Corrosion Control Anode; Spark Plug Inspection - Mercury Optimax 115 Service Manual

Corrosion Control Anode

The gear case has two corrosion control anodes (a). Another anode (b) is installed on the
bottom of the transom bracket assembly. An anode helps protect the outboard against
galvanic corrosion by sacrificing its metal to be slowly eroded instead of the outboard
metals.
Each anode requires periodic inspection especially in salt water which will accelerate the
erosion. To maintain this corrosion protection, always replace the anode before it is com-
pletely eroded. Never paint or apply a protective coating on the anode as this will reduce
effectiveness of the anode.

Spark Plug Inspection

Inspect spark plugs at the recommended intervals.
1. Remove the spark plug leads by twisting the rubber boots slightly and pull off. Inspect
spark plug boots and replace if cracked.
2. Remove the spark plugs to inspect and clean. Replace spark plug if electrode is worn
or the insulator is rough, cracked, broken, blistered or fouled.
3. Set the spark plug gap. See Specification Chart in General Information Section.
4. Before reinstalling spark plugs, clean away dirt on the spark plug seats. Install plugs
finger tight, and tighten 1/4 turn or torque to 20 lb. ft. (27 N·m).
90-855347R1 JANUARY 1999
a
b
MAINTENANCE
Page 1B-7