Engines Flashcards
What is the firing order on a 4 cylinder engine
1342
What is the firing order on a 6 cylinder
153264
What it the ideal fuel to air ratio of a diesel engine
14.7 : 1 by mass
How is a glow plug controlled
Timer and relay
How to test a glow plug
Using a multimeter aim for 1 to 5 ohms of resistance
What does a charge air cooler do
Increases the density of the intake by cooling the temperature
How to time a fuel pump
By ensuring the pump is at tdc using a dti
What does ci and si stand for
Compression ignition and spark ignition
What is thermal efficacy
The amount of heat which is used for useful work
Volumetric efficacy
The amount of time it takes to fill a cylinder
What is mechanical efficacy
A way to measure the effectiveness of a systems performance
What does ohv and ohc stand for
Overhead valve (pushrod) and overhead cam (car)
If the crankshaft rotates once how many times does the camshaft rotate
Half a turn.
What is the difference between indirect and direct fuel injection
Direct injection is premixed air and fuel and indirect uses a mixing chamber above the combustion chamber to fix the 2 before injection
What is the face of a block called
The deck
Why are cylinder walls hatched
To allow an oil film to stick onto them improving lubrication
How do you fit piston rings
120 degrees apart and follow manufacturer guidelines
Name the piston parts
Crown. 3 rings 2 compression one scraper. The skirt, gudion pin, con rod, big end cap
What measument is a dyno in
Kilawatt
What is the 4 stroke cycle
Intake, compression, power, exaust
What are major and minor forces
It is the faces where the piston slaps against causing ovality
What is the purpose of a multi cylinder engine
To allow balance and efficiency
What is swept volume
Top dead centre to bottom
What is clearance volume
It is tdc to block
Total volume is
Clearance and swept volume
What is compression ratio
It is total % clearance volume
How do you work out cubic capacity
Top to bottom and times by the amount of cylinders
What is thermal conductivity
The rate of which an object conducts heat
What is thermal expansion
The rate of which an object expands when heated
What are the 3 types of heat transfer
Conduction, convection and radiation
What is coolguard
Ethylene glycol
What is the benefit of coolguard pg
Propylene glycol it is less toxic
Hydrometer measurements for good coolant
Water = 1g cm
coolant = 1.11 g cm
What is a refractometer
It is a device which reflects light allowing it to determine the coolant strength
What does miscible mean
When 2 fluids form a mixture of
What valve is bigger
The intake valve is slightly larger to increase volumetric efficacy
What is blow by
It is the piston carrying unburnt, corrosive gassed and steam into the crankcase
What is basic lubrication
Splash and mist
What is boundary lubrication
Required for sliding engine components that don’t need a pressure feed
What is hydrodynamic lubrication
It is where an oil needs pressurising to be entered like a main crank bearing needs this high pressure in order to keep an oil film
What is hydrodynamic lubrication
It is where an oil needs pressurising to be entered like a main crank bearing needs this high pressure in order to keep an oil film
During an engine cylinder shutdown test it reported that cylinder 3 revealed a 25 percent drop what could this mean
This cylinder is completely fine due to the drop
How is crankshaft end float adjusted
Using thrust bearing/ shims
What is plastiguage used for
To check bearing clearance
How should you install piston rings
Away from minor and major force face
And 120 degrees apart
What will a turbo inter cooler do
Decrease air temp and increase air density
As the engine increases heat what will happen to the valve clearances
They will get closer/ smaller tolerance
What does octane rating refer too
Fuels auto ignition point for petrol/ fuel
An engine is burning excessive oil what could be a cause
Stem seals
What do hydraulic cam lifters do
Self adjust allowing it to have less maintenance
How do you know what way up a piston ring goes
Manufacturer marking
How do you measure bore ovality
Using a borescope and you take reading from 3 different points
What is multipoint injection
It is an electronic injection system
What does common rail refer too
All injectors are fed by one ‘common rail’
How could a con rod become bend 3 reasons
Hydrlock due to excessive fuel
Hydrolock from water in exhaust
Incorrect valve timing
This machine cranks but no Vapor is coming out of exaust and it won’t start what should you do
Check fuel level / emergency tap
Check fuel filters
Ask customer what happened
Check service advisor
What affect would a seized closed oil pressure relief valve have on an engine
Low oil pressure at low rpm
An t belt would cause what?
Damage to bearings
What would exessive engine valve clearance cause
Damage to parts of/ retard timing
Why is it important to read and clear codes on a service
To help with diagnosing faults
What is the 3 jobs of an ecu
Fuel quality, fuel timing and fuel duration of injection
How do you carry out a compression test
Remove spark plug / injector / glow plug
Remove ability to start engine
Add gauge, and crank engine
Wait till it gets to a stable compression
What is a wet compression test
Add a bit of oil to the cylinder to fill a possible crack in the piston for example and if the measurement comes back better after adding oil you know the bottom end is damaged
What is a cylinder leakage test
Lock system at tdc , introduce air through injector / glow / spark plug fitting. Hold at 10 bar and monitor where the air escapes by using gloves to cover exits, eg exaust exit/ intake / radiator cap/ dipstick
What is a turbo hot side
Turbine is hot compressor side is cold
What would happen if your engine pressure relif valve is stuck closed
Low rpm would be fine but high rpm would have extreme pressure
What is the flash point of diesel
62 degrees
What is flash point (diesel)
Point of heat required to vaporise the gas
What is the auto ignition temperature of diesel
Approximately 210 degrees
