What is the role of Plastigauge in engine assembly?

Plastigauge is a specialized tool used in engine assembly primarily for measuring bearing clearances. It consists of a small strip of plastic that is placed between two mating surfaces, such as a bearing and a crankshaft journal. When the engine is assembled and the parts are tightened down, the Plastigauge deforms based on the amount of space between the two surfaces.

After assembly, you can remove the Plastigauge and measure the width of the flattened strip with a scale that comes with it, which correlates to the clearance between the bearing and journal. This method provides an accurate way to determine if the clearance falls within the manufacturer's specified tolerances, which is crucial for proper engine operation. If the clearance is too tight or too loose, it can lead to engine failure, making the use of Plastigauge essential during engine rebuilding or assembly.

Other choices such as sealing leaks, lubricating parts, or testing oil pressure are unrelated to the specific function of Plastigauge, as it solely focuses on measuring clearance rather than performing these other roles in engine assembly.