Oiler Delete

Switching Back to PreMix - Oiler Delete

One step closer on the journey from ELPTO to M.

Most 3 cylinders were equipped with automatic oiling and had an under cowling reservoir. A common failure point for the oiler system is the check valve that prevents oil from draining into the fuel line when the motor is off. When the valve fails, it over mixes the fuel which leads to difficult and smokey starts. The check valve is easy to fix but some prefer to revert to premixing their fuel. Parts that aren't installed, can't break. Since the pull start handle occupies the same space as the reservoir fill hole, removal of the oiler is neccessary to switch a motor from ELPTO to M. Whatever the motivation, wrong or right, the following is a guide to oiler removal on a 59" Mercury 3 cylinder 40, 50 or 60 HP.

Oil Reservoir Removal

Cowling off, the reservoir is only attached with two 10mm hex head screws. Fortunately, the oil cap does a good job of holding in fluid as you lay the reservoir to the side for removal of wires and tubing.

The two bullet connectors can be disconnected and forgotten, no jumper necessary to prevent the alarm.

When you pull the black hose from the oil pump, be ready to plug the hose so you only spill a little of the blue gold.

Block Off Plate

Buy number 37 and 38.

Block Off Plate / Cover

812996 In the flesh.

Often Faulty Check Valve

Can't break if you take it off.

A standard height 1/4" drive, 5/16" socket hooked to a 1/4" impact driver turned with a 1/4" box wrench are sufficient for removal of the difficult Oil Pump screw.

SAVE THESE SCREWS. You'll need them to attach the Block Off Plate.

Oil Pump Removal

Disconnect the Oil Mixing Y from the Fuel Pump and the Fuel Feed line.
Plug the Fuel Feed line directly to the Fuel Pump.
Disconnect the Stainless Linkage from the Throttle Shaft.
Remove the two 5/16" headed screws from the Oil Pump
The screw pictured is difficult to remove.

The O-ring on the Oil Pump can be reused if it is in good shape. They are about a dollar so you might as well buy one. That said, the plastic cover will seal fine without an O-ring at all.

With the oil pump off, remove the pump shaft bushing. In order to fit, the bushing needs to come out before the pump shaft but they'll try and come out together.

The pump shaft/gear is too long to come out whole. Bolt cutters work great for safely getting it in two.

Mercury 59 inch oil pump gear removed with bolt cutters.

Back Together

With an O-Ring added to the Block Off Plate or Cover as Mercury calls it, the two 5/16" screws can be used to secure it in place.

Final Thoughts

Be sure to secure the fuel line to the fuel pump with a ziptie before reinstalling the cowling. If the check valve failed and over oiled the fuel, it's easy to go to the other side of the engine and drain the carb bowls. There will be a brass screw on the lower side of each carb on the port side of the engine. Don't forget to mix oil in with the gas in the fuel tank and clear the fuel line of the unmixed or overmixed fuel.

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