Crucial Engine pt. 1 Points Flashcards
What does an engine lubrication system fitted with a relief valve do?
Limit the maximum oil pressure to the bearings
What does viscosity mean in terms of oil?
Oil density
What measurement tool is used to check coolant for the anti-freeze content?
Hydrometer
Why is it important to maintain engine valve clearance?
It effects engine power
What engine oil is most suitable for a modern CI engine?
SAE5W/40
What is a semi-synthetic lubricant?
A mixture of organic and man-made lubricants
What is the name given to an engine without a pressure-charger induction system?
Naturally aspirated
What does a rotary engine have?
An epitrochoidal liner which turns a triangular rotar
When does maximum compression occur?
At TDC
If valve clearances are too large, when will the valves open and close?
Open later and close earlier
How does heat from the engine cylinder pass through the cylinder walls?
Conduction
In the diagram with the circle and the x at the top, what does the x represent?
The valve overlap
What could the problem be if there are air bubbles in the cooling system when the engine is running?
Blown head gasket
What are the 3 most likely causes of high fuel consumption?
Excessively worn piston rings, valves or gaskets
When replacing a blown cylinder head gasket what is it important to do?
Check the cylinder head for distortion
What is water in the engine oil is most likely caused by?
Defective liner seals
What is a likely symptom of a blown head gasket?
Poor engine performance and engine overheating
A compression ignition engine emits blue smoke when under load. What is the most likely cause?
Broken piston rings
Which component needs to be removed when fitting a cylinder compression gauge to a spark ignition engine?
Spark plug
Where is the oil stored in a wet sump lubrication system?
Engine sump
What is the distance between BDC and TDC related to?
The stroke
When refitting a piston to a compression ignition engine, how should the gaps in the piston ring be spaced?
120 degrees apart with no gaps facing the thrust surface
What is the purpose of cylinder honing or ‘glaze busting’?
To remove the highly polished surface from the cylinder
Why are supplemental coolant additives (SCA) sometimes added to CI engines?
Decrease the cavitation point of coolant
Which measurement requires a precision straight edge and feeler gauge?
Checking for cylinder head warp
What is a normal compression ratio of a CI engine?
16:1 to 22:1
In what type of CI engine is the combustion chamber machined into the piston crown?
Direct injection
When stripping an engine, you are asked to find out its cubic capacity, which action would assist you to find the correct answer?
Measure the bore, the distance the piston moves from BDC to TDC and count the number of cylinders
What formula can be used to calculate compression ratio?
Swept volume + clearance volume / clearance volume
What is the main difference between a wet sump and dry sump lubrication system?
A wet sump requires an external oil supply tank and a scavenge pump
In a full flow lubrication system, what order of components does the oil flow through?
Filter first, then something else
What is specific heat capacity?
The quantity of heat required to raise the temperature of 1kg of a substance by 1K or 1 degree C
What are the unit abbreviations used to show engine power and torque?
KW and Nm
What should you do to determine piston clearance accurately?
Don’t slide a feeler gauge between the piston and cylinder
What is the suitable oil viscosity for a modern petrol engine?
SAE 10/40
A coolant leak from behind the dashboard could suggest what?
A leaking heater matrix
