How to perform routine engine maintenance

In this episode, John Gamlin from our exclusive service department VesselTec explains the simple steps for an engine inspection. John goes down into the engine bay and walks us through WOBBLES and what to do if you find something abnormal.

This demonstration is done on a Lagoon 42 with 2 Yanmar Diesel Engines. Processes may differ depending on your engine type and make.


  • Isolate the engine by turning it off
  • Take off any loose clothing or tie up hair (if the engine has to be on)
  • Do a general inspection for anything that might stand out – smells, leaks, excess fuel or water in the bilge.
Routine Engine Maintenance


Routine Engine Maintenance


Salt Water System

  • Turn off water flow
  • Check strainer and empty debris
  • Check impeller for broken vains (if issues persist)

Fresh Water System

  • Check reservoir fluid levels
  • Open radiator cap and check levels, colour etc.


Engine Oil

  • Pull out dipstick
  • Clean dipstick
  • Put the dipstick back in (all the way) and back out
  • Check oil level and colour

Transmission Oil

  • Pull out dipstick
  • Clean dipstick
  • Put the dipstick back in (but do not screw) and back out
  • Check oil level and colour

You want your oil levels between the minimum and maximum markings (do not overfill). Colouring should not be milky (this could mean there is water inside), after a bit of use it should be black but not too black or thick.

Routine Engine Maintenance


  • Check connections and movement, if loose use a spanner to tighten.
  • If you find corrosion use a wire brush and then apply a protectant.
  • Also, check connections on battery switches


  • Check it is not fraying
  • Check it is not too loose or too tight (check mechanic what deflection it should have)

You may need to take off a belt guard to get to this area.

Routine Engine Maintenance
Routine Engine Maintenance


What to look for…

  • Water
  • Oil
  • Salt crystals (this indicates salt water has been in the area)
  • Corrosion

Areas to check…

  • Where hoses terminate
  • Check filters
  • Check other components e.g. gaskets

If you find any leaks attempt to find the cause, tighten anything that may be loose and clean the area so that you know whether the issue has persisted when you next check the area.


  • Turn engine on
  • Go to the side to see the water
  • Ensure there is a steady flow of water pulsing out


  • Ensure sound is smooth
  • No bad vibrations

If the sound is unusual contact your mechanic.

Routine Engine Maintenance