Starting a classic car after winter storage

Many owners start a laid-up car every few weeks and let it run for a few minutes. Our winter lay-up guide explains why the weight of specialist advice is against this. In short:

• Condensation. Burning petrol produces water. In a cold engine and exhaust it condenses instead of being driven off, and a few minutes of idling never makes things hot enough to clear it. Footman James warns that this leaves moisture in the engine that can cause corrosion and wear, and condensation in the exhaust.
• Fuel in the oil. A lubricant specialist quoted by ClassicCars.com warned that starting a cold engine briefly gives fuel dilution, blow-by and moisture in the crankcase, and Millers Oils notes that fuel dilution in lightly used cars promotes oil oxidation and degradation.

The same applies in spring: once the engine is running, drive the car gently until it is fully warm rather than leaving it idling.

Work through these with the engine off. Most take a minute each. The spring checklist puts them on one sheet.

Blockers and the reminder list

Take out every plug, bung and cloth you fitted at lay-up: exhaust, air intake, and anything under the wipers. Check each one off against the note you left on the steering wheel. Starting with the exhaust or intake blocked can damage the engine.

Mice

Look for droppings, nesting material and chewed wiring in the engine bay, the boot and under the dashboard. Lift the air filter lid and check the filter and its housing. Smell the cabin. Rodent damage to wiring or fuel pipes must be put right before the car is started, because a chewed wire can short and a chewed fuel pipe can leak onto a hot engine. See mice and rats.

Leaks

Look under the car for fresh drips and stains: engine oil (brown or black), coolant (often green, blue or orange, sweet-smelling), brake fluid (clear to amber) or petrol (thin, with an unmistakable smell). A small weep may be normal for that car; a new puddle is not.

Fuel smell

If the garage smells of petrol, ventilate it and do not start the car or use anything that could spark until you have found the leak; Hagerty UK names perished fuel hose as a common cause of engine bay fires. If the car was laid up with old or E10 fuel, decide now whether to top up with fresh fuel or drain and replace it, as set out in the winter lay-up guide.

Oil and coolant

Check the engine oil level on the dipstick with the car level. A level that has risen, or oil that looks milky or smells of petrol, needs investigating before the engine runs. Check the coolant level with the engine cold, and check the hoses for splits and soft spots.

Battery

Charge the battery fully, or refit it, connecting the correct terminal to earth (many older British cars are positive earth) and fitting the earthed terminal last, as the HSE advises. Battery maker VARTA advises recharging a stored battery when it reads 12.5 volts or less. A battery that will not hold a charge is likely to be failing, and a slow-turning engine is harder to start.

Tyres

Set the pressures back to the normal figures if you raised them for storage, and look for cracks, bulges and flat spots. A tyre that has lost a lot of pressure over the winter may have a slow puncture or a leaking valve.

Brakes and handbrake

Press the brake pedal. It should be firm and high, and should not sink slowly under steady pressure. A pedal that sinks, or a fluid level that has dropped, means a leak: do not drive the car. Check the brake fluid level and its age: it absorbs water over time, so change it if it is due. Make sure the handbrake releases fully, and that the car rolls freely if it is safe to push it a short way.

Paperwork

If the car has a SORN, it must be taxed and insured before it goes on the road. Historic vehicles still have to be taxed, even though the tax is free. See storing a classic car for tax, SORN and insurance.

Over a winter, petrol can evaporate from the carburettor float chambers and the fuel lines can partly drain. An electric fuel pump will refill them when the ignition is switched on. Give it time to fill them before you start. If the pump keeps running and does not stop, switch the ignition off and look for a fuel leak.

A mechanical fuel pump only works while the engine turns, and at cranking speed it pumps slowly, so a car with empty float chambers can take a long time to start. Long cranking drains the battery and heats the starter motor. Some ways to help:

• Use the hand priming lever if your pump has one, as your workshop manual describes; it fills the float chambers without cranking.
• Turn the engine in short bursts, with pauses between, rather than one long crank.
• Do not pour petrol into the carburettor or the air intake.

If the float chambers still will not fill, the cause may be a blocked filter, a perished pump diaphragm or a blocked pickup in the tank. That is a job to diagnose before starting, not by cranking harder.

With the doors open

Open the garage doors fully before you start the engine, and keep the car's tailpipe pointing out if possible. The NHS lists running an engine in an enclosed space such as a garage as a cause of carbon monoxide poisoning. Have a fire extinguisher within reach (see fire safety in the garage).

Cranking

Turn the engine in short bursts with a pause between attempts, and follow your car's handbook on how long. Limits vary: as an example, a current Kia handbook says not to run the starter for more than ten seconds, and to wait 5 to 10 seconds before trying again.

Some specialists recommend turning a long-stored engine over with the ignition disabled to build oil pressure before it fires. That is part of recommissioning after years off the road. After a single winter, with fresh oil put in before the lay-up, it is not usually needed.

Choke and first start on a carburettor car

Use the choke as your handbook describes. Systems differ between carburettors, and some cars have automatic chokes. General points:

• Use as much choke as the engine needs to start, then push it in progressively as it warms, until it runs evenly without it. One SU carburettor specialist advises using the choke only when the engine is very cold, pulling it fully out, then pushing it in slowly as the engine starts to run smoothly.
• Do not leave the choke out for longer than needed. Running rich washes oil from the bores and dilutes the sump oil.
• Pumping the accelerator squirts extra fuel into the carburettor on types with an accelerator pump; SU and Stromberg carburettors have none. Follow your handbook on whether to press the accelerator when starting.
• If the engine floods (a strong smell of petrol and the engine will not catch), stop cranking, ventilate the garage and follow your handbook's procedure for clearing it.

Oil pressure

Watch the oil pressure light or gauge as soon as the engine fires. The light should go out, or the gauge should show pressure. If it does not, switch off at once. The AA warns that continuing to drive with the oil pressure light on can lead to catastrophic engine damage, and that a matter of seconds can separate a simple top-up from a badly damaged engine.

Smoke

A cloud of white vapour from the exhaust on a cold morning is usually condensation: water that has collected in the exhaust over the winter. It should clear as the exhaust warms. Smoke that does not clear is a sign of a fault:

Listen and look

With the engine running, listen for knocking, rattling or squealing belts, and look again for leaks under the car, now that there is pressure in the oil, fuel and cooling systems. Check the charging light goes out or the ammeter shows a charge as the revs rise.

Once the engine is running steadily and you have checked for leaks, drive off gently, keeping the revs moderate until the temperature gauge reaches normal. That warms the engine faster than idling and is better for the oil.

Watch the temperature gauge on the way. If it rises above normal, the cooling system may have an airlock, a sticking thermostat or a leak: stop and let it cool before investigating. Never open the radiator or expansion tank cap on a hot engine.

Test the brakes before the road

Brake discs and drums rust on the surface while a car stands, and brakes can stick. Brembo, the brake manufacturer, says surface rust is usually cleaned off in normal use, but that a car that has stood should be driven with extra care at first, testing the brakes gently and expecting some noise for the first few miles. Before you leave the drive:

• roll forward and backward slowly, pressing the brake each time, and listen for grinding or a brake that stays on;
• on the first quiet stretch of road, brake gently a few times to clean the discs;
• feel for the car pulling to one side, which suggests a sticking brake or one working poorly.

If noise continues, the brakes judder, or a wheel stays locked, do not carry on. After a short drive, carefully hold your hand near each wheel without touching it: one that is much hotter than the others suggests a brake that is binding.

Keep it short

Make the first drive short and gentle, close to home, in daylight and dry weather if possible. Check the lights, indicators, wipers and horn first, and carry your phone and breakdown cover details.

Afterwards

When you are back, look under the car again for leaks, check the oil and coolant levels when cool, and look over the engine bay for anything that has come loose. A Toyota master technician advising classic owners in 2022 recommended repeating the checks after the first proper drive, because heat, expansion and vibration can show problems that stayed hidden while the car was parked.

Switch off, and get help from a specialist or your breakdown service rather than carrying on, if:

• the oil pressure light stays on or the gauge shows no pressure;
• you see or smell a fuel leak, or smoke from under the bonnet or dashboard;
• the brake pedal sinks, feels soft or goes to the floor, or a brake stays on;
• the engine overheats;
• there is a new knock or heavy rattle from the engine;
• smoke from the exhaust does not clear once the engine is warm;
• a wheel stays locked, or the car pulls sharply when braking.

Do not keep cranking an engine that will not start. A car that will not start after a winter usually has a simple fault, such as no fuel reaching the carburettor or no spark, that is better found than forced.

Before the season starts, work through the spring checklist. When the season ends, the winter lay-up guide and printable checklist will make next spring easier.