Here's a breakdown of the likely culprits:
* Head Gasket Failure: This is a serious issue. A blown head gasket allows coolant to leak into the cylinders. When the engine starts, this coolant is burned, producing white smoke. The shaking is likely due to the engine misfiring from the coolant in the cylinders and potentially from low compression in affected cylinders.
* Cracked Cylinder Head: Similar to a blown head gasket, a crack in the cylinder head can also allow coolant to enter the combustion chamber, causing white smoke and engine shaking.
* Coolant Leak into the Engine Oil: If coolant is leaking into the oil, you might also notice milky, white or brown oil (mayonnaise-like consistency) on the dipstick. This is a serious problem, requiring urgent attention. The shaking could be due to the compromised lubrication from the coolant in the oil.
* Less Likely (but possible): A severely clogged catalytic converter could cause some shaking, but white smoke is less characteristic of a catalytic converter problem. A failing valve cover gasket could also leak oil, burning and causing some smoke but usually less substantial.
What you should NOT do:
* Continue driving the car: Driving with a head gasket or cylinder head problem can cause catastrophic engine damage.
What you SHOULD do:
* Stop driving the car immediately. Further damage will cost significantly more to repair.
* Have the car towed to a qualified mechanic. They can properly diagnose the problem and provide an accurate repair estimate.
* Do NOT attempt to top off the coolant. This might mask the problem and make diagnosing the root cause more difficult.
The white smoke and shaking are strong indicators of a serious engine problem that requires professional attention. Ignoring it could lead to extensive and costly repairs or even a complete engine replacement. Get it checked out as soon as possible.
