What should short pieces of hose be used to protect when assembling an engine?

Short pieces of hose are commonly used to protect rod journals during the engine assembly process. Rod journals, which are located on the crankshaft, must remain free from scratches, dents, or other forms of damage to ensure smooth operation and longevity of the engine. When assembling parts around the rod journals, using hose as a protective barrier helps to safeguard against potential impacts or contact with tools that could lead to surface imperfections.

This practice is crucial because any damage to the rod journals can lead to serious issues like increased wear, oil leakage, or even catastrophic engine failure. By covering these critical areas with short lengths of hose, mechanics can prevent debris accumulation and provide cushioning against mechanical stresses during assembly.

The other options, while all representing important components of the engine, are not typically protected using short pieces of hose in the same way. Main bearings and cam journals can be protected using other methods or are often assembled in a manner that minimizes the risk of damage without additional protective measures. Crankshaft seals, on the other hand, are generally designed to fit precisely and are protected through their specific installation processes, rather than relying on additional protective covers like hose.