* Rod knock: This is a serious and expensive problem. It indicates damage to the connecting rods in the engine, likely caused by a lack of lubrication or bearing wear. This is characterized by a sharp, rhythmic knocking that increases with engine speed.
* Main bearing knock: Similar to rod knock, but involves damage to the bearings supporting the crankshaft. The sound might be more of a deeper thudding than a sharp knock.
* Wrist pin knock: This involves the piston pins, which connect the pistons to the connecting rods. The knock would likely be a high-pitched metallic sound.
* Knock sensor issue (less likely): While a knock sensor detects detonation (pre-ignition), a faulty sensor *itself* shouldn't cause a knocking sound. However, if the sensor is malfunctioning and not reporting detonation, the engine's computer may not adjust fuel delivery, potentially leading to engine damage which *could* manifest as a knocking sound.
* Exhaust system leak: A leak in the exhaust system can create a knocking or rattling sound, particularly when the engine is under load. This is usually more of a metallic clang than a deep mechanical knock.
* Loose heat shield: A heat shield that has come loose can rattle against components of the exhaust system or engine, creating a knocking noise. This is typically easy to diagnose visually.
What to do:
1. Do NOT continue driving the car: Driving with a serious internal engine problem like rod knock can cause catastrophic engine failure. The longer you drive it, the more expensive the repair will be.
2. Have a mechanic diagnose the problem: A qualified mechanic can listen to the engine, perform a compression test, and potentially other diagnostic tests to pinpoint the source of the knocking sound. This is essential to determine the extent of the damage and the necessary repairs.
3. Consider the age and condition of the vehicle: A major engine repair on a 1997 vehicle might cost more than the car is worth. A thorough assessment from a mechanic will help you make an informed decision about repair versus replacement.
The knocking sound is a serious indication of potential engine trouble. Get it checked out immediately to avoid further damage and costly repairs.
