A customer’s engine represents a major investment. Regardless of whether the engine is new (a factory replacement engine), a freshly rebuilt engine, or an engine that has been stored for an extended period, it can be quickly damaged if the bearings and friction related components are not properly lubricated prior to firing the engine for the first time.
NEVER start a fresh engine without first circulating oil through the oil galleys to provide oil to the bearings and valvetrain.
Even though the engine may have been recently assembled with a quality engine assembly lube on the bearings, pre-oiling is absolutely mandatory. Rather than cranking the engine and waiting for oil pressure to build via the engine’s oil pump, pressurizing the oil circuits before ever cranking the engine will ensure lubrication that will protect the bearings and valvetrain from damage during the first rotation of the crank.
This also holds true for even a previously run engine that may have sat dormant for a long period of time. Main bearing, rod bearing, cam bearing, rocker tip and other potential valvetrain damage can be easily avoided by first pressure pre-oiling the engine before it’s started.
As we all know, engines that feature an oil pump driven by the camshaft can be pre-oiled by removing the distributor and running the oil pump with the use of an adapter and a power drill. That traditional practice works fine, assuming that you’re able to drive the oil pump without rotating the crankshaft. However, late model engines that feature a front-mounted oil pump that’s driven by the crankshaft cannot be pre-oiled in this manner. The use of a pressurized pre-oiling tank allows you to easily push pressurized oil throughout the engine’s oil circuit without the need to turn the engine’s oil pump (the LS engine is but one example). These pressure tanks are applicable to any engine, regardless of the year of manufacture or the location and design of the oil pump.
It’s all too common for some folks to assume that there’s no need to pre-oil, since they believe that the engine’s oil pump will distribute oil through the engine’s oil circuit quickly enough to protect the bearings. A common practice involves disconnecting the coil wire and cranking the engine, in order for the oil pump to build pressure. While this will eventually pull oil from the sump and deliver to the main feeds, in the process of cranking the engine (even without firing), there is no guarantee that you’ll have adequate lubrication delivered quickly enough to protect the bearings during this initial cranking period. Beyond a concern for sending oil to the main bearings, by cranking the engine, it will take even longer to send oil all the way up to the rockers.