Anyone who has built or rebuilt an engine knows — or should know — that one of the final steps before the first start-up of the new mill is to prime the oiling system. Traditionally, that is done by chucking up an oil pump priming tool into a cordless drill and running the oil pump for a few minutes until you have oil throughout the engine, and pressure at the gauge.

However, with the explosion in popularity of gerotor pumps, using a mechanical pump priming tool isn’t an option. That leaves you with only one way to properly prime the oil system: via pressure. Not a new concept by any means, the Melling MPL-201 pressure priming tool makes the job a snap.

A larger, more robust version of Melling’s MPL-101 one-gallon pressure priming tool, the external difference is immediately obvious, with the previous -101 looking like a small propane tank, While the new -201 looks like a mini pony keg, both due to its shape and its stainless steel construction.

Functionally, the -201 has a number of improvements, starting with the increased-capacity tank made from better materials. A large tank opening houses a revised pressure valve, which incorporates a standard Schrader valve to pressurize the tank with any air compressor and a 75psi blow-off valve to prevent overpressurization of the vessel.

Additionally, the MPL-201 comes with an eight-foot long chemical-resistant hose with swivel fittings at each end, as well as three common adapter fittings — including a 16mm LS adapter. These parts are critical to properly connect the pressure tank to the engine block. The flow of pressurized oil is controlled by a quarter-turn valve for easy control of the oil flow (which is very handy if you’ve forgotten to put the oil filter on… or so we’ve heard).

Besides the increased capacity over the previous model, the MPL-201 has a much-improved valve assembly, incorporating a 75psi release valve and a quarter-turn shutoff valve.