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6A-20 - SEAWATER COOLING MODELS 90-823225--1 1096

Water Flow Diagrams

MCM Alpha

OVERBOARD

THERMOSTAT

COVER

THERMOSTAT

HOUSING

ENGINE

CIRCULATING

PUMP

ENGINE BLOCK

INTAKE MANIFOLD

AND CYLINDER HEAD

ASSY.

WATER INLET

(FROM STERN

DRIVE)

EXHAUST ELBOW

RESTRICTOR

EXHAUST

MANIFOLD

POWER

STEERING

FLUID

COOLER

22382

TO EXHAUST

MANIFOLDS

TO EXHAUST

ELBOW

FROM

ENGINE

TO ENGINE

CIRCULATING

PUMP

FROM WATER INLET

(VIA FLUID COOLER)

THERMOSTAT

LEGEND

COLD

WARM

22380

NOTE: Thermostat housing

check-balls will not be present

on later models.

(NOTE)

Important Information 1 a8
- Marine Engines1
- Replacement Parts3
- Table of Contents8
- Introduction9
- How to Use this Manual9
  - Page Numbering9
- How to Read Parts Manual10
- Directional References11
- Engine Rotation11
- Propeller Information12
- Water Testing New Engines12
- Boat and Engine Performance12
Important Information 1 B17
- Maintenance Schedules18
- Tune-Up Specifications24
- Tune-Up Specifications (Gen + Engines Only)27
  - Fluid Capacities28
- All Models29
  - 20-Hour Break-In Period29
  - After Break-In Period29
- Fuel, Oil, Fluid, and Coolant Specifications29
- Changing Oil and Filter32
- Maintaining Crankcase Oil Level32
  - Overfilled Engine Crankcase32
  - Checking Engine Oil Level/Filling32
- Maintaining Power Steering Pump Fluid Level33
  - With Engine Warm33
  - With Engine Cold33
- Filling and Bleeding Power Steering System 1B-1734
- Flushing Cooling System34
  - MCM Stern Drive35
  - MIE Inboard36
- Maintaining Closed Cooling Coolant Level34
- Maintaining Transmission Fluid Level37
- Lubrication38
- Audio Warning System42
  - Maintenance 1B-2542
- Cold Weather or Extended Storage42
Important Information 1 C60
- Precautions61
- Spark Plug Analysis62
  - Normal Condition62
  - Chipped Insulator62
  - Wet Fouling (Oil Deposits)62
  - Cold Fouling63
  - Overheating63
  - High Speed Glazing63
  - Scavenger Deposits63
  - Pre-Ignition Damage64
  - Reversed Coil Polarity64
  - Splashed Deposits64
  - Mechanical Damage64
- Used Spark Plug Analysis62
- Poor Boat Performance And/Or Poor Maneuverability65
- Improper Full Throttle Engine RPM66
  - RPM too High66
  - RPM too Low66
- Engine Cranks over but will Not Start or Starts Hard67
  - Important Information67
  - Testing Thunderbolt IV HEI System68
  - Testing Thunderbolt V Ignition System69
  - Fuel System Rich70
  - Fuel System Lean70
  - Miscellaneous70
- Charging System Inoperative71
  - Noisy Alternator71
- Engine will Not Crank over71
- Instrumentation Malfunction72
- Radio Noise72
- Poor Fuel Economy73
- Carburetor Malfunctions74
- Engine Runs Poorly at Idle75
- Engine Runs Poorly at High RPM76
- Engine Acceleration Is Poor77
- Troubleshooting with Vacuum Gauge77
- Engine Noise78
  - Important Information78
  - Valve Cover Area78
  - Cylinder Area79
  - Camshaft Area79
  - Crankshaft Area80
  - Miscellaneous81
- Oil Pressure82
  - Low Oil Pressure83
  - High Oil Pressure83
- Excessive Oil Consumption84
- Water in Engine85
  - Important Information85
  - Water on Top of Pistons85
  - Water in Crankcase Oil86
- Engine Overheats (Mechanical)86
- Engine Overheats (Cooling System)87
  - Insufficient Water Flow from Belt Driven Seawater Pickup Pump88
- Power Steering89
  - Poor, Erratic, or no Assist89
  - Noisy Pump90
  - Fluid Leaks90
- Troubleshooting Silent Choice Exhaust Silencer System91
Removal and Installation 293
- Tools/Lubricants/Adhesives/Sealants94
- Torque Specification94
- Removal95
  - Engine Removal95
- Installation96
  - Engine Installation/Alignment96
  - Engine Connections98
Removal and Installation 2104
- Removal106
  - Engine Removal106
- Installation108
  - Engine Installation/Alignment108
  - Engine Connections113
Removal and Installation 2121
- Tools/Lubricants/Adhesives/Sealants122
- Torque Specifications122
- Removal123
  - Engine Removal123
- Installation124
  - Engine Installation/Alignment124
  - Engine Connections127
Removal and Installation 2136
- Removal138
  - Engine Removal138
- Installation140
Removal and Installation 2155
- Lubricants/Sealants156
- Torque Specifications156
- Removal157
  - Engine Removal157
- Installation158
- Fuel Supply Connections162
- Attaching/Adjusting Reversed Attachment Morse Shift Cables170
Removal and Installation 2174
- Lubricants/Sealants175
- Torque Specifications175
- Removal176
  - Engine Removal176
- Installation177
Engine190
- Lubricants/Sealers/Adhesives196
- Engine Specifications197
  - L / 305 CID / 5.7L / 350 CID Engine199
  - Gen + Engine Specifications206
- General207
  - Engine Identification207
  - Cylinder Head Identification208
  - Engine Rotation208
  - Crankshaft208
  - Piston and Connecting Rods208
  - Camshaft and Drive209
  - Cylinder Head209
  - Valve Train209
  - Intake Manifold209
  - Lubrication System209
- Bearing Failures211
- Piston Failures212
  - Pre-Ignition212
  - Detonation213
- Engine Mounts214
- Intake Manifold216
  - Cleaning and Inspection216
  - Installation217
- Rocker Arm Cover216
  - Removal216
  - Installation216
- Rocker Arm/Push Rod219
  - Removal219
  - Cleaning and Inspection219
  - Installation219
- Valve Adjustment219
  - Engine Stopped219
  - Engine Running220
- Hydraulic Valve Lifters (Flat and Roller Lifter)221
  - Locating Noisy Lifters221
  - Removal222
  - Cleaning and Inspection222
  - Installation222
- Valve Stem Oil Seal/Valve Spring222
  - Removal - Head Installed222
  - Valve Assembly (Exploded View)224
  - Installation - Head Installed224
- Cylinder Head224
  - Removal224
  - Cleaning and Inspection225
  - Installation225
- Cylinder Head and Valve Conditioning226
  - Disassembly226
  - Cleaning226
  - Inspection226
  - Valve Guide Bore Repair227
  - Valve Springs - Checking Tension228
  - Rocker Arm Stud Replacement229
  - Valve Seat Repair229
  - Valve Grinding230
  - Reassembly230
    - Dipstick Specifications233
    - All Engines233
- Oil Pan234
  - Removal234
  - Installation234
- Oil Pump236
  - Removal236
  - Disassembly236
  - Cleaning and Inspection237
  - Reassembly237
  - Installation237
- Torsional Damper238
  - Removal238
  - Installation238
- Crankcase Front Cover239
  - Removal240
  - Cleaning and Inspection240
  - Installation240
- Crankcase Front Cover/Oil Seal239
  - Oil Seal Replacement (Without Removing Front Cover)239
- Flywheel240
  - Inspection241
  - Installation242
- Rear Main Oil Seal243
  - Removal243
  - Cleaning and Inspection243
  - Installation244
- Rear Main Oil Seal Retainer244
  - Removal244
  - Cleaning and Inspection244
Electrical Systems267
- Battery268
  - Battery Cable Recommendations268
- Identification268
- Lubricants/Sealants268
- Replacement Parts Warning268
- Torque Specifications268
- Direct Drive Starter Motor269
  - Specifications269
- Lubricants/Sealants269
- Positive Current Flow269
- Torque Specifications269
- Starting System Components270
- Starter Motor (Exploded View)271
- Periodic Inspection272
- Starter Motor Repair272
  - Removal272
  - Solenoid Switch272
  - Starter Motor Disassembly274
  - Cleaning and Inspection274
  - Armature Tests275
  - Field Coil Tests275
  - Loose Electrical Connections276
  - Turning the Commutator276
  - Reassembly276
  - Clearances277
  - Installation278
- (PG200, PG250 and PG260) Starter Motor279
  - Specifications279
  - Maintenance280
  - Testing280
  - Storage280
- Permanent Magnet Gear Reduction279
- Standard Starter Slave Solenoid281
  - Testing/Replacement281
- Starting System Components282
- Description283
- Positive Current Flow283
- And PG 250 Starter Motor (Exploded View)285
- And PG 250 Starter Motor Repair286
  - Removal286
  - Disassembly287
  - Cleaning and Inspection289
  - Armature Tests289
  - Armature Bearing (Commutator End)289
  - Gear Bearing290
  - Shaft Assembly Bearing290
  - Drive End Housing Bearing290
  - Brushes and Brush Holder291
  - Reassembly292
  - Installation294
- Periodic Inspection286
- Solenoid Switch286
- PG 260 Starter Motor295
  - Exploded View295
- Periodic Inspection296
- PG 260 Starter Motor Repair296
  - Removal296
  - Disassembly297
  - Cleaning and Inspection299
  - Armature Tests300
  - Brushes and Brush Holder300
  - Reassembly302
  - Clearances305
  - Installation305
- Solenoid Switch296
Electrical Systems309
- For Information and Procedures on Trouble309
- Notice309
- Shooting, Refer to Section 1C309
- Specifications311
- Repair315
- Distributor Repair318
- Distributor Installation321
  - Engine Not Disturbed321
  - Engine Disturbed321
- Thunderbolt IV Ignition Timing322
- Thunderbolt V Ignition System323
  - Identification323
- General Description324
- Thunderbolt V Spark Control Graph325
- Circuit Description326
- Ignition System Wiring Diagram327
- Timing and Idle Adjustment Procedures328
- Troubleshooting Thunderbolt V Ignition329
Electrical System335
- Mando 55 and 65 Amp Alternator Identification336
- Replacement Parts Warning336
- Specifications336
- Tools/Sealants336
- Torque Specifications336
- Description337
- Precautions337
- Periodic Maintenance338
- System Components338
- Drive Belt Tension Adjustment339
  - V-Belt339
  - Serpentine Belt339
- Troubleshooting Tests (Alternator on Engine)340
- Alternator Repair346
- Installation355
- Battery Isolators356
  - Dual Battery Charging Systems Using a Battery Isolator356
- Battery Isolator357
Electrical System361
- Identification362
- Special Information362
  - Lighting Options362
    - Commodore and International Series362
    - QSI Series363
- Gauges363
- Senders366
- Switches370
- Audio Warning System372
Electrical Systems394
- Thunderbolt IV395
- EFI Engine Harness410
- Audio Warning System425
- Battery Meter Gauge425
- Cruiselog425
- Fuel Gauge and Sender425
- Clock426
- Oil Pressure Gauge426
- Water Temperature Gauge426
Fuel System428
- Identification429
- Replacement Parts Warning429
- Specifications429
- Tools / Lubricants / Sealants429
- Torque Specifications429
  - Fuel Supply Connections429
- Fuel Delivery System430
  - Recommendations430
- Precautions430
- Fuel System Components431
- Water Separating Fuel Filter435
  - Replacement436
- Sight Tube436
  - Inspection436
- Mechanical Fuel Pump437
  - Replacement437
- Testing Mechanical Fuel Pump437
Fuel System439
- Mercarb 2 BBL Carburetor440
- Exploded View441
- Identification443
- Important Service Information443
- Description444
- Maintenance445
- Precautions445
- Adjustments447
- Repair450
Fuel Systems468
- Carburetor Adjustment Specifications470
- Carburetor Specifications470
- Description471
- Maintenance471
  - Flame Arrestor471
  - Fuel Filter472
- Precautions471
- Adjustments473
- Repair478
Fuel Systems498
- Identification499
- Replacement Parts Warning499
- Tools499
  - Carburetor Adjustment Specifications501
- Torque Specifications499
- Description502
- Precautions502
- Important Service Information503
- Maintenance505
  - Flame Arrestor505
  - Fuel Filter506
- Adjustments507
- Idle Speed and Mixture Adjustments510
  - Thunderbolt IV Equipped Engines510
  - Thunderbolt V Equipped Engines512
- Repair513
Fuel Systems539
- General Information542
- Electronic Control Module (ECM) and Sensors551
- ECM Connector and Symptom Charts568
- Diagnostic Circuit Check592
Fuel Systems728
- Identification729
- Replacement Parts Warning729
- Special Tools729
- Torque Specifications729
- Carburetor Adjustment Specifications730
- Carburetor Specifications730
- Engine Specifications730
- Description731
- Special Notes731
- Precautions733
- Maintenance734
- Troubleshooting735
  - Checking Ported Vacuum Switch735
    - And Carburetor Vacuum Circuit for Correct Operation735
- Service Procedures736
- Emissions Testing742
- Test Equipment742
Cooling System745
- MCM 350 CID / 5.7L746
- Seawater Inlet Recommendations747
- Seawater Pickups748
  - Thru-Hull Mounted748
  - Transom Mounted748
- Sea Strainer (Quicksilver)749
  - Removal749
  - Installation750
- Stern Drive Unit Seawater Pickup Pump Output Test751
- Stern Drive Unit Seawater Pickup Pump Repairs752
- Water Circulating Pump Replacement752
- Flushing Seawater Cooling System753
- Thermostat754
- Draining Seawater Cooling System757
- Auxiliary Hot Water Heater Installation763
- Water Flow Diagrams765
Cooling System774
- 305/350 CID / 5.0L/5.7L775
- Water Flow Diagrams776
  - Engines with Coolant Flow Thru Exhaust776
  - Engines with Raw Water Flow Thru Exhaust Manifolds777
- Description778
- Seawater Pickup Pump (if Equipped)778
- Pressure Cap Maintenance791
- Heat Exchanger Repair792
- Testing Closed Cooling System792
- Thermostat795
- Changing Coolant800
- Cleaning System801
- Filling Closed Cooling Section806
Exhaust System824
- Exhaust System Requirements825
- Exhaust Tube Requirements827
Exhaust System845
- Lubricants/Sealants/Adhesives846
  - Shutter Replacement846
  - Component Replacement847
- Torque Specifications846
- Below Swim Platform Exhaust Pipe Kit848
  - Modifying Swim Platform Exhaust Pipe, if Required849
- Thru-Transom Exhaust848
  - Shutter Replacement848
  - Component Replacement848
- Silent Choice Exhaust System849
- Exhaust Muffler Kit852
Drives857
- Velvet Drive In-Line (71C and 72C) Specifications858
- Important Information860
- Checking Transmission Fluid Level861
- Shift Cable Adjustment861
- Changing Transmission Fluid862
  - Draining Transmission862
  - Filling Transmission863
- Removal and Installation864
- Pump Indexing865
- Pressure Test866
- Shift Lever Installation866
- Transmission Repair866
Drives870
- Transmission Fluid Capacities872
- Transmission Fluid Specification872
- Transmission Output Shaft Rolling Torque872
- Transmission Pressure Specifications872
- Important Information873
- Checking Transmission Fluid Level874
- Shift Cable Adjustment874
- Changing Transmission Fluid875
  - Draining Transmission875
  - Filling Transmission876
- Removal and Installation877
- Pump Indexing878
- Pressure Test879
- Shift Lever Installation879
- Transmission Repair879
  - V-Drive879
Drives883
- Specifications885
- General886
- Shift Cable Installation and Adjustment886
- Checking Transmission Fluid Level891
- Draining Transmission892
- Filling Transmission892
- Transmission Removal893
- Transmission Installation894
- Transmission Repair895
- Functional Test929
Drives933
- Tools/Lubricants/Sealants934
- Torque Specifications934
- (MCM Stern Drive Models)935
  - Repair937
  - Replacement Drive Shafts937
- Repair (MCM Stern Drive Models)935
- Installation938
- Bearing Support Repair (MCM Stern Drive Models)939
- Propeller Shaft (MIE Inboard Models)942
Power Steering948
- (Exploded View)950
- Power Steering Pump and Components950
- Serpentine Belt Routing951
- Important Service Information952
  - Pump Pulley Replacement952
- Belt Adjustment953
  - V-Belt953
  - Serpentine Belt Adjustment953
- Checking Pump Fluid Level953
- Filling and Air Bleeding System953
- Testing and Repair953
- Pump Assembly954
- Hydraulic Hoses and Fluid Cooler955
  - Valve)955
  - Low Pressure Hose (Control Valve-To-Cooler)958
- Mounting Bracket955
- Priority Valve Kit (79691A1) Information960

Brand	Mercury
Model	305 CID
Category	Engine
Language	English

Mercury 305 CID User Manual

Table of Contents

Questions and Answers:

Mercury 305 CID Specifications

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