* Head Gasket Leak: This is a major problem. A blown or leaking head gasket allows coolant to mix with the engine oil (resulting in milky oil) or enter the combustion chamber (creating white/greyish smoke). This is a common cause of overheating and white smoke.
* Cracked Cylinder Head or Block: Similar to a head gasket leak, cracks in the engine block or cylinder head can allow coolant to leak into the combustion chamber.
* Burning Oil: Blue or bluish-grey smoke usually indicates that the engine is burning oil. This could be due to worn piston rings, valve stem seals, or a problem with the turbocharger (if equipped).
* Coolant Leak Elsewhere: Even with a new top hose, there could be other coolant leaks in the system – a leak in the lower hose, radiator, water pump, thermostat housing, or even a small crack in the radiator itself.
* Other Issues: Less common causes include:
* Clogged catalytic converter: Can cause white smoke, but usually accompanied by other symptoms like decreased power.
* Transmission fluid leak: Can sometimes cause smoke, depending on the severity and location of the leak.
What to do next:
1. Check the coolant level: Is it still dropping? This strongly suggests a leak somewhere in the cooling system.
2. Inspect the engine closely: Look for any visible signs of coolant leaks – wet spots, white residue, or steam.
3. Check the oil: Is it milky or discolored? This points to a head gasket leak or crack.
4. Check the exhaust: The color of the smoke (white, blue, black) will give clues to the source of the problem.
5. Professional Diagnosis: If you can't identify the problem yourself, take your vehicle to a qualified mechanic for a proper diagnosis and repair. Ignoring engine smoke can lead to catastrophic engine failure.
Replacing a hose is a relatively simple repair. The persistence of smoke indicates a much more serious underlying issue requiring professional attention to prevent significant engine damage.
