Diesel Engine Course Flashcards
How does a diesel engine work?
- a reciprocating piston engine
- ignites a compressed fuel-air mixture to create a force that push down on the pistons which in turn push against the crankshaft
- that force creates rotational energy
reciprocating
hin- und her
crankshaft
Kurbelwelle
Biggest difference to petrol engine?
A petrol engine need a spark plug to ignite the fuel-air mixture
A diesel engine auto ignites when a certain temperature and pressure is reached
A diesel engine has two main requirements:
Air supply
Clean fuel
das Ansaugrohr
inlet manifold
zerstaeubt
atomised
1/4 engine sequence
SUCK / INTAKE
the inlet valve opens
air is drawn in through the air filter
through the inlet manifold into the chamber
by the vacuum created from the cylinder
drawn
gezogen
2/4 engine sequence
SQUEEZE / COMPRESSION
at the bottom of the cylinder stroke the inlet valve close,
preventing air escaping back up the inlet manifold, as the cylinder rises as part of its upward stroke
Zylinderhub
cylinder stroke
3/4 engine sequence
BANG / POWER
the pistons compresses the air heating enough to ignite the atomised fuel injected by the injector into the cylinder
the ignited fuel-air mixture forces the piston back down the cylinder chamber and in turn, rotating the crank shaft
4/4 engine sequence
BLOW / EXHAUST
once at the bottom of the stroke, the exhaust valve opens and the rising cylinder forces the exhaust gasses out of the chamber.
Once at the top of the cylinder, the exhaust valve closes, the inlet valve opens and the process starts again.
how much air in relation to the fuel?
14.5 times that of diesel by weight
the 4 strokes of a diesel engine:
Intake – The piston moves down, and air enters the cylinder.
Compression – The piston moves up, squeezing the air and making it very hot.
Power – Fuel is injected, ignites from the heat, and pushes the piston down.
Exhaust – The piston moves up again, pushing out the burned gases.
WOBBLE
Water: Check the raw water seacock is turned on. Check the coolant water level and top up if necessary.
Oil: Check the oil levels and top up if necessary.
Belt: Check any belts, such as the alternator drive belt, for tension and wear.
Bilges. Check the bilges for water, oil and black dust which could have come from a worn fan belt.
Leaks: Check all pipe connections, water pump and stern gland/s for leaks especially if there is excess water in the bilges.
Exhaust: Once the engine has started, check that water is being ejected from the exhaust.
key areas to check before starting a engine
cooling system,
fuel system,
lubrication,
air system,
engine electrics,
engine driven bilge pump
3 main causes of fire?
galley
marine engine
electrical
Strainer
elements of the seawater cooling system
seacock
strainer
fresh seawater pump
syphon breaker
heat exchanger
exhaust injection
die Dichtung
gasket
A creamy substance in the oil indicates …
… that water is mixing with it possibly due to a leaking cylinder head gasket. Have the engine looked at by a qualified diesel mechanic.
An increase in oil levels indicates …
…diesel is getting into the oil, usually due to faulty injectors. These can be removed and serviced.
Gritty oil indicates …
…possible wear (Abnutzung) inside the engine. The engine should be flushed out, the oil replaced and the engine and oil monitored to see if the problem reoccurs.
Very black oil with little viscosity means…
…the engine needs an oil change and oil filter change.
Black smoke can indicate …
… the engine is labouring due to a rope round the prop, dirty hull, blocked engine air filter, faulty injectors or a faulty injection pump.
Blue smoke indicates …
…the engine is burning oil. This can be due to a faulty turbo or an internal problem with the engine.
What are you doing with a Dipstick?
oil level check
The most common causes for the alternator not delivering power are:
Slipping or broken drive belt.
Loose connections at the alternator, battery or anywhere else in the charging circuit.
Faulty battery
If the starter battery is fully charged and you cannot hear the ‘clunk’ when attempting to start the engine, there are four common potential issues.
The starter motor is jammed. Try tapping the starter motor housing with a hammer using moderate force.
The solenoid is not operating due to being jammed. Try tapping the solenoid with a hammer with light force.
The solenoid energising circuit is not operating. Check the fuse.
The power circuit is not connected. Check all battery isolation points, cabling, and the starter motor fuse if fitted.
What is a Glow Plug?
a glow plug is used to apply heat to the engine to support starting.
abgenutzt
worn
Check the area around and below the alternator for signs of black dust, which would indicate…
… that the belt is worn and may need to be replaced.
Turbos allow a smaller engine to create the power equivalent to a much larger engine but there are some limitations:
The turbo does not provide additional power at low engine revolutions.
They put the engine under a lot more stress and wear.
There is a significant increase in heat generated within the engine bay, with a hotter exhaust system so specialised exhaust systems are needed to handle the increase in temperature.
They add to the complexity of the engine, so are harder to fix when out on the water.
Significantly more expensive to purchase.
Much higher maintenance costs.
Turbo charging provides …
…an increase in power by supplying air at a positive pressure to the combustion chamber allowing a greater air-fuel mixture and creating more power.
A wastegate…
…allows the excess exhaust gasses to bypass the turbo.
Blue smoke from the exhaust can be an indication that …
… the turbo may have an oil leak.
A intercooler…
…cool the compressed inlet air before it enters the engine
What are Turbos for?
Turbos are a very effective way to increase engine power for a given size and allows engines to be installed in a vessel that are smaller and lighter than a normally aspirated version of the same size.
die Magnetspule
solenoid
syphon breaker …
bleed the air from the cooling system
Black or grey smoke indicates…
poor combustion
Black or grey smoke, 7 causes:
- Excessive marine growth on the propeller
- Excessively dirty hull
- Dirty fuel
- Fouled injectors or injector pump
- Fouled air filter
- Turbocharger seal failure
- Fire in the engine compartment
Blue smoke indicates…
… oil is burnt in the combustion chamber.
Blue smoke, 4 causes:
- Incorrect oil grade
- Diesel fuel in the oil
- Excess pressure in the crankcase
- Turbo oil seal
das Motorgehaeuse
crankcase
die Dichtung
seal
White smoke occurs …
… when unburnt diesel enters the exhaust.
White smoke, check…
The condition of the fuel.
The condition of the fuel filters.
Abwuergen
to stall
A diesel engine needs three things to operate:
fuel, air, and compression
Fault-finding - Engine Stalls (5)
- wrapped a rope around the propeller!
- Lack of fuel
- Contaminated fuel
- Blocked or damaged hoses
- Blocked fuel tank vent
