Here's why and what might be wrong:
* Overheating damage: Seven miles of driving while severely overheated likely warped the cylinder head or cracked the engine block. This leads to:
* Head gasket failure: A blown head gasket is a common result of overheating. This allows coolant to mix with oil or enter the cylinders, leading to a lack of compression and preventing the engine from starting.
* Warped cylinder head: A warped cylinder head prevents proper sealing of the combustion chamber, again resulting in loss of compression.
* Cracked engine block: In severe cases, the engine block can crack, causing coolant leaks and internal damage that prevents starting.
* Seized engine: Extreme overheating can cause parts of the engine to seize, making it impossible to turn over.
* Timing belt (less likely, but possible): While less probable than the overheating damage, the extreme heat *could* have weakened the timing belt, causing it to slip or break. This would mean the valves and pistons are not synchronized, causing significant damage and preventing starting.
* Other possibilities: Although less likely given the circumstances, the overheating could have damaged other components such as the ignition system or fuel pump.
What to do:
1. Do NOT attempt to start the car again. Continuing to try will likely cause further, irreparable damage.
2. Cool down completely: Let the engine cool completely before attempting any further diagnosis. This could take several hours.
3. Check the coolant level: The radiator and overflow tank will be low or empty. Look for signs of coolant leakage.
4. Check the oil: Look for milky or frothy oil, indicating coolant contamination (head gasket failure).
5. Have it towed: Towing is essential. Attempting to diagnose and repair this yourself with only the information provided is highly risky and likely to cause more harm and cost than a professional repair.
A mechanic needs to properly diagnose the extent of the damage. The repair could range from a relatively inexpensive head gasket replacement to a complete engine rebuild or replacement, depending on the severity of the overheating damage. The cost will depend greatly on the specific problem.
