Corrosion Control Anode; Spark Plug Inspection And Replacement - Mercury 150 EFI Service Manual

MAINTENANCE

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 and Replacement

Inspect spark plugs at the recommended intervals.
Avoid serious injury or death from fire or explosion caused by damaged spark
plug boots. Damaged spark plug boots can emit sparks. Sparks can ignite fuel
vapors under the engine cowl. To avoid damaging spark plug boots, do not use
any sharp object or metal tool such as pliers, screwdriver, etc. to remove spark
plug boots.
1. Remove the spark plug leads by twisting the rubber boots slightly and pulling off.
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.
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 Nm).
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a
b
WARNING
90-883728 JULY 2001