The alternator and raw water pump on many engines are driven by a V-belt. How do you check belt condition and tension?

A. Condition: look for cracks, fraying, glazing, or missing chunks — replace if any present. Tension: press midway between pulleys — correct tension gives approximately 10-15mm deflection under moderate thumb pressure (check engine manual for exact specification). A loose belt slips and squeals; too tight damages alternator bearings

B. Tighten the belt until it has zero deflection — this prevents slipping under high load

C. Replace V-belts only when they break — visual inspection gives no useful information

D. V-belts never require adjustment — they are self-tensioning

A. Compression ignition: diesel fuel is ignited by the heat of highly compressed air (compression ratio ~22:1) — no spark plugs are used. Fuel is injected into the compressed air at the moment of ignition

B. Diesel engines work at lower compression ratios than petrol engines for safety

C. Diesel engines use spark plugs but fire in a different sequence to petrol engines

D. Diesel engines use carburettors to mix fuel and air before compression

A. Compression, ignition, induction, exhaust — the compression happens before air enters

B. Induction (air in): piston down, air drawn into cylinder. Compression: piston up, air compressed to high temperature. Power (ignition): fuel injected, combustion drives piston down. Exhaust: piston up, exhaust gases expelled

C. Ignition, compression, induction, exhaust

D. Induction, power, compression, exhaust