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25 MARATHON
Mercury/Mariner 25 MARATHON User Manual
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MODELS
United States
0G044027 and Above
. . . . . . .
Belgium
09807909 and Above
. . . . . . . . . . .
With Serial Numbers
S
E
R
VICE
MANUAL
20 JET
20
25
Mercury/Mariner
25 MARA
THON
25 SEAPRO
Printed in U.S.A.
1998, Mercury Marine
90-826883R2 JUNE 1998
2
Table of Contents
Important Information 1
10
Table of Contents
10
After each Use
12
Before each Use
12
Every 100 Hours of Use or Once Yearly, Whichever Occurs First
12
Every 300 Hours of Use or Three Years
12
Inspection and Maintenance Schedule
12
Flushing the Cooling System
13
Fuel System
14
Fuel Line Inspection
14
Engine Fuel Filter
14
Corrosion Control Anode
15
Battery Inspection
16
Spark Plug Inspection
16
Fuse Replacement -- Electric Start Remote Control Models
17
Lubrication Points
17
Gear Case Lubrication
19
Gear Case Lubricant Capacity
19
Draining Gear Case
19
Draining Gear Case
20
Checking Lubricant Level and Refilling Gear Case
20
Storage Preparations
21
Fuel System
21
Protecting External Engine Components
21
Protecting Internal Engine Components
21
Gear Case
22
Positioning Outboard for Storage
22
Battery Storage
22
Propeller Selection
27
Important Information 1
35
Outboard Remote Control
36
Selecting Accessories for the Outboard
36
Selecting Steering Cables and Remote Control Cables
36
Installing Outboard
37
Steering Cable and Steering Link Rod Installation 1D-4
38
Installing Ride Guide Steering Cable to the Outboard
38
Steering Cable Seal
38
Steering Link Rod Installation
39
Remote Control Installation
40
Shift and Throttle Cable Installation to the Outboard
40
Shift Cable Installation
40
Throttle Cable Installation
41
Remote Wiring Harness Connection to Engine
42
Battery Cable Connections
44
Propeller Installation
44
Tilt Pin Adjustment
45
Placing Tilt Pin in Lower Holes
45
Placing Tilt Pin in Upper Holes
46
Trim Tab Adjustment
46
Electrical 2
47
Specifications
48
Special Tools
49
Ignition/Electrical Components
50
Ignition Description
52
Electronic Spark Advance
53
Mechanical Spark Advance
53
Ignition Component Description
53
Trigger Coil
53
Stator
54
Flywheel
54
Ignition Coil
55
Ignition Switch Box
55
Electronic Spark Advance
57
Ignition Test Procedures
58
Direct Voltage Adapter (DVA)
58
Ignition Diagnostic Procedures
59
Electronic Spark Advance
61
Tool: Multimeter/Dva Tester 91-99750A1
61
Mechanical Spark Advance
62
Ignition Troubleshooting
59
Ignition Troubleshooting (RED Stator)
63
Electrical 2
64
Electric Start Components
65
Battery
67
Precautions
67
Recommended Battery
67
Operating Engine Without Battery
67
Specific Gravity Readings
67
Electrolyte Level
68
Charging a Discharged Battery
69
Winter Storage of Batteries
69
Battery Charging System
70
Description
70
Alternator Amperes Output
71
Battery Charging System Troubleshooting
72
Alternator Test
72
Rectifier Test
73
Voltage Regulator Test
70
Lamps Burn out When Engine RPM Is Increased
70
Lamps Burn DIM at Wide-Open-Throttle
70
Starting System
74
Starter Motor Amperes Draw
74
Starting System Components
74
Description
74
Troubleshooting the Starting Circuit
74
Commander 2000 Key Switch Test
77
Emergency Stop Switch
78
(Lanyard Type)
78
Push Button Stop Switch
78
Starter Motor
79
Disassembly
79
Cleaning and Inspection
80
Testing Motor Armature
81
Starter Motor Reassembly
82
Starter Solenoid Test
84
Flywheel Ring Gear
85
Installation
85
Neutral Start Switch (Electric Start Tiller Handle Shift Models)
86
Tiller Handle Start Button
87
Choke Solenoid
88
Installation
88
Battery Cables/Engine Wiring Harness (Remote Electric Start Models)
89
Battery Cables (Tiller Handle Push Button Electric Start Models)
92
Installation
92
Emergency Stop Switch (Lanyard Type)
94
Plug Harness (Battery Charging Kit)
94
Installation
94
Electrical 2
95
Special Tools
96
Timing/Synchronizing
97
Side Shift Models: Adjusting Tiller Handle
98
Tiller Shift Models: Adjusting Link Rod
99
Starting Procedure
100
Timing Checking and Adjustment
100
Adjusting Idle Speed
102
Timing/Synchronizing/Adjusting - Remote Control Models
104
Shift and Throttle Cable Installation to the Outboard
107
Shift Cable Installation
108
Throttle Cable Installation
109
Starting Procedure
110
Adjusting Idle Speed
111
Electrical 2
112
Manual Start Models (Electronic Advance)
113
Model 20 Jet (19941/2 THRU 1998)
113
Electric Start Models with Tiller Handle Start Button (Electronic Advance) Model 20/25 (19941/2 THRU 1997)
114
Electric Models Equipped with Remote Control (Electronic Advance) Model 20/25 (19941/2 THRU 1997)
115
Manual Start Models (Mechanical Advance) Model 20/25 (1998)
116
Electric Start Models with Tiller Handle Start Button (Mechanical Advance) Model 20/25 (1998)
117
Electric Models Equipped with Remote Control (Mechanical Advance) Model 20/25 (1998)
118
Manual Start Wiring Diagram (RED Stator) Model 20/25 (1999 and NEWER)(Work Model)
120
Electric Start Models with Tiller Handle Start Button
121
Electric Models Equipped with Remote Control (RED Stator) Model 20/25 (1999 and NEWER)
122
Optional Electrical Accessories Wiring Diagrams 2D-12
123
Commander Remote Control (Electric Start)
124
Commander 2000 Remote Control (Manual)
125
Commander 2000 Remote Control (Electric Start)
126
Commander 3000 Panel Mount Control
127
Fuel System
128
Carburetor (20/25/JET 20)
129
Carburetor (Seapro/Marathon 15/25 & Super 15)
131
Carburetor Adjustments
133
Low Speed Mixture Screw
133
Main Jet
133
High Altitude Jet Chart
134
Carburetor Float Adjustment
135
Fuel System
142
Carburetor Removal
145
Carburetor Installation
146
Fuel Pump
149
Removal and Disassembly
149
Cleaning and Inspection
149
Reassembly and Installation
149
Primer System
150
Symptoms of a Defective Primer System
150
Servicing Sight Bowl Fuel Filter
151
Fuel System
152
Controlling Emissions
153
Oxides of Nitrogen - Nox
153
Stoichiometric (14.7:1) Air/Fuel Ratio
153
Outboard Hydrocarbon Emissions Reductions
154
Stratified VS Homogenized Charge
155
Homogenized Charge
155
Emissions Information
156
Manufacturer's Responsibility
156
Stratified Charge
156
Dealer Responsibility
157
EPA Emission Regulations
157
Owner Responsibility
157
Decal Location
158
Emission Control Information
158
Section 4 - Powerhead
159
Specifications
160
Special Tools
161
Cylinder Block and Covers
163
Crankshaft, Pistons and Flywheel
165
Torque Sequence
167
Powerhead Removal
168
Powerhead Disassembly
170
Cylinder Block
170
Crankshaft
175
Powerhead Cleaning and Inspection
180
Cylinder Block and Crankcase Cover
180
Exhaust Manifold and Exhaust Cover
181
Cylinder Bore
181
Seals
185
Bearings
185
Connecting Rod
186
Pistons
189
Reed Block
190
Bleed System
191
Thermostat
192
Powerhead Reassembly
193
General Information
193
Crankshaft
193
Cylinder Block
204
Powerhead Installation
209
Break-In Procedure
210
Set-Up and Test-Run Procedures
210
Midsection
211
Clamp Bracket Assembly
212
Swivel Bracket Assembly
214
Drive Shaft Housing Assembly
216
Drive Shaft Housing Disassembly/Reassembly
217
Specifications
218
Quicksilver Lubricants and Service Aids
219
Special Tools
219
Gear Housing (Drive Shaft)
223
Gear Housing (Propeller Shaft)
225
General Service Recommendations
227
Draining and Inspecting Gear Lubricant
228
Gear Housing Removal
229
Disassembly
231
Bearing Carrier
231
Propeller Shaft
232
Water Pump
233
Shift Shaft
235
Drive Shaft and Pinion Gear
235
Upper Drive Shaft and Bearing/Seals
236
Lower Drive Shaft Bearing/Cup
237
Forward Gear Race
237
Cleaning and Inspection
238
Gear Housing/Bearing Carrier Castings
238
Ball Bearings
238
Needle Bearing
238
Cam Follower
239
Clutch
239
Propeller Shaft
239
Shift Shaft
240
Reverse and Forward Gear
240
Pinion Gear
242
Driveshaft
242
Bearing Carrier
243
Reassembly
243
Drive Shaft Bearing and Seals
243
Shift Shaft
245
Forward Gear Installation
246
Pinion and Driveshaft
248
Propeller Shaft
248
Bearing Carrier
250
Bearing Carrier/Propeller Shaft Installation 6A-34
251
Water Pump
252
Gear Housing Installation
253
Trim Tab Adjustment and Replacement
258
Filling Gear Housing with Lubricant
259
Specifications
260
Jet Pump Assembly (S/N 0G157845 & Below)
261
Jet Linkage (S/N 0G157845 & Below)
263
Jet Water Pump Components
264
Jet Pump Assembly (S/N 0G157846 & Up)
265
Jet Linkage (S/N 0G157846 & Up)
267
Engine Horsepower Selection
269
Selecting a Boat that Is Best Suited for Jet Power 6B-10
269
Locate Centerline of the Outboard
270
Outboard Mounting Height
270
Transom Height of the Boat
270
Water Testing
272
Checking for Cavitation
272
Shift Link Rod Adjustment
274
Checking Shift Link Rod Adjustment
274
Adjusting Shift Link Rod
274
Lubricating the Drive Shaft Bearing
275
Impeller Removal and Installation
276
Impeller Clearance Adjustment
279
Steering Pull Adjustment
279
Worn (Dull) Impeller
280
Liner Replacement
281
Jet Drive Removal and Installation
282
Removal
282
Installation
282
Water Pump Removal and Installation
283
Removal
283
Installation
283
Bearing Carrier Removal and Installation
284
Removal
284
Installation
284
Installing Drive Shaft Bearing
284
Single Bearing System (Small Diameter Bearing)
284
Single Bearing System (Large Diameter Bearing)
285
Installing Drive Shaft
286
Installing Upper Seal Housing
287
Single Bearing System
287
Controls
288
Throttle and Shift Linkage (Tiller Handle Shift)
289
Control Cables (Tiller Handle Shift)
291
Removal/Installation
291
Control Platform
291
Removal/Disassembly
291
Reassembly/Installation
294
Throttle Cam/Control Lever
297
Reassembly
297
Installation
299
Neutral Interlock Control Lever
300
Reassembly/Installation
300
Horizontal Shift Shaft
301
Removal
301
Installation
302
Tiller Handle Assembly
305
Control Cables
307
Removal
307
Tiller Handle Removal/Disassembly
309
Removal
309
Installation
311
Control Cables
313
Installation
313
Throttle and Shift Linkage (Side Shift)
316
Throttle Cables (Side Shift Models)
318
Removal/Installation
318
Throttle Cam/Control Lever
318
Removal
318
Throttle Cam/Control Lever
319
Reassembly
319
Installation
320
Neutral Interlock Control Lever
322
Reassembly/Installation
322
Horizontal Shift Shaft
323
Reassembly/Installation
323
Starter Assembly (Manual)
326
Rewind Starter Assembly
328
Removal
328
Section 8 - Manual Starter
328
Starter Rope Replacement
331
Disassembly
335
Cleaning and Inspection
336
Reassembly
336
4
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Mercury/Mariner 25 MARATHON Specifications
General
Brand
Mercury/Mariner
Model
25 MARATHON
Category
Outboard Motor
Language
English
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