected. All information, illustrations and specifications con- tained in this manual are based on the latest product information available at the time of publication. As re- quired, revisions to this manual will be sent to all dealers contracted by us to sell and/or service these products. It should be kept in mind, while working on the product, that the electrical system and ignition system is capable of violent and damaging short circuits or severe electrical shocks. When performing any work where electrical terminals could possibly be grounded or touched by the mechanic, the battery cables should be disconnected at the battery. Any time the intake or exhaust openings are exposed during service they should be covered to protect against accidental entrance of foreign material which could enter the cylinders and cause extensive internal damage when the engine is started. It is important to note that, during any maintenance procedure, replacement fasteners must have the same measurements and strength as those removed, whether metric or customary. Numbers on the heads of the metric bolts and on surfaces of metric nuts indicate their strength. Customary bolts use ra- dial lines for this purpose, while most customary nuts do not have strength markings. Mismatched or incor- rect fasteners can result in damage or malfunction, or possible personal injury. Therefore, fasteners removed should be saved for re-use in the same locations whenever possible. Where the fasteners are not satisfactory for re-use care should be taken to select a replacement that matches the original.

Cleanliness and Care of Outboard Motor A marine power product is a combination of many machined, honed, polished and lapped surfaces with tol- erances that are measured in the ten thousands of an inch. When any product component is serviced, care and cleanliness are important. Throughout this manual, it should be understood that proper cleaning, and protection of machined surfaces and friction areas is a part of the repair procedure. This is consid- ered standard shop practice even if not specifically stated. Whenever components are removed for service, they should be retained in order. At the time of installation, they should be installed in the same locations and with the same mating surfaces as when removed. Before raising or removing an outboard engine from a boat, the following precautions should be adhered to: 1. Check that flywheel is secured to end of crankshaft with a locknut and lifting eye is threaded into flywheel a minimum of 5 turns. 2. Connect a hoist of suitable strength to the lifting eye. In addition, personnel should not work on or under an engine which is suspended. Engines should be at- tached to work stands, or lowered to ground as soon as possible. We reserve the right to make changes to this manual without prior notification. Refer to dealer service bulletins for other pertinent information concerning the products described in this manual. Service Manual Outline 1 - General Information and Specifications 2 - Electrical and Ignition A - Ignition System B - Battery, Charging System and Starting System C - Timing/Synchronizing and Adjusting D - Wiring Diagrams 3 A - Fuel System and Carburetion B - Oil Injection System 4 A - Powerhead (3-Cylinder Engines) B - Powerhead (4-Cylinder Engines) 5 - Lower Unit A - Gear Housing B - Mid Section C - Shock Absorber 6 - Power Trim A - Design I (Side Fill Reservoir) B - Design II (Aft Fill Reservoir) C - Single Ram 7 - Outboard Motor Installation/Attachments A - Engine Attachments/Engine Installation B - Tiller Handle and Co-Pilot

GENERAL INFORMATION AND SPECIFICATIONS 1

90-13645-2 495 Table Of Contents Page Page General Specification 1-1 . . . . . . . . . . . . . . . . . . . . . . Cowl Removal 1-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . Filling Oil Injection System 1-3 . . . . . . . . . . . . . . . . . . Power Trim General Information 1-4 . . . . . . . . . . . . . Trim “In” Angle Adjustment 1-4 . . . . . . . . . . . . . . . . . Models with Power Trim 1-4 . . . . . . . . . . . . . . . . Checking Trim System Fluid Level 1-5 . . . . . . . . . . . Tilt Angle Adjustment 1-5 . . . . . . . . . . . . . . . . . . . . . . Models without Power Trim 1-5 . . . . . . . . . . . . . . Connecting Engine Wiring Harness and Routing of Engine Battery Cables 1-6 . . . . . . . . Ride-Guide Steering Cable and Pivot Points Lubrication 1-7 . . . . . . . . . . . . . . . . . Following Complete Submersion 1-8 . . . . . . . . . . . . Salt Water Submersion (Special Instructions) 1-8 . . . . . . . . . . . . . . . . Submerged While Running (Special Instructions) 1-8 . . . . . . . . . . . . . . . . Submerged Engine (Fresh Water) (Plus Special Instructions) 1-8 . . . . . . . . . . . Out-of-Season Outboard Storage 1-9 . . . . . . . . . . . How Weather Affects Engine Performance 1-10 . . Conditions Affecting Operation 1-11 . . . . . . . . . . . . . Detonation: Causes and Prevention 1-12 . . . . . . . . Compression Check 1-12 . . . . . . . . . . . . . . . . . . . . . .

1-1 90-13645--2 1095 GENERAL INFORMATION AND SPECIFICATIONS General Specification NOTE: Other specification (torques, etc.) are listed in the respective sections. Model 70 Model 75 Model 80 Model 90 Horsepower 70 (52.2 kw) 75 (55.9 kw) 80 (59.6 kw) 90 (67.1 kw) Idle RPM (in forward gear) 650 - 700 Full Throttle RPM Range 4750 - 5250 5000 - 5500 Piston Replacement 71.12 (1165.7cc) Cylinder Bore 3.375 (85.7mm) Stroke 2.65 (67.3mm) Engine Type 3 Cylinder, 2 Cycle Ignition Type C.D. Breakerless Recommended Spark Plug NGK-BUHW-2 or AC-V40 FFK or Champion L78V Inductor Plugs: NGK-BUZHW-2 or Champion QL78V Cylinder Firing Order 1-3-2 Recommended Power Trim Fluid Quicksilver Power Trim & Steering Fluid or Automotive Transmission Fluid (ATF) Type F, FA or Dexron II Recommended Gasoline Regular Leaded, Premium, Low-Lead and Lead-Free automotive gaso- lines with a minimum pump posted octane rating of 86 Recommended Oil Quicksilver TC-WII or TC-W3 2-Cycle Outboard Oil Engine Weight ELO ELOPT 260 lbs. 280 lbs. Fuel Tank Capacity 6.6 U.S. Gallons (5 Imp. Gals.; 25 Liters) Gear Housing Lubricant Capacity 22.5 fl. oz. (665.3ml) Gasoline/Oil Ratio at Idle 80:1 Gasoline/Oil Ratio at W.O.T. 50:1 Gear Ratio 2.3:1 Oil Injection Tank Capacity Tank Capacity 1 gal. (3.78 liter) Maximum operation per tank full of oil at W.O.T. 6 hours Oil remaining when warning buzzer sounds 1 qt. (.95 liter) Operating time remaining at wide open throttle when warning buzzer sounds 1 Hour

1-2 90-13645--2 1095 GENERAL INFORMATION AND SPECIFICATIONS General Specification (continued) NOTE: Other specification (torques, etc.) are listed in the respective sections. Model 100 Model 115 Horsepower 100 (74.6 kw) 115 (85.8 kw) Idle RPM (in forward gear) 650 - 700 Full Throttle RPM Range 4750 - 5250 Piston Replacement 105 (1720.9cc) Cylinder Bore 3.375 (85.7mm) Stroke 2.930 (74.4mm) Engine Type 4 Cylinder, 2 Cycle Ignition Type C.D. Breakerless Recommended Spark Plug NGK-BPH8H-N-10* Gap - 0.040 in. (1.0mm) Inductor Plug NGK BPZ 8H-N-10* Gap - 0.040 in. (1.0mm) NGK-BUHW Cylinder Firing Order 1-3-2-4 Recommended Power Trim Fluid Quicksilver Power Trim & Steering Fluid or Automotive Transmission Fluid (ATF) Type F, FA or Dexron II Recommended Gasoline Regular Leaded, Premium, Low-Lead and Lead-Free automotive gaso- lines with a minimum pump posted octane rating of 86 Recommended Oil Quicksilver 2-Cycle Outboard Oil Engine Weight ELO ELOPT 340 lbs. 360 lbs. Fuel Tank Capacity 6.6 U.S. Gallons (5 Imp. Gals.; 25 Liters) Gear Housing Lubricant Capacity 22.5 fl. oz. (665.2ml) Gasoline/Oil Ratio at Idle 80:1 Gasoline/Oil Ratio at W.O.T. 50:1 Gear Ratio 2.07:1 Oil Injection Tank Capacity Tank Capacity 1.4 gal. (5.3 liters) Maximum operation per tank full of oil at W.O.T. 5 hours Oil remaining when warning buzzer sounds 1 qt. (.95 liter) Operating time remaining at wide open throttle when warning buzzer sounds 50 min. approx. *Improves running quality between 1800 – 2000 RPM.

90-13645--2 495 1-3 GENERAL INFORMATION AND SPECIFICATIONS Cowl Removal Pull outward on starboard side of front shield (a). Remove spring (b) from latch and open cowls. 18291 a 18292 b Filling Oil Injection System Open starboard cowl (refer to cowl removal on this page). Some earlier outboards will have a cowl brack- et to hold cowl open as shown. Fill tank with recommended oil. a a - Oil Tank Tube

1-4 90-13645--2 495 GENERAL INFORMATION AND SPECIFICATIONS Power Trim System GENERAL INFORMATION The power trim system is filled at the manufacturer and is ready for use. Trim outboard through entire trailering range several times to remove any air from the system. The trim system is pressurized and is not externally vented. The outboard can be raised or lowered manu- ally by loosening the manual release valve four turns. The trim “out” angle of this outboard is not adjustable. The trim system has an internal valve which will automatically stop the outward trim travel at 20_ when engine RPM is approximately 2000 RPM or higher; outboard also has to be in water and in gear. The outboard can be operated beyond the 20_ trim limit for operating outboard in shallow water if engine RPM is kept below approximately 2000 RPM. a b 23321 a - Fill Screw (System is Pressurized, DO NOT Open Unless Outboard is Tilted to Full Up Position) b - Manual Release Valve Trim “In” Angle Adjustment MODELS WITH POWER TRIM WARNING Operating some boats with outboard trimmed to the full “in” trim angle [not using trim adjustment bolt (a)] at planing speed will cause undesirable and/or unsafe steering conditions. Each boat MUST BE water tested for handling characteristics after outboard installation and after any trim adjust- ments. IMPORTANT: Some boat/motor combinations, that do not use the trim adjustment bolt (a) and are trimmed to the full “in” trim angle, will not experi- ence any undesirable and/or unsafe steering conditions during planing speed. Thus, not using trim adjustment bolt may be desired. However, some boats with outboard trimmed to the full “in” trim angle at planing speeds will cause undesirable and/or unsafe steering conditions. If these steering conditions are experienced, under no circumstances should the outboard be operated without the trim adjustment bolt and without the bolt adjusted in the proper holes to prevent unsafe handling characteristics. Water test the boat not using the trim adjustment bolt. If undesirable and/or unsafe steering conditions are experienced (boat runs with nose down), install trim adjustment bolt in proper hole to prevent unsafe handling characteristics. 22744 a

90-13645--2 495 1-5 GENERAL INFORMATION AND SPECIFICATIONS Checking Trim System Fluid Level IMPORTANT: This trim system is pressurized. Remove fill screw (b) when outboard is trimmed to the full “up” position. Retighten fill screw securely. 1. Trim outboard to full “up” position. Engage tilt lock lever. Trim system fluid can only be checked when outboard is in this position. 2. Remove fill screw and check fluid level. Fluid level should be visible in fill tube. 3. If necessary, add Quicksilver Power Trim and Steering Fluid; or Automatic Transmission Fluid (ATF) Type F, FA or Dextron II. 20319 a b a - Tilt Lock Lever b - Fill Screw Tilt Angle Adjustment MODELS WITHOUT POWER TRIM WARNING Operating some boats at minimum trim “In” at planing speeds will cause undesirable and/or unsafe steering conditions. Each boat should be tested for handling characteristics after any adjustment is made to the tilt angle. DO NOT OPERATE motor with tilt lock pin removed. Adjust tilt angle of motor on transom with tilt lock pin so that anti-ventilation plate is about parallel and even with bottom of boat. Speed sometimes may be im- proved by tilting motor out one tilt pin hole to raise bow and reduce wetted surface. If motor is tilted in, boat will ride bow down, wetting more of the bottom and re- ducing speed, which generally will improve operation in rough water. Under ideal conditions, efficiency is best with lower unit operating in level position. Opera- tion with excessive tilt angle will reduce performance noticeably and may induce ventilation. It is preferable to level boat by proper loading rather than by extreme adjustment of tilt angle. 22744 a a - Tilt Lock Pin

1987-1993 Mercury Mariner 70/75/80/90/100/115 HP Outboards OEM Service & Repair Manual

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