EM 102 Overview

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EM 102 Overview

• Cooling and Exhaust Systems
• Lubrication
• Fuel and Air Induction Systems
• Ignition Systems
• Electrical and Starting Systems
• Power Trains
• Troubleshooting
• Emergency Repairs Afloat

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Cooling and Exhaust Systems

• Proper Cooling
• Cooling Systems
• Pumps
• Thermostat
• Maintaining a Cooling System
• Exhaust Systems

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Proper Cooling

• Temperature above
• 400 F may break down lubrication
• 500 F may burn valve seats and
  aluminum begins to loose its strength
• Water in water jacket removes 90 of heat
• Lubrication inside engine removes 10 of heat
• Must have air flow around outside of engine
• Overcooling may cause poor lubrication and alter
  engine clearances

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Cooling Systems

• Direct, or open
• Engine is cooled by sea water
• Disadvantage engine exposed to raw (salt) water
• Indirect, or closed
• Engine is cooled by coolant
• Mixture or antifreeze and clean (distilled) water
• Coolant is then cooled by seawater in heat
  exchange
• Disadvantage Requires heat exchange

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Direct vs Indirect Cooling
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Pumps

• Normally are belt driven off engine
• Three types Centrifugal, Gear and Impeller

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Thermostat

• Temperature-sensitive device used to maintain the
  correct operating temperature
• Ratings - 145 F and 195 F
• Fully open 2at 20 degrees over rating

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Maintaining a Cooling System

• Principal Operations
• Maintaining Circulating Pumps
• Preventing Corrosion
• Reducing the Formation of Scales
• Preventing Leaks
• Circulation Pumps
• Centrifugal
• Gear
• Impeller - Impeller and seal are repairable in
  field

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Maintaining -2

• Corrosion Prevention
• Sacrificial (zinc) anodes
• Quality anti-freeze and distilled water
• Reduce Scale Formation
• Keep seawater discharge below 145 F
• Distilled water and quality antifreeze
• Leak Prevention
• Raw water strainer
• Loose connection and hose deterioration

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Maintaining - 3

• Freezing Prevention
• During Winter Storage fill raw water system with
  antifreeze
• Belts
• Adjust to a firm tension
• One belt width of flex per foot of length
• New belts stretch
• Inspect for cracking and wear

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Exhaust Systems

• Exhaust gases are extremely hot and poisonous
• Are wet and dry Exhaust Systems
• Wet is preferred and safest
• Exhaust system must not ingest water
• Anti-siphon break (vacuum valve)

Exhaust Mixing Elbow
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Sail vs Power Exhaust Systems

• Sailboat engines are normally below water line
• Sailboats heal over (exhaust may be under water)
• Note Anti-siphon Valve in sailboat system

Typical Sailboat
Typical Inboard Powerboat
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Summary

• Cooling Systems
• Direct using raw (sea) water in engine
• Indirect using heat exchange
• Water Pumps Centrifugal, Gear and Impeller
• Maintenance
• Quality antifreeze, distilled water and zincs
• Belts adjust for firm tension and inspect for
  wear
• Exhaust Systems (gases are hot and poisonous)
• Dry used in automobiles
• Wet used in boats, preferred and safest
• Must not ingest water