136. The diesel engine component labeled «5», shown in the illustration is known as the __________

The piston thrust washer (D) is correct; label 5 indicates a washer that controls piston side thrust and axial movement near the crankshaft. This component manages side thrust loads, unlike the piston crown, connecting rod end assembly, or a heat sink space. Its location near the crankpin eliminates options referencing the piston crown or connecting rod end assembly, and 'heat sink space' is not a recognized component name.