Maintaining your Marine Diesel Engine and System

Reliable and Robust

Simple, regular maintenance is the easiest, quickest and cheapest way to avoid problems and accelerated engine wear. Most expensive repairs start from a lack of basic maintenance or ignoring small warnings. The work is not difficult - it just needs to be done.

The purpose is to make the whole diesel system reliable and robust – so that we can enjoy our boat for all the reasons we bought her.

Trust yourself. Do the work regularly and be methodical.

  1. Know your boat. Take full responsibility. Don’t assume that because something was installed by a previous owner or the boatbuilder that it’s correct or correctly installed. Some boatbuilders, as well as owners, have been known to cut corners.
  2. Can you afford cheap? Quality components rarely fail suddenly (unless the boat hits something). Using quality parts and supplies, and doing the job right the first time,  usually saves money in the long run as well as aggravation. Pay now or pay later.
  3. Cultivate vigilance as a habit. Take heed of a warning that something is not right – a new sound, less water in the exhaust, a nut or washer under the engine. A keen eye goes a long way to being able to spot potential problems before they become trouble.
  4. The “diesel engine” is a system. All the parts need to work together and to be in balance. Problems arise when they’re not. Neglecting any one area (perhaps because it’s too hard to reach) may well have effects that show up somewhere else.

 

Engine Maintenance Log
Engine Maintenance Log is an important to preventing trouble

Value of the Maintenance Log

One of the most important, and easiest, ways to ensure the health and longevity of all mechanical equipment on a boat is keep a Maintenance Log. The more comprehensive and detailed, the more useful the logbook becomes over time:

A Maintenance Log has four main functions:

  1. early warning of potential problems. Most problems develop slowly and are often simple to correct if caught early
  2. time and details of any changes in performance
  3. recording details of work done and equipment serviced
  4. system history – what was done, when, how and by whom

A plain A4 or Letter-sized notebook makes a practical Log. Divide each double page spread into four columns:

• date/time – especially useful when monitoring a developing problem over time
• item – which component (e. g. oil filter, alternator, transmission, propeller etc.)
• notes – write down the details
• follow-up – what further action needs to be taken?

Inspecting a raw water pump impeller
Six faults to look for when inspecting a rubber raw water pump impeller
Engine dipstick is a valuable diagnostic tool
The engine dipstick is a valuable diagnostic tool. Five simple checks can signal at lot about the internal health of the engine

Schedule of Marine Diesel Maintenance Tasks

(always check the Engine Manual for specific service intervals)

Download a free illusatrated Task List

Daily
Weekly
Monthly
3 Months
Seasonal
6 Months
Yearly
1 – 2 Years

Saildrives

Marine Diesel Maintenance Tasks
by Section

 

Engine Essentials
Diesel Fuel
Lubrication
Raw Water Cooling
Coolant/Antifreeze
Breathing - Air Intake & Exhaust
Electrical
Drive Train

Daily

Engine Essentials

  • visual engine room inspection
  • check engine oil level
  • check belt tension
  • check coolant/antifreeze & top up as needed

Lubrication

  • check engine oil level

Electrical

  • keep battery fully charged or trickle charge
Daily engine room inspection

Engine Essentials

  • visual engine room inspection
  • check engine oil level
  • check belt tension
  • check coolant/antifreeze & top up as needed
  • check transmission fluid level
  • inspect belts – alternator, coolant & raw water pump
  • inspect pulleys (sheaves)
  • check alignment of belts & pulleys
  • adjust pulley alignment
  • tighten alternator and water pump belts

Weekly

Engine Essentials
check transmission fluid
inspect hoses and hose clamps
fit & inspect anti-chafe protection
inspect wires & terminals inspect belt(s)

Lubrication
dipstick diagnostics – engine oil
check transmission fluid level
dipstick diagnostics – transmission

Coolant/Antifreeze
check coolant level in header tank or overflow bottle
inspect condition of coolant

Electrical
check battery open circuit voltage with multimeter

Drive Train
scrape the propeller, strut & shaft (as needed)

How small is small? comparison of common micron sizes and diesel

Diesel Fuel

  • inspect fuel deck fill
  • add biocide to the fuel tank(s)
  • change the primary fuel filter (use 10 micron filter)
  • change secondary fuel filter (use 2 micron filter)
  • bleed the fuel system
  • check diesel tank(s) for contamination
  • inspect injection pump and injectors

Monthly

Engine Essentials

  • inspect pulleys (sheaves)
  • inspect alignment of belts & pulleys
  • adjust pulley alignment (as needed)
  • tighten alternator & water pump belts (as needed)
  • inspect & repair sound insulation

Diesel Fuel

  • inspect injection pump & injectors

Electrical

  • keep battery terminal connections tight
  • clean battery tops and terminals
  • check electrolyte levels in unsealed wet-cell batteries
  • check specific gravity of cells in wet-cell battery
  • add distilled water to wet-cell battery

Raw Water Cooling

  • flush syphon break in fresh water

Breathing

  • check and clean air filter 100 hours

Lubrication

  • change engine oil & filter
Diesel injection pump with explanatory labels

Lubrication

  • check engine oil level
  • dipstick diagnostics - engine oil
  • check transmission fluid level
  • dipstick diagnostics - transmission fluid
  • change the engine oil & filter
  • change the transmission fluid (engine oil)
  • grease control cable ends and engine mount threads

 

Raw Water Cooling

  • clean thruhull of anti-foul paint and marine growth
  • check emergency plug tie to every seacock
  • check seacock(s) open/close smoothly
  • inspect raw water strainer
  • inspect raw water pump & impeller
  • check and change heat exchanger anode(s)
  • flush and clean the syphon break

Coolant/Antifreeze

  • check coolant/antifreeze level in header tank or overflow bottle
  • inspect condition of coolant
  • drain and replace worn-out coolant/antifreeze (2 years)

3 Months

Diesel Fuel

  • inspect fuel deck fill add biocide to the fuel tank(s) (on filling tank)

Breathing

  • ensure adequate air flow through engine room

Drive Train

  • check coupling transmission/prop shaft
  • inspect stern gland (stuffing box)
5 types of diesel engine air intakes and filters

Breathing – Air Intake & Exhaust

  • clean the air filter
  • check adequate air flow through engine room
  • inspect & repair sound insulation

Seasonal

Lubrication

  • change transmission fluid
  • grease control cable ends & engine mount threads
  • check injection pump & governor dipstick (if fitted)

6 months

Raw Water Cooling

  • check and change heat exchanger anode(s)

Drive Train

  • inspect propeller shaft anode
  • inspect the anode on a feathering propeller
Heat Exchanger Anode. Marine Diesel Basics

Electrical

  • keep battery(s) charged
  • check battery open circuit voltage with a multimeter
  • clean battery tops & terminals
  • check electrolyte levels in wet-cell battery(s)
  • add water to unsealed wet-cell battery(s)
  • check specific gravity of wet-cell battery(s)
  • load test a 12-volt battery

Yearly

Diesel Fuel

  • change the primary fuel filter
  • change the secondary fuel filter
  • bleed the fuel system (as needed)
  • check diesel tank(s) for contamination

Lubrication

  • lubricate ignition key slot

Raw Water Cooling

  • clean raw water intake thruhull
  • check emergency plug tied to seacock
  • check seacock open/closes smoothly
  • service raw water strainer
  • service raw water pump & impeller

Breathing

  • inspect and repair sound insulation

Electrical

  • test battery(s) with load tester

Drive Train

  • inspect propeller shaft
  • inspect strut
  • inspect cutlass bearing
  • inspect the propeller
  • inspect propeller nuts are tight & cotter pin
  • inspect a folding propeller
Marine diesel Basics change fuel filter & check propeller

Drive Train

  • check coupling between transmission & prop shaft
  • inspect the propeller shaft
  • inspect the strut
  • inspect the cutlass bearing
  • inspect the propeller anode
  • scrape the propeller, strut & shaft
  • inspect the propeller
  • inspect the propeller nuts & cotter pin
  • inspect a folding propeller
  • inspect the anode on a feathering propeller
  • grease a feathering propeller

1 – 2 Years

Drive Train
grease a feathering propeller

Coolant/Antifreeze
drain and replace worn-out coolant/antifreeze

click for free Maintenance Schedule Checklist
click for Free Maintenance Checklist

"Very useful, practical and to the point, a must on every boat. Good job Capt Berwick !! Write some more books."  Hristo Papakonstantopoulos.

Saildrives

Saildrive – Daily check
saildrive gear oil level & top up

Saildrive – Weekly (as needed)
scrape the propeller, strut & shaft
burp air from gear oil dipstick

Saildrive – Monthly
inspect and repair paint protection
clean raw water intake

Saildrive – 3 Months
check coupling transmission/prop shaft
inspect stern gland (stuffing box)

Saildrive – 100 – 250 hours
change gear oil in lower unit

Saildrive – 6 Months
inspect propeller shaft anode

Saildrive – Yearly
inspect exterior rubber fairing flange
inspect interior rubber sealing ring & water sensor alarm
drain raw water from saildrive (for lay-up)
inspect the propeller
grease a feathering propeller (see owner’s manual)

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