* Coolant Leak into Cylinders: The most likely culprit is a crack in the engine block, head gasket failure, or a cracked cylinder head. When the engine is idling, the coolant can seep into the cylinders. When you accelerate, the increased engine pressure forces this coolant (mostly water) out through the exhaust as white smoke. This is a costly repair, potentially involving a head gasket replacement, head repair, or even a block replacement depending on the extent of the damage.
* Less Likely, but Possible Causes:
* Blown Head Gasket (partially): A small leak might only manifest under pressure.
* Cracked Engine Block (minor): A hairline fracture might only leak under certain conditions.
* Worn Valve Stem Seals: Less likely to cause *large* amounts of white smoke, but could contribute to some. This is usually accompanied by blue smoke (oil burning) rather than primarily white.
Why it's costly:
Repairing these issues requires significant labor. The engine may need to be partially or completely disassembled, requiring specialized tools and expertise. Parts like head gaskets, cylinder heads, or even an engine block are expensive components.
What to do:
1. Don't drive the car: Continuing to drive will likely worsen the damage and could lead to a catastrophic engine failure.
2. Check the coolant level: See if it's low. If it is, this strongly supports a leak into the engine.
3. Have a mechanic inspect it immediately: A qualified mechanic can properly diagnose the problem using compression tests, leak-down tests, and a visual inspection. This is crucial to determine the extent of the damage and the best course of action.
Cost Estimate: Expect to pay several hundred to potentially thousands of dollars for repairs, depending on the severity of the problem and the location of the damage. A head gasket replacement alone can be a substantial expense.
Ignoring this problem will likely result in much more expensive repairs down the line, or even a need for engine replacement. Get it checked by a professional ASAP.
