When rebuilding an engine with a camshaft located in the cylinder block, what symptom would indicate worn or missing camshaft bearings?

When rebuilding an engine with a camshaft located in the cylinder block, what symptom would indicate worn or missing camshaft bearings?

• A. Noisy valve operation
• B. Lower oil pressure reading
• C. Noisy during high engine loads
• D. Premature camshaft gear

Answer: (B)

When the camshaft is supported by bearings in the block, those bearings must maintain a tight, lubricated clearance to keep oil pressure up. If the cam bearings are worn or missing, that clearance increases, so oil can leak past more easily and the oil pressure in the system drops. The oil pump still pushes oil, but it can’t build or maintain the same pressure due to the greater flow path and leakage, so you’d observe a lower oil pressure reading. Other symptoms listed are less directly tied to cam bearing condition. Noisy valve operation usually points to lifters, cams, or valve-train components rather than the bearings themselves. Noise during high engine loads or a premature camshaft gear would suggest different issues like timing or drive train problems. The clearest indicator of worn or missing camshaft bearings is a drop in oil pressure observed on the gauge.

When the camshaft is supported by bearings in the block, those bearings must maintain a tight, lubricated clearance to keep oil pressure up. If the cam bearings are worn or missing, that clearance increases, so oil can leak past more easily and the oil pressure in the system drops. The oil pump still pushes oil, but it can’t build or maintain the same pressure due to the greater flow path and leakage, so you’d observe a lower oil pressure reading.

Other symptoms listed are less directly tied to cam bearing condition. Noisy valve operation usually points to lifters, cams, or valve-train components rather than the bearings themselves. Noise during high engine loads or a premature camshaft gear would suggest different issues like timing or drive train problems. The clearest indicator of worn or missing camshaft bearings is a drop in oil pressure observed on the gauge.