Question 1

Oil leaks from rear main seal

Accepted Answer

Oil weeps or pours from the back of the engine, usually visible around the bellhousing. Can soak the clutch on manual cars. The B18 and B20 rear main seals are old-school rope-type or early lip seals that harden and fail with age. Heat cycling and sitting for long periods accelerates this. Pull the gearbox (or engine, your choice of hell). Replace the seal. It's not an expensive part, but it's a full weekend job. Use genuine Volvo or quality aftermarket seals, cheap ones leak within months. While you're in there, replace the clutch if it's oily.

Question 2

Piston ring wear and oil consumption (B18/B20)

Accepted Answer

Blue smoke on startup or under load. Engine uses a litre of oil every 500-1000 km. Exhaust tips go black and sooty. Worn piston rings. These engines can do 250,000+ km, but eventually the rings lose tension. Poor maintenance (infrequent oil changes, cheap oil) accelerates wear. Pull the engine, hone the bores, fit new rings. If the bores are scored or tapered beyond spec, you'll need a rebore and oversize pistons. Budget $1500-3000 depending on how far gone it is. A B18 or B20 shortblock from a wreck is sometimes cheaper than a rebuild.

Question 3

Timing gear wear and rattle (B18)

Accepted Answer

Rattling or chattering noise from the front of the engine, especially on cold start or at idle. Sometimes a metallic ticking that doesn't go away when warm. The B18 uses fibre timing gears (early models) or nylon-toothed gears that wear and crack. They were designed to fail quietly rather than grenade the engine, but eventually they strip teeth or disintegrate. Pull the timing cover, inspect the gears. Replace with steel gears if you want it sorted for good, repro steel gear sets are available. Takes a few hours if you know what you're doing.

Question 4

Head gasket failure

Accepted Answer

Overheating, white smoke from the exhaust, coolant loss with no visible leak, mayonnaise in the oil filler cap. Old gaskets, overheating events, warped head from previous bodge jobs. The B18 and B20 are robust, but decades of use and abuse take their toll. Pull the head, have it pressure tested and skimmed if warped. Fit a new genuine Volvo gasket (don't cheap out). Replace head bolts. Torque sequence matters, follow the manual. Budget $800-1500 depending on machine shop costs.

Question 5

Bosch D-Jetronic injection faults (B20E/B20F)

Accepted Answer

Poor starting, lumpy idle, hesitation, black smoke, random stalling. Sometimes won't start at all. The D-Jetronic system on the 1800E and 1800ES is primitive by modern standards. Injectors clog or leak, the airflow sensor (pressure sensor) drifts, wiring corrodes, the cold start injector fails. Parts are rare and expensive now. Diagnose methodically. Check fuel pressure first (should be ~28 psi). Test injectors for spray pattern and leaks. Check all grounds, these systems are *very* sensitive to poor earths. The airflow sensor is a common culprit and NLA from Volvo. Some people retrofit Weber carbs or SU setups and bin the injection entirely. Injector refurbishment services exist but aren't cheap.

Question 6

Valve adjustment neglect

Accepted Answer

Ticking or tapping noise from the top end. Loss of power. Hard starting. The B18 and B20 use solid lifters that need adjustment every 10,000 km. Most owners ignore this. Valves tighten up over time, leading to poor sealing and burnt valves. Set the valve clearances to spec (inlet 0.4mm, exhaust 0.4mm cold, or consult your manual for hot settings). Takes an hour and costs nothing. If valves are burnt, the head needs to come off.

Question 7

Radiator corrosion and leaks

Accepted Answer

Coolant leaks from the core or end tanks. Overheating. Brown sludge in the system. Original brass/copper radiators corrode internally, especially if the coolant hasn't been changed in decades (common on barn finds). Plastic-tanked aftermarket units crack at the crimp joints. Recore the original radiator ($300-600) or fit a modern aluminium unit. Flush the system thoroughly before fitting a new rad, old rust and scale will kill it quickly. Use proper 50/50 coolant, not water and dishwashing liquid.

Question 8

Thermostat failure

Accepted Answer

Engine runs cold (heater blows lukewarm, fuel economy suffers) or overheats quickly. Thermostats stick open or closed. Age and crud in the coolant are the culprits. Replace the thermostat. Cheap part, easy job. Test it in a pot of boiling water before fitting, some repro units are junk.

Question 9

Water pump bearing failure

Accepted Answer

Squealing or grinding noise from the front of the engine. Coolant leak from the weep hole. Overheating. Old bearings, worn seals, corrosion. The pump is exposed to coolant and heat cycling for decades. Replace the water pump. They're available and not expensive. Takes a couple of hours with basic tools.

Question 10

Heater core leaks

Accepted Answer

Coolant smell in the cabin, damp carpet on the passenger side, steamed-up windscreen, coolant loss. The heater core is a tiny radiator tucked up behind the dashboard. They corrode and leak, especially if the coolant is old or the system has been run on plain water. Pull the dashboard. Yes, the entire dashboard. It's a bastard of a job. Budget a full weekend and some swearing. Replace the core, flush the system, refill with fresh coolant. Some people bypass the core if the heater isn't essential, run a loop of hose and forget about it.

Question 11

Fuel tank rust and sediment

Accepted Answer

Fuel starvation, clogged filters, rough running, won't start. Brown gunk in the fuel filter. Steel fuel tanks rust from the inside, especially if the car has sat for years with stale fuel. Water gets in through poor sealing or condensation. The rust flakes off and clogs everything downstream. Drop the tank, inspect it. If it's rusty, have it chemically cleaned and sealed (POR-15, Red Kote, etc.) or replace it. Repro tanks are available but not cheap ($500+). Fit an inline fuel filter and replace it regularly. Flush the fuel lines.

Question 12

SU carburettor issues (B18)

Accepted Answer

Poor idle, flat spots, hesitation, black smoke, fuel smell, poor starting. The SU carbs on early P1800s are simple but need maintenance. Jets wear, needles wear, diaphragms split, float needles stick. Old fuel varnishes everything. Most owners don't understand how SUs work and make it worse. Strip, clean, rebuild. Replace the diaphragms, needles, jets, float valves. Set the float height correctly. Balance the carbs with a Unisyn or similar tool. There's a learning curve, but once you've done it a few times it's straightforward. Budget $200-300 for a rebuild kit.

Question 13

Fuel pump failure (mechanical and electric)

Accepted Answer

Engine cuts out, won't restart, or runs lean and misfires. You might hear the electric pump ticking rapidly or not at all. Mechanical pumps (B18) wear out, diaphragms split, valves stick. Electric pumps (later B20) seize or burn out, especially if the fuel filter is clogged and they're working too hard. Replace the pump. Mechanical pumps are cheap and easy. Electric pumps are also cheap, but get a decent one (Facet or SU type). Fit an inline filter *before* the pump to protect it.

Question 14

Fuel line corrosion and leaks

Accepted Answer

Fuel smell, visible drips, puddles under the car. Sometimes a rough idle or hesitation if air is being drawn in. Steel fuel lines rust through, especially along the sills and under the boot floor. Rubber hoses perish and crack. Replace corroded sections with Kunifer (copper-nickel) line or braided hose. Do not use cheap rubber fuel hose, it'll perish and leak again. Check every inch of the fuel system, from tank to carbs/injectors. Fix it properly.

Question 15

Lucas-derived wiring faults (early Jensen-built cars)

Accepted Answer

Intermittent starting, dead instruments, lights that work when they feel like it, random short circuits. Early Jensen-built P1800s (up to 1963) used Lucas electrical components. The wiring is primitive, grounds are poor, and connections corrode. Decades of bodge repairs make it worse. Trace every fault methodically. Clean all earth points. Replace corroded bullet connectors with crimped terminals. Consider rewiring the car section by section with a modern harness if it's truly awful. Check the fuse box, early ones are rubbish.

Question 16

Voltage regulator and dynamo/alternator faults

Accepted Answer

Battery won't charge, instruments flicker, lights dim, battery goes flat overnight. Early cars had dynamos and separate regulators that fail. Later cars (post-1970) had alternators, which are more reliable but still die eventually. Voltage regulators stick or burn out. Test the output at the dynamo/alternator, should be ~14V with the engine running. If it's low, check the regulator first (cheap, easy to replace). If the dynamo is shot, convert to an alternator, kits are available and it's a worthwhile upgrade. Rebuild or replace the alternator if that's what you have.

Question 17

Corroded fuse box and blown fuses

Accepted Answer

Random electrical failures, wipers, indicators, lights, ignition. The fuse box corrodes, connections get crusty, fuses blow because circuits are overloaded or shorted. Pull the fuse box, clean all contacts with contact cleaner and a wire brush. Replace dodgy fuses (use the correct rating, not a nail). Upgrade to a modern blade fuse box if you're rewiring.

Question 18

Faulty ignition switch

Accepted Answer

Key won't turn, no crank, intermittent starting, dash lights flicker. The ignition switch wears out or corrodes internally. Contacts burn, springs break. Replace the ignition switch. They're available. Takes an hour. While you're there, check the wiring to the switch, it's often corroded or melted.

Question 19

M40/M41 overdrive failure

Accepted Answer

Overdrive won't engage, kicks out under load, makes a grinding or whining noise, leaks oil. The M40 and M41 overdrives are reliable if serviced, but most haven't been. Clutch cone wear, solenoid failure, low oil, incorrect oil (ATF, not gear oil), and internal wear are common. Check the oil level first, it should be filled with ATF (Dexron III). Top up and try again. If the solenoid isn't clicking, test it (12V supply). If it still won't engage, the clutch cone or internal parts are worn, gearbox out, strip, rebuild. Specialist shops can rebuild these, or you can do it yourself with patience and a workshop manual. Budget $800-1500 for a professional rebuild.

Question 20

Worn synchros (manual gearbox)

Accepted Answer

Gears crunch going into second, reverse grinds, hard to select gears when cold. The synchros wear out, especially second gear. Abuse (clutchless shifts, forcing it into gear) accelerates this. Pull the gearbox, strip it, replace the synchro rings. It's a gearbox rebuild, not a quick job. Budget $1000-2000 for a professional rebuild, or do it yourself if you're confident. Upgraded brass synchros are available.

Question 21

Propshaft centre bearing failure

Accepted Answer

Vibration at speed, rumbling or droning noise, clunking when taking up drive. The centre bearing wears out or the rubber mount collapses. It's exposed to the elements under the car and takes a hammering. Replace the centre bearing and mount. They're available and not expensive. Drop the propshaft, swap the bearing, refit. Takes a couple of hours.

Question 22

Differential whine and backlash

Accepted Answer

Whining noise from the rear axle, clunking when changing direction (forward to reverse), vibration. Diff bearings wear, crown wheel and pinion wear, backlash increases. Low oil or incorrect oil (use 80W-90 EP) accelerates wear. Check the oil level first. Top up with the correct grade. If it's still noisy, the diff needs a rebuild, bearings, seals, possibly a crown wheel and pinion set. Budget $800-1500 for a rebuild.

Question 23

Worn front trunnions and kingpins

Accepted Answer

Clonking over bumps, vague steering, uneven tyre wear, play in the front wheels. The P1800 uses trunnions (kingpins) and bushes, not ball joints. They wear, especially if greasing has been neglected. The design is agricultural but durable if maintained. Jack up the front, check for play by rocking the wheels. If there's movement, the trunnions need replacing. It's a big job, press out the old ones, fit new bushes and kingpins, ream to size. Most people take it to a specialist. Budget $500-1000 including parts and labour.

Question 24

Sagging or broken front springs

Accepted Answer

Car sits low at the front, nose-dives under braking, poor ride quality, uneven tyre wear. Springs fatigue and sag over decades. Rust weakens them. Replace the front springs. Uprated sports springs are available if you want a firmer ride. Takes a few hours with spring compressors (hire them, don't bodge it).

Question 25

Rear leaf spring wear and broken leaves

Accepted Answer

Sagging rear end, harsh ride, clonking over bumps, uneven tyre wear. Leaf springs lose their tension, leaves crack or break, bushes perish. Rust is the main culprit. Pull the springs, have them re-arced or replace them. Poly bushes are a worthwhile upgrade. Takes a day if you're doing both sides.

Question 26

Steering box wear and leaks

Accepted Answer

Vague steering, play at the wheel, leaking oil from the steering box. The worm and sector gear wear, seals fail. Low oil or neglect accelerate wear. Adjust the steering box first, there's a screw on top to take up slack. If it's leaking or adjustment doesn't help, rebuild or replace the box. Reconditioned boxes are available. Takes a few hours to swap.

Question 27

Worn tie rod ends and track rod ends

Accepted Answer

Clonking, vague steering, uneven tyre wear, play in the steering. Ball joints in the tie rod ends wear out. They're exposed to the elements and take a hammering. Jack up the front, check for play by rocking the wheels. Replace worn ends, they're cheap and easy to swap. Get the tracking checked afterwards.

Question 28

Master cylinder failure

Accepted Answer

P1800 / P1800ES

P1800 / P1800ES known problems