Mercury BRAVO

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CORROSION PROTECTION - ALL MODELS

SERVICE MANUAL NUMBER 28

90-863160 MAY 2000 Page 7A-13

Wiring Diagrams

MerCathode Monitor

74251

a-Instrument Panel Ground

b-Screw, Nut and Sleeve

c-Electrode

d-20 Amp Fuse

e-Controller

Main Page

Engine Mechanical Components4
Replacement Parts4
Service Manual Outline5
Table of Contents6
Power Trim10
Steering Systems11
General Information13
How to Use this Manual14
Page Numbering14
How to Read a Parts Manual15
Directional References16
Propeller Rotation16
Sterndrive Unit 10-Hour Break-In Period (New or with Replacement Gears)17
Serial Number Locations and Engine Designation Decal17
Transom Assembly Serial Number Location17
Maintenance19
Lubricants/Sealants/Adhesives20
Maintenance Schedules21
Maintenance Intervals21
Gas Sterndrive21
Specifications23
Propeller Shaft24
Steering System24
Tie Bar Pivot Points25
Checking and Adding Sterndrive Oil26
Inspection27
Changing Sterndrive Oil28
General Maintenance30
Power Package Layup31
Power Package Recommissioning32
Troubleshooting33
Sterndrive Unit Troubleshooting34
Sterndrive Unit will Not Slide into Bell Housing34
Drive Unit Does Not Shift into Gear; Remote Control Shift Handle Moves34
Drive Unit Does Not Shift into Gear; Remote Control Shift Handle Does Not Move35
Drive Unit Shifts Hard35
Drive Unit in Gear, will Not Shift out of Gear35
Gear Housing Noise36
Drive Shaft Housing Noise36
Power Shift Troubleshooting39
System Does Not React39
System Binds39
Performance Troubleshooting40
Low WOT Engine RPM40
High WOT Engine RPM40
Propeller Ventilating/Cavitating40
Poor Boat Performance And/Or Poor Maneuverability-Bow too Low41
Poor Boat Performance And/Or Poor Maneuverability-Bow too High41
Power Steering Troubleshooting42
Hard Steering - Helm and Cable42
Hard Steering (Engine Running) - Power Steering System42
Power Steering System External Fluid Leaks42
Compact Hydraulic Steering Troubleshooting43
Helm Becomes Jammed During Filling43
Steering Hard to Turn43
Helm Unit Bumpy - Requires too Many Turns43
Power Trim Electrical System Troubleshooting44
Power Trim Pump Motor will Not Run in the OUT/UP or IN/DOWN Direction44
Solenoids Do Not Click44
Both Solenoids Click45
Power Trim Pump Motor Runs in the OUT/UP Direction, but Not in the IN/DOWN Direction45
In/Down Solenoid Does Not Click45
In/Down Solenoid Clicks46
Power Trim Pump Motor Runs in the IN/DOWN Direction, but Not in the OUT/UP Direction-Both Trim and Trailer Switches Inoperative46
Out/Up Solenoid Does Not Click46
Out/Up Solenoid Clicks46
Trim Control OUT/UP Trim Switch Inoperative47
Trim Control Trailer Switch Inoperative47
Trim Out/Up Switch Functions47
Trim System Functions While Unattended47
Power Trim System Wiring Diagram48
Power Trim Hydraulic System Troubleshooting49
Drive Unit Cannot be Trimmed OUT/UP or Trims Slowly or with Jerky Movements49
Drive Unit will Not Stay in Trimmed OUT/UP Position49
Sterndrive Unit Trails OUT/UP on Deceleration or When Shifting into Reverse49
Oil Foams out of Pump Fill/Vent Screw50
Sterndrive Unit Cannot be Lowered from up Position or Lowers with Jerky Movements50
Sterndrive Unit will Not Stay in Full up Position for Extended Periods50
Sterndrive will Not Stay in the Trimmed OUT/UP Position When Underway51
Sterndrive Unit Trails out / up on Deceleration or When Shifting into Reverse51
Unit Thumps When Shifting51
Oil Foams out of Pump Fill / Vent Screw51
Trim Motor Runs but Does Not Pump Oil52
Trim Pump Runs Slowly in both Directions52
Trim Pump Runs Slowly with a Laboring Sound52
Power Trim Hydraulic Schematic53
Auto Trim II Electrical System Troubleshooting54
Pump Motor will Not Run up or down in Either Manual or Auto Mode54
Pump Motor will Not Stop Running down in Auto Mode56
Pump Motor will Not Run up or down in Auto Mode56
Trim System Completely Inoperative in Manual Mode57
Pump Motor will Run UP, but Not down in both Manual and Auto Modes57
Pump Motor Runs DOWN, but Not up in both the Manual and Auto Modes57
Pump Motor will Run DOWN, but Not up in Auto Mode58
Pump Motor will Run UP, but Not down in Auto Mode58
Trim DOWN/IN Switch Inoperative in Manual Trim Control58
Trim UP/OUT Switch Inoperative in Manual Trim Control59
Trailer Switch in Manual, Trim Control Inoperative59
Boat Is on Plane Well before Drive Unit Begins to Trim out59
Boat Is Not on Plane before Drive Unit Begins to Trim out59
Auto Trim II System Wiring Diagram60
Corrosion Protection Troubleshooting61
Corrosion on Underwater Parts, Without Mercathode or Impressed Current Protection61
Corrosion on Underwater Parts, with Mercathode or Impressed Current Protection62
Corrosion on Underwater Parts with Mercathode or Impressed Current Protection64
Testing Procedure for Corrosion Protection65
Corrosion Symptoms65
Mercathode Controller Diagram66
Removal, Installation and Adjustments - All Models69
Torque Specifications70
Lubricants/Sealants/Adhesives Table70
Tools70
Transom Thickness and Surface71
Bravo Three Notice: Trim-In Limit Insert72
Sterndrive Unit Removal74
Transom Assembly Removal76
Transom Assembly Installation80
Sterndrive Unit Installation90
Shift Cable Installation and Adjustment97
Troubleshooting Shift Problems101
Proper Cable Bend101
Improper Cable Bend101
Sterndrive Unit. Drive Shaft Housing103
Drive Shaft Housing Specifications104
Drive Shaft Housing Exploded View106
Exploded Parts View (Clutch)108
Exploded Parts View (Shifter)109
Standard Bravo U-Joint Assembly110
Bravo X, XZ, XR and Diesel Bravo U-Joint Assembly111
Drive Shaft Housing and Gear Case Separation112
Drive Unit Gear Ratio Identification112
Separate Housings116
Drive Shaft Housing Disassembly119
Shifter Repair124
Shifter Inspection127
Shifter Reassembly128
U-Joint and Pinion Gear Inspection132
U-Joint and Pinion Gear Disassembly132
U-Joint and Pinion Gear Reassembly136
Gear Disassembly, Inspection and Reassembly144
Gear Disassembly144
Gear Inspection146
Gear Reassembly146
Drive Shaft Housing and Top Cover - Bearings and Bearing Sleeves Inspection149
Bearing Sleeve Removal (Top Cover)149
Bearing Sleeve Removal (Drive Shaft Housing)150
Roller Bearing Removal151
Steel Bearing Adaptor Removal153
Steel Bearing Adaptor Installation154
Bearing Sleeve Installation155
Roller Bearing Installation156
Drive Shaft Housing Reassembly157
Torque Conversion Chart for U-Joint Retainer Nut Tool161
Torquing Bravo U-Joint Bearing Retainer Nut161
Install Gear Housing to Drive Shaft Housing168
Bravo One Gear Housing173
Bravo One Gear Housing Specifications174
Bravo One Gear Housing Exploded View176
Drive Shaft Components View176
Bravo One and Diesel Bravo One X Propeller Shaft Components View178
Bravo XZ and Bravo XR Propeller Shaft Components View180
Pre-Disassembly Inspection182
Drive Shaft Housing and Gear Housing Separation183
Gear Housing Disassembly185
Drive Shaft and Pinion Bearing Inspection and Cleaning191
Drive Shaft Disassembly191
Pinion Bearing Removal192
Pinion Bearing Installation193
Drive Shaft Reassembly194
Bearing Carrier Inspection195
Bearing Carrier Disassembly195
Bearing Carrier Reassembly196
Propeller Shaft Inspection197
Propeller Shaft Bearing Removal197
Propeller Shaft Bearing Installation198
Driven Gear Bearing Inspection198
Driven Gear Bearing Removal199
Driven Gear Bearing Installation199
Driven Gear Bearing Cup Removal and Inspection200
Driven Gear Bearing Cup Installation200
Speedometer Water Passage201
Pickup Inspection and Cleaning201
Water Passage Seal Replacement202
Gear Housing Reassembly and Shimming203
Bravo XZ and XR Heavy Duty Propeller Shaft217
Gear Housing Disassembly/Reassembly217
Installing Bearing Carrier217
Installing Propeller Hub Assembly219
Bravo Two Gear Housing221
Bravo Two Gear Housing Specifications222
Bravo Two Gear Housing - Tools Needed223
Bravo Two Gear Housing Exploded View224
Drive Shaft and Propeller Shaft Components View224
Bravo Two Gear Housing Pre-Disassembly Inspection226
Separation of Drive Shaft Housing and Gear Housing227
Gear Housing Disassembly (Bravo Two)228
Drive Shaft and Pinion Bearing Inspection and Cleaning (Bravo Two)234
Drive Shaft Disassembly (Bravo Two)235
Pinion Bearing Removal (Bravo Two)236
Pinion Bearing Installation (Bravo Two)237
Drive Shaft Reassembly (Bravo Two)238
Bearing Carrier Inspection (Bravo Two)239
Bearing Carrier Disassembly (Bravo Two)240
Bearing Carrier Reassembly (Bravo Two)241
Propeller Shaft Inspection (Bravo Two)243
Propeller Shaft Bearing Removal (Bravo Two)244
Propeller Shaft Bearing Installation (Bravo Two)244
Driven Gear Bearing Inspection (Bravo Two)245
Driven Gear Bearing Removal (Bravo Two)245
Driven Gear Bearing Installation (Bravo Two)246
Driven Gear Bearing Cup Removal and Inspection (Bravo Two)246
Driven Gear Bearing Cup Installation (Bravo Two)247
Speedometer Water Passage (Bravo Two)247
Pickup Inspection and Cleaning (Bravo Two)247
Water Passage Seal Replacement (Bravo Two)248
Gear Housing Reassembly and Shimming (Bravo Two)249
Bravo Three Gear Housing263
Bravo Three Gear Housing Specifications264
Torque Conversion Chart for Bearing Carrier265
Torque Conversion Chart for Bearing Retainer Nut265
Torquing Outer Prop Shaft Bearing Retainer and Bearing Carrier266
Lubricants/Sealants/Adhesives (Bravo Three)266
Bravo Three Gear Housing - Tools Needed267
Bravo Three Gear Housing Exploded View268
Drive Shaft and Propeller Shaft Components View (Bravo Three)268
Pre-Disassembly Inspection (Bravo Three)270
Gear Housing Disassembly (Bravo Three)271
Driveshaft and Pinion Bearing Inspection and Cleaning (Bravo Three)278
Drive Shaft Disassembly (Bravo Three)279
Drive Shaft Reassembly (Bravo Three)279
Pinion Bearing Removal (Bravo Three)280
Pinion Bearing Installation (Bravo Three)281
Propeller Shaft Inspection (Bravo Three)281
Propeller Shaft Disassembly (Bravo Three)282
Propeller Shaft Spline Lash Check (Bravo Three)283
Outer Propeller Shaft Servicing285
Front Driven Gear and Bearing Inspection (Bravo Three)286
Bearing Removal (Bravo Three)286
Bearing Installation (Bravo Three)286
Bearing Cup Removal (Bravo Three)287
Bearing Cup Installation (Bravo Three)287
Bearing Carrier Seal and Bearing Inspection288
Bearing Carrier Seal and Bearing Removal288
Bearing Carrier Seal and Bearing Installation288
Speedometer Water Passage (Bravo Three)289
Inspection and Cleaning (Bravo Three)289
Seal Removal (Bravo Three)290
Seal Installation (Bravo Three)290
Gear Housing Reassembly and Shimming (Bravo Three)291
Checking Backlash (Bravo Three)298
Installing Gear Housing on Drive Shaft Housing304
Propeller Installation305
Transom Assembly: Service Procedures Requiring Minor Disassembly307
Bravo Transom Assembly Specifications308
Bravo Transom Assembly - Tools Needed308
Bravo Transom Assembly Exploded Views310
Inner Transom Plate Components310
Bell Housing Components311
Gimbal Ring Components312
Gimbal Housing Components View314
Bravo Transom Assembly: Special Information316
Trim Limit Switch316
Trim Position Sender Removal316
Trim Position Sender Installation318
Trim Position Sender Adjustment322
Trim Limit Switch Adjustment322
High Performance Transom Assembly - Without Electrical Trim Sender and Trim Limit Switch324
Gimbal Bearing Inspection325
Gimbal Bearing Removal325
Gimbal Bearing Installation326
Shift Cable Removal328
Shift Cable Installation329
Exhaust Bellows Removal333
Exhaust Bellows Cleaning and Inspection333
Exhaust Bellows Installation334
Exhaust Tube Removal336
Exhaust Tube Cleaning and Inspection336
Exhaust Tube Installation337
Water Hose and Water Fitting Removal338
Water Hose and Water Fitting Installation339
Crimp Clamp Tool341
Service Procedures Requiring Major Disassembly343
Bravo Transom Assembly: Specifications344
Service Procedures Requiring Major Disassembly: Tools Needed344
Bravo Transom Assembly: Exploded Views346
Inner Transom Plate Components View346
Bell Housing Components View347
Gimbal Ring Components View348
Gimbal Housing Components350
Bell Housing Removal352
Access Plug Kit Installation356
Gimbal Ring, Swivel Shaft and Steering Lever Removal358
Gimbal Ring Servicing362
Gimbal Ring Identification362
Bushings Installation363
Gimbal Housing Servicing368
U-Joint Bellows Replacement368
Shift Cable Bellows Replacement371
Exhaust Bellows Replacement374
Speedometer Hose Replacement376
Gear Lube Monitor System Components377
Monitor to through Bulkhead Fitting Hose377
Through Bulkhead to Bell Housing Gear Lube Monitor Hose377
Bell Housing to Drive Shaft Housing Check Valves378
Gear Lube Monitor System Reassembly379
Trim Position Sender and Trim Limit Switch Wire Replacement380
Gimbal Ring/Swivel Shaft and Steering Lever Installation381
Bell Housing Installation387
Standard Transom Assembly387
High Performance Transom Assembly388
Standard and High Performance Transom Assemblies389
To Install the Shift Cable393
Bravo Access Plug Drilling Template397
Power Trim: Oildyne Trim Pump401
Trim Pump Specifications402
Oildyne Trim Pump: Tools Needed402
Trim Pump Exploded View403
Maintaining Power Trim Pump Oil Level404
Air Bleeding Power Trim System405
Bleeding OUT/UP Trim Circuit405
Bleeding IN/DOWN Trim Circuit405
Testing Power Trim Pump406
Test Gauge406
Internal Restriction Test407
OUT/UP Pressure Test408
IN/DOWN Pressure Test410
Trim Pump Hydraulic System411
Trim Cylinder Internal Leak Test412
Trim Cylinder Shock Piston Test415
Motor and Electrical Bench Tests416
Trim Pump Motor Test (in Boat)416
Trim Pump Motor Test (out of Boat)418
Solenoid Test (Pump in Boat)419
Solenoid Test (Pump out of Boat)420
110 Amp Fuse Test (Pump in Boat)422
110 Amp Fuse Test (Pump out of Boat)423
20 Amp Fuse Test423
Trim Pump Removal424
Hydraulic Repair - Disassembly425
Filter Replacement427
UP Pressure Relief Valve Replacement428
DOWN Pressure Relief Valve Replacement429
Thermal Relief Valve Replacement430
Pump Replacement430
Adapter Replacement431
Adapter Repair433
Internal O-Ring and Poppet Valve Replacement433
Pump Shaft Oil Seal Replacement437
Motor Repair - Disassembly439
Armature Tests442
Continuity Test442
Test for Shorts443
Cleaning Commutator443
Field Tests443
Test for Open Circuit443
Test for Short in Field444
Thermal Switch Continuity Test445
Brush Replacement446
Motor Reassembly449
Trim Pump Installation455
Trim Pump Wiring Diagrams456
Model with Three-Button Trim/Trailer Panel456
Model with Trim in Handle and Trailer Switch Separate457
Power Trim: Trim Cylinders459
Trim Cylinders Specifications460
Trim Cylinders: Tools Needed460
Trim Cylinder Exploded Views461
Bravo Trim Cylinders View461
Bravo Trim System Components View462
Power Trim Hydraulic Schematic Diagram463
Trim Cylinders: Special Information464
Bravo Three Notice - Trim-In Limit Insert464
Trim Cylinder Repair465
Trim Cylinder Removal465
Trim Cylinder Disassembly467
Trim Cylinder Reassembly472
Trim Cylinder Installation479
Dual Power Trim System481
Dual Power Trim System: Important Information482
Testing Dual Power Trim System482
Relay Test482
Diode Module Test483
Trailer Switch Test484
Starboard Trim Switch Test484
Port Trim Switch Test484
Dual Power Trim System Component Repair485
Relay Replacement485
Diode Module Replacement487
Trim Control Panel Switch(Es) Replacement488
Trim Control Panel Switch(Es) Removal488
Trim Control Panel Switch(Es) Installation489
Wiring Diagrams490
Dual Trim Harnesses Wiring Diagram490
Electrical Box Wiring Diagram491
Auto Trim II493
Auto Trim II System Description494
Auto Trim II Operation494
Auto Mode Operation495
Boat Running above Planing Speed - Diagram495
Boat Running below Planing Speed - Diagram495
“Manual” Mode Operation496
Raising Sterndrive Unit to Trailer Position496
Trimming Sterndrive Unit out (Bow Up)497
Trimming Sterndrive Unit in (Bow Down)497
Electrical System Overload Protection498
Auto Trim Limit Adjustment498
Boat Properly Trimmed - Diagram498
Boat too High/Too Low - Diagrams498
Adjusting Sterndrive Unit Trim Angle499
Dry Dock Procedure499
On-Water Procedure500
Control Module Adjustment501
Trim Position Indicator Adjustment502
Auto Trim II Wiring Diagram503
Power Steering505
Power Steering Specifications506
Power Steering: Tools Needed506
Power Steering Description507
Control Valve507
Power Steering System Diagram - Right Turn508
Power Steering System Diagram - Left Turn509
Power Steering System Diagram - Neutral510
Steering Helm and Cable511
Locking Sleeve511
Steering Cable Specifications512
Filling and Air Bleeding Power Steering System513
Checking Fluid Level513
Filling and Bleeding the Power Steering System514
Power Steering Assembly Removal515
Power Steering Assembly Installation516
Power Steering System Pressure Test519
Pump Pressure Test521
Power Steering Pump Removal523
Flow Control Valve Servicing524
To Replace the Pump Shaft Oil Seal525
Power Steering Pump Disassembly527
Power Steering Pump Cleaning and Inspection530
Power Steering Pump Reassembly530
Power Steering Pump Installation536
Multiple Sterndrive Steering Tie Bar Arrangements537
Determining Tie Bar Length538
Tie Bar Selection539
Tie Bar Installation539
Dual Installations with Steering Cable Attached to Starboard Power Package539
Dual Installations with Steering Cable Attached to Port Power Package540
Steering Systems543
Compact Hydraulic Steering543
Important Information about Thru-Transom Exhaust544
Compact Hydraulic Steering Torque Specifications544
Installing the Steering Cylinder546
Filling and Purging the System548
Twin Station And/Or Twin Cylinder548
Single Station with Single Cylinder - Filling549
Single Station with Single Cylinder - Purging550
Connecting the Clevis552
Hydraulic Fluid Level553
Setting Fluid Level553
Maintaining Fluid Level553
System Check553
Corrosion Protection555
Corrosion Protection - Tools Needed556
Continuity Circuit556
Trim Cylinder Anodes559
Anodic Plate560
Bravo One Sterndrive Units560
Bravo Two Sterndrive Units562
Bravo Three Sterndrive Units562
Integral Mercathode System563
Removing Electrode Assembly563
Installing Electrode Assembly564
Connect Electrical Leads to Controller Assembly566
Mercathode Monitor Wiring Diagram567
Mercathode Controller Wiring Diagram568
Quicksilver Isolator569
Corrosion Protection Testing and Troubleshooting569
Digital Multimeter and Mercathode Reference Tester 76675A1 View570
Electrode Mounted on Bottom of Transom Assembly571
Electrodes Mounted on Boat Transom571
Test Equipment Set-Up572
Low Readings573
High Reading575
Normal Reading but Corrosion Is Evident575
Corrosion on the Entire Sterndrive Unit575
Corrosion Problem Developed after Refinishing the Drive Unit, Paint Blistering on Drive Unit575
Trim Cylinder Corroding576
Only One or Two Components Corroding576
Corrosion in the Exhaust Outlet Area576
Aluminium Corroding in Lubricated Areas576
Stainless Steel Components Corroding577
Stainless Steel Propeller Corroding577
Paint Blistering - the Metal under the Blistered Paint Is Not Pitted577
Accessories579
Accessories Specifications580
Power Shift (P/N 38638A4)580
Attaching Output Shift Cable to Sterndrive Unit581
Cable Replacement581
General Information581
Determining Input Cable Length582
Determining Output Cable Length582
If Relocating the Power Shift Cylinder582
Checking Vacuum Drop-Off583
Power Shift Cylinder Repair584
Power Shift Cylinder Removal584
Power Shift Cylinder Disassembly584
Power Shift Cylinder Reassembly587
Shift Cable Replacement and Adjustment592
Shift Cable Barrel Adjustment592
Installing Input Cable593
Installing Output Cable594
Attach Dust Cover594
Mounting Power Shift Cylinder595
Connecting Vacuum Hose to Engine595

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