If all cylinders show around 110 psi during a compression test, what does this likely indicate?

When all cylinders show around 110 psi during a compression test, it often indicates a uniform issue across the engine's cylinders, and this level of compression is generally lower than what would be expected for most engines, especially those with good health. Worn piston rings can lead to reduced compression in all cylinders. When the piston rings wear, they lose their ability to create a proper seal between the piston and the cylinder wall, allowing gases to escape during the compression stroke, which results in lower pressure readings across the board.

A uniform drop in compression suggests that the issue is not localized but rather affects the overall sealing capability of the engine's sealing components. High mileage engines often experience this kind of wear and thus may show such low and even compression readings.

While faulty spark plugs, poor valve seating, and leaking head gaskets can also cause compression issues, they typically result in more erratic compression readings. For instance, faulty spark plugs usually affect only the performance of the cylinder they are in rather than contributing to low compression across all cylinders. Likewise, poor valve seating and leaking head gaskets would likely show varying compression numbers rather than an equal reduction in all cylinders. Thus, the presence of similar low readings strongly points towards the possibility of worn piston rings as the