Question 1

Oil Leaks from Front and Rear Crankshaft Seals

Accepted Answer

Persistent weeping or pooling of oil beneath the engine, especially at the front timing cover or rear main seal area. You'll see oil misting onto the bellhousing or dripping from the sump. Age. The original rope-type rear main seal and lip seals up front harden and lose elasticity after decades. Heat cycling and long service intervals accelerate deterioration. Front seal: straightforward when doing the timing belt, pull the crank pulley, pry out the old seal, tap in a new one (lip facing inward), reassemble. Rear main: gearbox-out job. On early B18/B20 engines, a rope seal is shimmed into the block and cap; later B20s use a lip seal. Use OEM Volvo seals or quality aftermarket (Elring, Reinz). While you're in there, replace the sump gasket and cork end seals, they're cheap insurance. Torque sump bolts progressively to avoid distortion.

Question 2

Worn Valve Guides and Oil Consumption

Accepted Answer

Blue smoke on startup or deceleration, fouled spark plugs, rising oil consumption between changes (more than half a litre per 1,000 km). Valve stem seals harden and crack; valve guides wear oval. The B18 and B20 were never designed for modern extended oil change intervals, and many have seen neglect. Start with valve stem seals, they can be done head-on with a spring compressor and a bit of patience. If guides are worn beyond spec (check with a dial gauge), they'll need knurling or replacement. A full valve job isn't expensive at a competent machine shop. While the head's off, lap the valves, check the seats, and replace the head gasket. Torque head bolts to spec in the correct sequence, critical to avoid warping.

Question 3

Carburettor Issues (SU or Zenith-Stromberg)

Accepted Answer

Rough idle, hesitation, stalling when cold, flat spots under acceleration, poor fuel economy, black exhaust smoke. Gummed-up jets, worn throttle spindles, perished diaphragms, incorrect float height, or vacuum leaks. Ethanol in modern fuel accelerates varnish buildup. Strip and rebuild the carbs using a proper kit (needle, jet, diaphragm, float valve). Soak the bodies in carb cleaner, blow out all passages with compressed air, set float height to spec. Check throttle spindle play, if excessive, bushings are available or the body can be sleeved. Balance the carbs (on twin setups) using a Unisyn or vacuum gauges. Don't ignore vacuum hoses, any split or perished hose will lean out the mixture and cause erratic running.

Question 4

Worn Timing Chain or Belt Tensioner

Accepted Answer

Rattling or slapping noise from the front of the engine, especially on startup or idle. Loss of power, poor running, or misfires if timing has jumped. The B18/B20 uses a chain (early) or belt (later). Chains stretch over time; belts wear and fray. Tensioners lose spring tension or hydraulic pressure. Timing belt: replace every 10 years or 100,000 km, whichever comes first. It's a straightforward job, remove the radiator and front cover, align marks, fit new belt and tensioner, check tension with a gauge. Use OEM or Contitech belts. Timing chain: if rattling, check tension first (hydraulic tensioner may be stuck or weak). If chain is stretched, replace with a new chain, sprockets, and tensioner, the whole front cover comes off. While you're in there, do the water pump.

Question 5

Radiator Core Leaks and Corrosion

Accepted Answer

Coolant dripping from the radiator core, overheating, low coolant level without obvious external leaks, white crusty deposits on the radiator. Decades of heat cycling, poor coolant maintenance (tap water accelerates corrosion), road salt. The original brass cores rot through; plastic end tanks crack. If the core is leaking, don't bother with stop-leak, it's a temporary bodge. Have it recored or replace it. OEM replacements are available; budget options exist but often use thinner cores. Flush the system thoroughly, replace hoses and clamps, refill with a 50/50 mix of quality glycol coolant and distilled water. Bleed air from the heater circuit and top of the radiator.

Question 6

Thermostat Stuck Open or Closed

Accepted Answer

Stuck open: engine never reaches normal operating temperature (gauge sits low), poor heater output, high fuel consumption. Stuck closed: rapid overheating, gauge in the red, coolant boiling over. Corrosion or mineral buildup in the thermostat housing. Old thermostats lose calibration or seize. Test the thermostat by boiling it in a pan of water and checking opening temperature with a thermometer (should open around 82°C). If suspect, replace it, they're cheap. Use OEM or quality aftermarket (Wahler, Behr). Always fit a new gasket or O-ring, and bleed the system afterward.

Question 7

Heater Core Blockage or Leaks

Accepted Answer

No heat from the vents, sweet smell of coolant in the cabin, wet carpets, fogged windows, low coolant level. Corrosion and sediment buildup block the tiny heater core passages. Old cores develop pinhole leaks and drip onto the passenger footwell. Back-flush the heater core by disconnecting the hoses at the firewall and running water through in reverse. If blocked solid, it's heater core replacement time, the dashboard comes apart on most 140s, which is a full-day job. Fit a new core, replace the hoses, flush the system, and use proper coolant. Some fit an inline filter to prevent future blockages.

Question 8

Fuel Pump Failure (Mechanical or Electric)

Accepted Answer

Engine cranks but won't start, or starts then dies. Sputtering, loss of power, stalling under load. Mechanical pumps (early cars) wear out, diaphragms split, valves stick. Electric pumps (later cars) fail due to age, contaminated fuel, or running dry. Mechanical pump: unbolt from the side of the block, fit a new one with a new gasket. Prime it by cranking the engine. Electric pump (usually SU or Bosch): mounted under the car or in the boot. Check for power at the pump (12V with ignition on). If power is present but pump doesn't run, replace it. Fit an inline fuel filter upstream of the pump to keep debris out.

Question 9

Fuel Tank Rust and Contaminated Fuel

Accepted Answer

Rough running, clogged filters, stalling, rusty sediment in the fuel filter, fuel leaks at seams or filler neck. Moisture condenses in the tank, especially if the car sits unused. The uncoated steel rusts from the inside out. Ethanol in modern fuel accelerates corrosion and dissolves old sealants. Drop the tank, inspect internally with a torch. If heavily rusted, have it chemically cleaned and sealed (POR-15, Red-Kote, or similar). Replace the fuel sender seal, check the pickup sock for debris, fit a new filter. If the tank is rotted through, replacement is the only fix, original tanks are scarce, so aftermarket or stainless options exist. Always run a quality inline filter and replace it annually.

Question 10

Perished Fuel Hoses and Leaks

Accepted Answer

Fuel smell in the cabin or engine bay, visible drips or wet patches around hose connections, hard starting, rough running. Rubber degrades over decades. Ethanol fuel swells and cracks non-ethanol-compatible hose. Clamps loosen or rust. Replace every fuel hose you can see, from tank to pump, pump to carb/injection, return lines. Use proper fuel-injection-rated hose (SAE J30 R9 minimum) even on carb cars. Fit new stainless clamps. Check the filler neck hose and vent hoses, they rot invisibly.

Question 11

Alternator Failure or Weak Charging

Accepted Answer

Battery warning light stays on, dim lights, flat battery after short drives, voltage drops below 13V at idle (with engine running). Worn brushes, failed diodes, slipping belt, corroded terminals. The Bosch alternators are robust but eventually wear out. Check belt tension and condition first, replace if cracked or glazed. Measure voltage at the battery with engine running, should be 13.5-14.5V. If low, remove alternator and test on a bench or have it rebuilt (brushes, diodes, bearings). Clean all earth straps and battery terminals with a wire brush. Uprated alternators (55A or 70A) are available if running modern accessories.

Question 12

Wiring Loom Corrosion and Brittle Insulation

Accepted Answer

Intermittent faults, instruments cutting out, no start, flickering lights, burning smell, smoke from under the dash. 50-year-old insulation cracks and shorts. Moisture corrodes bullet connectors, crimps, and fuse blocks. Rats and mice chew wiring. Trace faults systematically with a multimeter. Clean or replace corroded connectors. Re-solder dodgy crimps. Wrap bare wires in heat-shrink or proper automotive loom tape. If the loom is truly rotten, aftermarket replacement looms are available, fitting one is a week-long job but worth it for peace of mind. Always carry spare fuses, a test light, and a basic wiring diagram.

Question 13

Faulty Ignition Switch or Starter Relay

Accepted Answer

Key turns but nothing happens, no dash lights, intermittent starting, click but no crank, or starter spins continuously. Worn contacts in the ignition switch, corroded relay terminals, failed solenoid. Test for 12V at the starter solenoid with the key in the start position. If voltage is present but no crank, starter or solenoid is faulty. If no voltage, work backward to the ignition switch and relay. Clean all connections, replace the relay if suspect (cheap and common), and replace the ignition switch if contacts are burnt. Some fit a push-button starter as a backup.

Question 14

Worn Clutch (Manual Transmission)

Accepted Answer

Slipping under load (engine revs rise without acceleration), high biting point, difficulty engaging gears, juddering on takeoff, burning smell. Friction material wears thin, pressure plate weakens, oil contamination from a leaking rear main seal. Gearbox-out job. Fit a new clutch kit (plate, cover, release bearing). Inspect the flywheel for cracks or hot spots, have it skimmed if scored. Replace the spigot bearing while you're in there. If the rear main seal is leaking, fix it now, oil on the clutch will destroy it within weeks. Bleed the hydraulic system and adjust the pedal freeplay to spec.

Question 15

Gearbox Oil Leaks (Manual and Automatic)

Accepted Answer

Oil pooling under the gearbox, wet bellhousing, low oil level, whining or grinding from the box. Perished seals at the input shaft, output shaft, or selector shaft. Overfilling or worn gaskets. Jack the car, identify the source. Input shaft seal: gearbox out. Output shaft seal: straightforward, pull the propshaft, lever out the old seal, tap in a new one. Selector shaft seals: remove the tower, replace the O-rings. Top up with the correct grade of oil (usually SAE 80W or ATF, check the manual). Overfilling causes leaks and foaming, drain to the correct level.

Question 16

Worn Propshaft Centre Bearing

Accepted Answer

Vibration or droning at highway speeds, clunking on takeoff or gearshifts, visible play in the propshaft. The rubber-mounted centre bearing wears out, especially if the car's been off-road or the propshaft is unbalanced. Support the car on stands, remove the propshaft (mark the flanges for correct reassembly), replace the centre bearing and its rubber mount. Check the propshaft for straightness and balance, a bent shaft will destroy bearings quickly. Torque the flange bolts to spec and use new locknuts.

Question 17

Differential Whine or Clunking

Accepted Answer

Whining or howling from the rear axle, especially under load or deceleration. Clunking when changing direction. Worn diff bearings, incorrect backlash, low oil, contaminated oil, worn pinion or crown wheel. Check the diff oil level and condition (should be clean, not milky or metallic). Top up with the correct grade (usually SAE 80W-90 or 85W-140). If noise persists, the diff needs stripping and inspection. Worn bearings or gears require replacement, not a DIY job unless you have experience setting backlash. A clunking diff often just needs new halfshaft bolts or a shimmed pinion flange.

Question 18

Worn Front Suspension Bushings (Control Arms, Anti-Roll Bar)

Accepted Answer

Clunking over bumps, steering wander, imprecise turn-in, excessive tyre wear, steering wheel off-centre after cornering. The rubber bushings in the lower control arms, anti-roll bar mounts, and upper spring seats perish and split. Road salt and heat accelerate decay. Jack the front end, inspect all bushings visually and by levering with a bar. Replace any that are split, cracked, or allow excessive movement. Polyurethane bushings are available and last longer but transmit more road noise. Use a press or large vice to fit new bushings, heat the arm to ease installation. Torque all bolts with the suspension at ride height to avoid pre-loading the bushings. Get a four-wheel alignment afterward.

Question 19

Tired Shock Absorbers

Accepted Answer

Wallowing over bumps, nose-diving under braking, excessive body roll in corners, bouncing after hitting a bump (more than one oscillation). Internal seals wear out, damping fluid leaks, gas charge escapes. Shocks don't last forever, 80,000 km is typical. Bounce each corner of the car and watch the rebound, it should settle within one cycle. If it bounces more than once, the shock is done. Replace in pairs (both fronts, both rears). Fit quality units, Bilstein, Koni, or Boge are all superior to cheap pattern parts. If the car's lowered or you want a firmer ride, adjustable Konis are worth the extra cost.

Question 20

Steering Box Wear or Leaks

Accepted Answer

Excessive play at the steering wheel (more than 1" of movement before the wheels turn), wandering on straight roads, groaning or stiffness when turning, hydraulic fluid leaking from the box. Worn internal gears, tired seals, incorrect adjustment, low power steering fluid, contaminated fluid. Check fluid level and condition (should be clear, not brown or burnt-smelling). Top up with ATF Dexron III. Adjust the steering box pre-load (screw on top of the box), tighten until play is removed but steering isn't stiff. If leaking, rebuild kits are available but it's a fiddly job. Replacement boxes are common at breakers. While you're under there, check the steering column UJs for wear, they're a common source of clunking.

Question 21

Brake Master Cylinder Failure

Accepted Answer

Spongy or sinking brake pedal, loss of braking effort, fluid leaking at the back of the master cylinder, brakes locking on (rare). Internal seals wear out, allow fluid to bypass the pistons. Corrosion in the bore. Moisture contamination. Bench-test the master cylinder by blocking the outlets and pumping the lever, it should hold firm. If it sinks, rebuild or replace. Rebuilds are possible but replacement is easier and more reliable. Use OEM or A

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142 / 144 / 145 known problems