A mechanic is checking main bearing clearance with plastigage. If the plastigage flattens more at one end than the other, it would indicate:

When using plastigage to check main bearing clearance, observing that it flattens more at one end than the other suggests an issue with the bearing alignment or support. In this case, it is indicative of the possibility that the rod is bent.

A bent rod can cause uneven pressure across the bearing surface. This uneven pressure would result in one end of the plastigage flattening more than the other, reflecting that the load distribution is not uniform. Correctly installed bearings should provide an even contact surface with the crankshaft, allowing for a symmetrical flattening of the plastigage.

In contrast, while improperly installed bearings could potentially cause similar issues, they would more likely manifest as an overall lack of clearance rather than a variation in flattening across the length of the plastigage. Engine misalignment could create further issues in terms of wear and could lead to uneven contact but would typically be identified through other symptoms and checks. Lastly, using oil that is too thick would not directly cause the plastigage to behave this way; instead, it would simply affect oil flow and lubrication, leading to different operational issues.

Thus, noticing the differential flattening of plastigage points primarily to a bent rod, as this directly affects how