Here's a breakdown of why:
* Loss of Power & Lack of Compression: These are classic symptoms of a compromised seal between the cylinders and the oil system. A blown head gasket allows combustion pressure to escape into the cooling system (causing overheating and potentially pressure in the coolant system) or the crankcase (reducing compression and causing oil contamination). A cracked head or block has the same effect.
* Smoking from the Back (Exhaust): Burning oil is entering the combustion chamber. This is caused by the leaked oil from a failed head gasket or crack. The blueish-grey smoke is a telltale sign of burning oil.
* Smell of Burning Oil: This further confirms oil is getting into the combustion chamber and burning.
The combination of these symptoms points towards a serious mechanical issue. Do not attempt to restart the engine. Continuing to run it will cause further damage.
Possible Causes (in order of likelihood):
1. Blown Head Gasket: This is the most common culprit for these symptoms in older air-cooled engines. The gasket seals the cylinders from the oil and coolant passages. Failure leads to mixing of oil and coolant, and loss of compression.
2. Cracked Cylinder Head or Block: This is more serious and often requires a replacement head or even a rebuild/replacement of the engine. Cracks allow coolant or oil to leak into the combustion chamber. This is less common than a blown head gasket, but still a possibility.
3. Worn Piston Rings: While less likely to cause all the symptoms at once (the smoking would likely have been gradual), severely worn piston rings could contribute to the loss of compression and some oil consumption. However, the sudden nature of the failure suggests something more catastrophic.
What to do:
1. Tow the Beetle: Don't drive it! Further damage is highly probable.
2. Call a mechanic specializing in air-cooled Volkswagens: This is not a DIY job unless you have significant experience with air-cooled engine repair.
3. Prepare for a potential major repair: The cost could range from a head gasket replacement to an engine rebuild or replacement, depending on the extent of the damage.
The diagnosis requires a thorough inspection by a mechanic. They'll likely perform a compression test to confirm the lack of compression in one or more cylinders and visually inspect the head and block for cracks.
