- Oil leakage: If there's a leak in the oil pan, oil filter, or valve cover gasket, oil can drip onto the exhaust manifold and burn, producing smoke.
- Coolant leak: A leak in the cooling system, such as a cracked radiator or a faulty water pump, can cause coolant to leak onto the exhaust manifold and produce steam, which can appear like smoke.
- Faulty fuel injector: A faulty fuel injector can cause too much fuel to be injected into the engine, resulting in incomplete combustion and the production of black or gray smoke.
- Worn piston rings: Worn or damaged piston rings can allow oil to seep into the combustion chamber, leading to blue smoke from the exhaust.
Additionally, if the car has been sitting for a long time and the engine is cold, it's normal for some steam or condensation to be produced from the exhaust, which can be mistaken for smoke.
