Mercury 90 Service Manual

4-0 - POWERHEAD 90-830234R3 DECEMBER 1997
Table of Contents
Page
Specifications 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tools for Powerhead Repair 4-2. . . . . . . . . . . . . . . . . . . . .
General Information 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Notes: 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft, Pistons and Connecting Rods
(3 Cyl.) 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Block (3 cyl.)
(USA-0G127499/BEL-9836632 & BELOW) 4-6. . . . . . . .
Cylinder Block (3 Cyl.)
(USA-0G127500/BEL-9836633 & UP) 4-10. . . . . . . . . . . .
Induction Manifold and Reed Block (3 Cyl.) 4-14. . . . . . .
Crankshaft, Pistons and Connecting Rods (4 Cyl.) 4-16.
Cylinder Block and Crankcase
(80 Jet/100/115/125) 4-18. . . . . . . . . . . . . . . . . . . . . . . . . . .
Induction Manifold and Reed Block
(80 Jet/100/115/125) 4-22. . . . . . . . . . . . . . . . . . . . . . . . . . .
Throttle Lever and Linkage
(65 Jet/75/90 Models) 4-24. . . . . . . . . . . . . . . . . . . . . . . . . .
Throttle Lever
(Models 80Jet/100/115/125) 4-26. . . . . . . . . . . . . . . . . . . .
Powerhead Removal 4-29. . . . . . . . . . . . . . . . . . . . . . . . . .
Flywheel Removal 4-34. . . . . . . . . . . . . . . . . . . . . . . . . .
Powerhead Disassembly 4-35. . . . . . . . . . . . . . . . . . . . . . .
Cleaning and Inspection 4-40. . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Block and Crankcase Cover 4-40. . . . . . . . .
Check Valves 4-42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Piston and Piston Rings 4-42. . . . . . . . . . . . . . . . . . . . .
Crankshaft 4-44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connecting Rods 4-44. . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Cover, Exhaust Divider Plate and
Exhaust Cover 4-45. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermostat 4-45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Switch Test 4-46. . . . . . . . . . . . . . . . . . . .
Reed Blocks 4-46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Page
Powerhead Reassembly and Installation 4-47. . . . . . . . .
General Information 4-47. . . . . . . . . . . . . . . . . . . . . . . .
End Cap 4-48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assembling Rod to Piston 4-48. . . . . . . . . . . . . . . . . . .
Piston Ring Installation 4-49. . . . . . . . . . . . . . . . . . . . . .
Crankshaft Installation 4-51. . . . . . . . . . . . . . . . . . . . . .
Connecting Rod Cap Alignment 4-54. . . . . . . . . . . . . .
Crankcase Cover to Block 4-55. . . . . . . . . . . . . . . . . . .
Cylinder Block Cover 4-56. . . . . . . . . . . . . . . . . . . . . . .
Exhaust Plate Cover and Exhaust Divider Plate 4-57
Intake Manifold and Reed Block Installation 4-59. . . .
Accelerator Pump Installation
(4 Cylinder Models) 4-60. . . . . . . . . . . . . . . . . . . . . . . . .
3 Cylinder Bleed Hose Routing 4-61. . . . . . . . . . . . . . . . . .
4 Cylinder Bleed Hose Routing (1995 and Prior) 4-62. . .
4 Cylinder Bleed Hose Routing
(1996 and Newer) 4-63. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Cylinder Fuel Enrichment/Accelerator Pump Hose
Routing 4-64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1994 and Newer 3 Cylinder Harness Routing (without
Oil Reservoir Installed) 4-65. . . . . . . . . . . . . . . . . . . . . . . . .
1994 and Newer 3 Cylinder Harness Routing
(with Oil Reservoir Installed) 4-66. . . . . . . . . . . . . . . . . . . .
3 Cylinder Manual Start Harness Routing 4-67. . . . . . . . .
1994 and Newer 4 Cylinder Harness Routing (without
Oil Reservoir Installed) 4-68. . . . . . . . . . . . . . . . . . . . . . . . .
1994 and Newer 4 Cylinder Harness Routing
(with Oil Reservoir Installed) 4-69. . . . . . . . . . . . . . . . . . . .
Ignition Plate Installation 4-70. . . . . . . . . . . . . . . . . . . .
Trigger and Stator Installation 4-71. . . . . . . . . . . . . . . .
Stator Installation 4-72. . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature Sensor Installation 4-74. . . . . . . . . . . . . .
Carburetor Installation 4-74. . . . . . . . . . . . . . . . . . . . . .
Flywheel Installation 4-76. . . . . . . . . . . . . . . . . . . . . . . .
Oil Reservoir Installation 4-76. . . . . . . . . . . . . . . . . . . .
Air Box Installation 4-77. . . . . . . . . . . . . . . . . . . . . . . . . .
Powerhead to Driveshaft Housing 4-78. . . . . . . . . . . .
Reinstall Bottom Cowl 4-79. . . . . . . . . . . . . . . . . . . . . . .

Mercury 90 Specifications

General

Brand	Mercury
Model	90
Category	Outboard Motor
Language	English