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Oil leaks from multiple places, rough idle, high oil consumption, smoke from the engine bay. Sometimes the oil filler cap pops off under pressure.

The PCV (positive crankcase ventilation) system recirculates blow-by gases. The flame trap (a mesh filter) and oil separator box get clogged with sludge, especially on short-trip cars. Blocked breathers create crankcase pressure, which forces oil past every seal.

Replace the flame trap (cheap, about $5-10, part lives under the intake manifold) and clean or replace the oil separator box. Volvo designed this as a service item, but many owners forget it exists. Also replace any collapsed or oil-soaked breather hoses. Do this every 50,000 km or if you see oil leaks appearing everywhere at once.

Belt snaps, engine stops immediately. If it's an interference engine (all B21/B23 are), valves hit pistons. Game over. Water pump failure causes overheating, coolant loss.

Timing belts are a wear item. Volvo says 10 years or 100,000 km (160,000 km on later four-cylinders). Water pumps fail from bearing wear or seal leakage.

Replace the timing belt, tensioner, and idler pulleys as a kit. Do the water pump at the same time, it's right there, and the labour overlaps. Use OEM or quality aftermarket (Aisin, Gates). Torque the crank pulley nut to spec and align timing marks carefully. If you've never done this, get a mate who has or pay someone. Bentley or Haynes manual walks you through it.

Rough idle, hesitation, hard starting, fuel smell. One or more cylinders run lean or rich. LH 2.4 injectors (yellow-top) can leak when hot.

Old fuel leaves varnish deposits. Injectors clog or seals perish. The 240's continuous injection system (K-Jetronic or LH) is sensitive to fuel quality. Leaking injectors wash down cylinder walls, dilute oil, and create a fire risk.

Remove injectors, send them for ultrasonic cleaning and flow testing (many shops do this for $10-20 per injector). Replace O-rings and seals. If they're beyond saving, get a tested set from a breaker or buy new. For LH 2.2, use black-top injectors. LH 2.4 uses yellow-tops. Do not mix them, different flow rates.

Car cranks but won't start, or cuts out randomly. Sometimes you'll hear the pump prime when you turn the ignition on; other times, silence.

The fuel pump relay (white plastic block, usually under the driver's seat or in the engine bay) is a known weak point. Contacts corrode or the solder joints crack. Pumps themselves can fail, especially if the tank's run low and sucked up debris.

Swap the relay first, cheap, easy. If that doesn't work, bridge terminals 2 and 30 (or 87 and 30, depending on type) with a wire to manually run the pump for testing. If the pump runs, replace the relay. If not, check the pump itself. Pre-pump replacement involves dropping the fuel tank. Main pump is under the car near the rear axle (early cars) or in-tank (later ones). Use a Bosch or genuine Volvo pump.