What is a potential indicator of a hydraulic lifter issue in an engine?

A potential indicator of a hydraulic lifter issue in an engine is the presence of no clearance in the valve-operating mechanism. Hydraulic lifters are designed to maintain zero clearance between the lifter and the valve actuator components, ensuring proper operation. However, if the lifter malfunctions, it can lead to excessive or insufficient clearance, which can affect the engine's performance.

When there is no clearance and the hydraulic lifters are not functioning properly due to internal wear, lack of oil flow, or contamination, it can result in valve train noise, erratic engine performance, and potentially engine damage over time. Therefore, observing that there is no clearance in the valve-operating mechanism can indeed suggest a problem with the hydraulic lifters.

In contrast, excessive oil pressure might indicate issues related to oil supply but does not directly point to hydraulic lifter problems. High exhaust temperature typically indicates an issue with the combustion process, such as improper air-fuel mixture or exhaust restrictions. Increased RPM could suggest engine load variations or operational changes but does not specifically indicate hydraulic lifter issues.