Fishing Craft Technology (1+1)

Unit 5 - Marine Engine and propulsion system

5.7. Care and Maintenance of engine

Performance of an engine degrades with time as its components deteriorate or wears out. Cleaning, inspection and maintenance of various parts have to be carried out periodically for the purpose of smooth engine operation and to avoid engine troubles.
Maintenance can be classified as

• Routine/ scheduled maintenance.
• Preventive maintenance.
• Breakdown maintenance.

1) Preparations before starting
The following points need to be checked for starting any engine

• Check batteries for specific gravity, loose terminal connections, and proper battery voltage for an electrically started engine.
• Check the air pressure in the air bottles and fill it to 30 kg/cm2 for air started engines
• Check lubrication oil level of engine gearbox, turbo charger and replenish if low.
• Remove water from fuel service tank, strainers, fuel pumps and also purge air from fuel system (if overhauled)
• Pre lubricated the engine either manually, hand pump or electrically driven pump as the case may be and also run the cooling water pumps.
• Check and oil the valves if they are hand lubricated.
• Preheat the cooling water in cold weather or cold temperature places.
• De clutches the engine from propeller shaft.
• After all the above checks are performed before start the engine, observe its performance for sometime and then the load to the engine can be given

2) Precaution for stopping the engine

• Make sure the air bottles have sufficient air for next starting. It is advisable to keep air bottles always with the maximum of 30 kg/cm2 Pressure
• Lubricate manually the valves etc if required to prevent sticking.
• Run the engine at no load before stopping
• Check the condition of bearing, crank pin etc. by opening side cover if engine is overhauled recently.
• Drain out the cooling water for long shut downs.
• Operate the auxiliary cooling water pump and lubrication oil pump for larger engines so that the engine is cooled effectively.
• For supercharged engines observe the rotation and stopping supercharger. The speed of supercharge should reduce gradually. Abrupt reduction of speed means defective supercharger.
• List out the repairs to be carried out before next operation.

The maintenance cycle varies according to the type of engine, service conditions purpose etc. and to greater extent determined by each manufacturers. However the following may form a guideline or reference for the maintenance specially the routine and preventive maintenance of an engine.

• Daily inspection
• Inspection at every 100hrs. Or 10 days
• Inspection at every 500hrs. of operation or 1.5 months
• Inspection at every 1000hrs. of operation or 3 months
• Inspection at every 3000hrs. of operation or 6 months
• Inspection at every 6000hrs. of operation or 1 year.

 
i) Daily inspection

• Inspect the quantity of lubricant oil in the sump of the engine gearbox & super charger and make up if necessary.
• Inspect quantity of cooling fresh water in the tank make up if necessary.
• Remove water if present in fuel system.
• Grease or oil the parts, which require manual lubrication.

ii)Inspection at 100 hours

• Cleaning of lubricant oil, fuel oil filters, air filters.
• Inspection of V-belts for tension.

iii)Inspection at 500 hours

• Cleaning of exhaust valve and capping
• Testing of injection pressure and atomizing conditions of injector valves
• Replace of engine and super charger lubrication oil

iv)Inspection at 1000 hours

• Inspection of tightness of cylinder head bolts and connecting rod bolts
• Checking of valve taper clearances and fuel timings
• Cleaning air filters for superchargers

v)Inspection at 3000 hours

• Decarbonisation or top over hauling
• Inspection of reverse gear thrust bearing
• Inspection at 6000 hours
• Major over hauling