Which engine servicing operation generally requires engine pre-oiling prior to starting the engine?

Which engine servicing operation generally requires engine pre-oiling prior to starting the engine?

• A. Engine overhaul
• B. Routine maintenance
• C. Engine installation
• D. Calibration

Answer: (C)

Getting oil to every bearing and moving part before the first start is key to protecting the engine from wear during initial startup. When an engine has been removed and then reinstalled, the lubrication system can be dry or partially drained, and oil has not yet filled all passages. Pre-oiling forces oil through the galleries and bearings so that, when the crank is first turned, oil pressure is established immediately and metal-to-metal contact is avoided. This makes engine installation the operation where pre-oiling is most commonly required. Routine maintenance mainly involves checking and topping up oil and fluids, not priming the entire oil system before startup. An overhaul or calibration can involve priming as part of the reassembly or setup, but the situation that most clearly needs pre-oiling before starting is installing a rebuilt or new engine where the oil system has been drained or unprimed.

Getting oil to every bearing and moving part before the first start is key to protecting the engine from wear during initial startup. When an engine has been removed and then reinstalled, the lubrication system can be dry or partially drained, and oil has not yet filled all passages. Pre-oiling forces oil through the galleries and bearings so that, when the crank is first turned, oil pressure is established immediately and metal-to-metal contact is avoided. This makes engine installation the operation where pre-oiling is most commonly required.

Routine maintenance mainly involves checking and topping up oil and fluids, not priming the entire oil system before startup. An overhaul or calibration can involve priming as part of the reassembly or setup, but the situation that most clearly needs pre-oiling before starting is installing a rebuilt or new engine where the oil system has been drained or unprimed.