Which of the following is NOT a cause of low engine compression?

Low engine compression is primarily a result of factors that compromise the seal of the combustion chamber. Worn piston rings and damaged valves both lead to a loss of pressure during the compression stroke. Worn piston rings can result in a poor seal between the piston and cylinder wall, allowing combustion gases to escape into the crankcase. Similarly, damaged valves may either not close completely or may not seal properly, allowing gases to leak past them.

Excess oil consumption can also indicate low engine compression because it typically results from similar issues, such as worn piston rings that permit oil to enter the combustion chamber. This can lead to burning oil, which not only signifies an issue but also impacts performance.

In contrast, a properly functioning head gasket ensures that there is a tight seal between the engine block and the cylinder head, preventing any loss of compression due to leaks. If the head gasket is in good condition, it does not contribute to low compression, which is why it is not considered a cause of this issue. Understanding these distinctions is crucial for diagnosing engine performance problems accurately.