GENERAL SERVICE INFORMATION
2-39
3-/ 4-Cylinder
ANODES - INSPECTION AND TESTING
Engines are equipped with several sacrificial anodes to help protect
metal parts from the effects of galvanic corrosion (electrolysis).
Disintegration of the anodes indicates they are performing their
function. An anode must be replaced when it has been reduced to
2/3 its original size (1/3 eroded). Engine corrosion will increase if
eroded anodes are not replaced.
CAUTION
Do not paint or coat anodes or their mounting
surfaces.
External Anodes
Anodes mounted externally on the engine should be inspected
every 3 months, or more frequently if the engine is operated in salt
or polluted water.
Inspect sacrificial trim tab
(1)
for erosion.
Inspect stern bracket anode
(2)
for erosion.
Crankcase Anode
The powerhead is protected by an anode mounted in the
crankcase under the cylinder head. Replace crankcase
anode
(3)
when service work requires removal of the cylinder head
or when a complete overhaul of the engine is performed.
Installation Test
Use the following procedure to test for proper installation of
anodes. Make sure anode surface is clean before testing.
1. Calibrate an ohmmeter on high ohms scale.
2. Connect one meter lead to a ground on the powerhead
and the other lead to the anode. The ohmmetershould show
a low reading. If not, remove the anode and clean the surface
where it was mounted. The anode and its mounting hardware
should also be cleaned. Install anode and retest.
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