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Mercruiser 4-Cycle Oil Priming Procedure

Manufacturer Mercury Marine
Engine Type Outboard
Repair Time Less than 30 mins
Repair Difficulty Easy
Sections 2


  1. Method A (Preferred)
  2. Method B (Optional)

: All Mercury remanufactured 4-cycle engines are temporarily fit with electrical systems, fresh water, and premium fuel to perform a series of "Hot-Test" validations for quality control purposes. Thereafter, the engine oil drains back into the pan and looses its lubrication value from the valve-train and cylinder walls. We require the installer to perform an "Oil Priming" procedure prior to the engines initial start-up to reduce the potential for premature bearing failures.

: There are two different methods to prime an engine prior to ignition. Either can be used. Method A utilizes a standard GM engine-oil Priming Tool (purchased locally). Method B is performed with a Remote-Starter-Switch (tool # 91-52024A 1).

Method A (Preferred)

  1. Fill engine crankcase to proper level with recommended marine engine oil.

  2. Remove the complete distributor assembly.

  3. Install the oil "Priming-Tool" into distributor bore and onto the oil pump shaft.

  4. Rotate the oil pump with an electric drill for approximately 2-minutes, or until oil pressure registers on an oil pressure gauge.

  5. Remove the priming tool and reinstall the distributor according to instructions outlined in a MerCruiser Service Manual.

Method B (Optional)

  1. Fill engine crankcase to proper level with recommended marine engine oil.

  2. Remove all spark plugs.

  3. Disconnect the high-energy wire from the distributor and connect it to a good ground.

  4. Leave ignition key in the "OFF" Dosition.

  5. Connect one end of the "Remote-Starter-Switch" to the 12-Volt red oositive battery cable terminal and the other end to the smaller (yellow-red) terminal on the starter motor.

If you opt to use the ignition switch instead of the remote-starter, disconnect the PUR wire from the coil before turning the key. Cover the PUR wire with tape to avoid a possible ground condition.

  1. Crank the engine over for approximately 15-18 seconds. Let the starter motor cool down for i-minute before cycling again. Repeat this process more times.

  2. Remove the Remote-Starter-Switch, or reconnect the PUR wire to the ignition coil.

  3. Install the spark plugs and plug wires.

  4. Start the engine with a good supply of cool water.

52024A1 - Mercury Marine Switch Assembly