In diagnosing overhaul issues, what is the typical test sequence?

In diagnosing overhaul issues, what is the typical test sequence?

• A. Leak-down test first, then compression test.
• B. Compression test first, followed by leak-down test.
• C. Visual inspection only.
• D. Pressure test on oil system.

Answer: (B)

The test sequence focuses on quickly assessing overall cylinder health and then pinpointing the exact source of any problem. Starting with a compression test gives a fast, simple snapshot of each cylinder’s ability to build pressure during the sealing portion of the cycle. It establishes a baseline across all cylinders and can reveal a problem area without disassembling anything. If a cylinder shows low compression, you then use a leak-down test to locate where the loss is coming from and how severe it is. The leak-down test pressurizes the cylinder and helps you distinguish between leaking past a valve, past piston rings, or through the head gasket by listening for where the air escapes and by observing the rate of leakage. This two-step approach is efficient: you first measure overall cylinder health, then drill down to the exact cause, which guides repair decisions. Visual inspection alone can miss internal issues and won’t quantify cylinder performance or localize leaks. A pressure test on the oil system checks a different subsystem and doesn’t address combustion-chamber sealing or valve/piston integrity, so it isn’t part of the typical sequence for diagnosing overhaul issues.

The test sequence focuses on quickly assessing overall cylinder health and then pinpointing the exact source of any problem. Starting with a compression test gives a fast, simple snapshot of each cylinder’s ability to build pressure during the sealing portion of the cycle. It establishes a baseline across all cylinders and can reveal a problem area without disassembling anything. If a cylinder shows low compression, you then use a leak-down test to locate where the loss is coming from and how severe it is. The leak-down test pressurizes the cylinder and helps you distinguish between leaking past a valve, past piston rings, or through the head gasket by listening for where the air escapes and by observing the rate of leakage. This two-step approach is efficient: you first measure overall cylinder health, then drill down to the exact cause, which guides repair decisions.

Visual inspection alone can miss internal issues and won’t quantify cylinder performance or localize leaks. A pressure test on the oil system checks a different subsystem and doesn’t address combustion-chamber sealing or valve/piston integrity, so it isn’t part of the typical sequence for diagnosing overhaul issues.