How to Find the Poppet Valve on a 150 Mariner Outboard

When you replace one of the thermostats on your 150-horsepower Mariner outboard, you should also replace the poppet valve. The in-an-out replacement procedure requires only that you locate the poppet valve cover on the motor's powerhead and remove it, carefully. Locating the poppet valve cover requires the most basic knowledge of your boat -- that the starboard side of the motor is the right side of the motor, as you face forward in the boat.

Instructions

1. Press the top cowling release on the rear of the top cowling. Lift the cowling from the motor.

2. Move to the starboard side of the motor.

3. Locate the cover on the lower, starboard side of the powerhead that is secured by two 1/4-inch hex-head bolts. On carbureted or electronically fuel injected motors, the cover is round. On Opti-Max models, the cover is roughly oval. The poppet valve is located under the cover.

Tips & Warnings

• Exercise caution when removing the poppet valve cover. Beneath the cover, there's a spring-loaded diaphragm. Remove the cover slowly to ease tension on the spring.

References

• "Mariner Outboards Repair Manual, 3- , 4- and 6-Cylinder Motors, 1977-1989"; Seloc Marine; 1997
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