What are two ways of pre-oiling an engine?

What are two ways of pre-oiling an engine?

• A. Before spark plugs are installed and after the oil tank is filled, turn the engine over with the starter until oil runs out of the fitting to which the oil pressure gauge connects.
• B. Use a pre-oiler tank. Air pressure forces oil through all of the passages until some of it flows from the oil pressure gauge fitting.
• C. Both of the above.
• D. None of the above.

Answer: (C)

Priming the lubrication system before the first start is essential to prevent wear as the engine rotates without oil in the passages. One approach is to remove the spark plugs, fill the oil tank, and use the starter to rotate the engine until oil appears at the fitting for the oil-pressure gauge. This confirms that oil has reached the main passages and bearings, priming the system so that when the engine is started, oil pressure comes up quickly and components are protected from dry starts. The spark plugs are removed to eliminate compression and make cranking easier while the passages fill. The other approach uses a pre-oiler tank connected to the engine, with air pressure pushing oil through all the passages until some oil exits at the oil-pressure gauge fitting. This externally supplied flow reliably fills the galleries and bearing surfaces, achieving the same aim of ensuring lubrication before normal operation begins. Both methods achieve the same goal—pre-oiling the engine to prevent startup wear—so selecting either technique is appropriate, depending on what equipment is available and the engine’s procedures.

Priming the lubrication system before the first start is essential to prevent wear as the engine rotates without oil in the passages.

One approach is to remove the spark plugs, fill the oil tank, and use the starter to rotate the engine until oil appears at the fitting for the oil-pressure gauge. This confirms that oil has reached the main passages and bearings, priming the system so that when the engine is started, oil pressure comes up quickly and components are protected from dry starts. The spark plugs are removed to eliminate compression and make cranking easier while the passages fill.

The other approach uses a pre-oiler tank connected to the engine, with air pressure pushing oil through all the passages until some oil exits at the oil-pressure gauge fitting. This externally supplied flow reliably fills the galleries and bearing surfaces, achieving the same aim of ensuring lubrication before normal operation begins.

Both methods achieve the same goal—pre-oiling the engine to prevent startup wear—so selecting either technique is appropriate, depending on what equipment is available and the engine’s procedures.