What does the presence of air bubbles in the radiator during a cylinder leakage test indicate?

The presence of air bubbles in the radiator during a cylinder leakage test is indicative of a head gasket leak. This test involves applying pressure to the cylinder with the intention of determining if there are leaks in the combustion chamber. When there’s a breach in the head gasket, the combustion gases can escape into the cooling system, which leads to the formation of air bubbles in the radiator.

This scenario signifies that the integrity of the head gasket is compromised, allowing exhaust gases to mix with the coolant, which can create air pockets. Additionally, a head gasket leak can result in overheating and further engine damage if not addressed promptly. It is crucial to accurately identify this issue, as resolving a head gasket leak involves significant repair work to prevent ongoing engine problems.

While the other options could indicate their own unique issues within the cooling system, they do not specifically correlate with the observation of air bubbles in the radiator during this particular test. For example, issues with the water pump or a faulty thermostat may affect coolant circulation or temperature regulation, but they would not typically cause the presence of air bubbles like a head gasket leak would. Clogged radiator passages are generally characterized by poor coolant flow or overheating, rather than directly causing bubbles in the radiator.