* Low Coolant: White smoke, especially if it's thick and smells sweet, strongly suggests coolant is leaking into the cylinders. This could be due to a blown head gasket, cracked cylinder head, or a warped cylinder head. The shaking could be a result of the engine misfiring due to the coolant in the cylinders.
* Valve Cover Gasket Leak: A less serious (but still significant) leak is a failing valve cover gasket. This will leak oil, which *can* appear as a lighter, less dense white smoke, particularly on startup. However, shaking is less likely to be a direct result of just a valve cover leak.
* Crankshaft Position Sensor (CKP) or other Sensor Issues: A faulty CKP sensor, mass airflow sensor (MAF), or other engine sensors can cause misfires, leading to shaking. White smoke isn't directly related to these sensor issues, unless they're indirectly causing a related problem like overheating.
* Worn Engine Mounts: Worn engine mounts can cause vibrations and shaking, felt throughout the car. This won't produce smoke.
* Transmission Problems: Although less likely to cause white smoke, transmission issues can lead to shaking, particularly if the transmission is slipping or failing.
To diagnose the problem:
1. Check the coolant level: Is it low? If so, this is a major red flag pointing to a head gasket or other coolant leak.
2. Inspect for leaks: Look carefully around the engine for any visible leaks of coolant or oil. Pay close attention to the head gasket area, valve covers, and hoses.
3. Check the oil: Is the oil milky or frothy (indicative of coolant mixing with oil)? This confirms a coolant leak into the engine.
4. Observe the smoke: Is it a constant cloud, or does it only appear on startup? The consistency and smell (sweet = coolant) will provide clues.
5. Listen to the engine: Are there any unusual noises like knocking or ticking?
Important Note: Driving a car with these symptoms could cause serious engine damage. It's best to have a mechanic diagnose the issue as soon as possible. Ignoring it could lead to a costly engine rebuild or replacement.
