Service manual

CORROSION PROTECTION - ALL MODELS
SERVICE MANUAL NUMBER 28
90-863160 MAY 2000 Page 7A-21
High Reading
Cause Special Instructions
Stray current corrosion. If an electrical
current flowing along a metal conductor
leaves the metal for a water path, it will
cause ionization of the metal, and an area
of rapid corrosion.
Observe the reading while disconnecting
the electrical components one at a time
until you eliminate the high reading.
Correct the course of stray current.
Poor connection between MerCathode
reference electrode lead (brown) and “R”
terminal on controller.
Clean and /or tighten connection. Repair
wiring as required.
Faulty MerCathode reference electrode. Disconnect the reference electrode lead
(brown) from “R” terminal on the controller.
Connect the lead to the positive (+)
terminal of a digital multi-meter (set on
0-2000 millivolt scale). Connect the
negative (–) meter lead to the negative (–)
battery terminal. Note the meter reading;
then, repeat the test using MerCathode
Reference Electrode Tester 76675A1.
Both tools should produce the same
reading. If not, replace the reference
electrode.
Faulty MerCathode controller. Replace the controller.
Normal Reading But Corrosion is Evident
CORROSION ON THE ENTIRE STERNDRIVE UNIT
Cause
Special Instructions
The sterndrive unit is raised so that
the sacrificial anodic trim tab is out of
the water.
Leave the sterndrive unit in the IN/DOWN
position when the boat is moored to
ensure the trim tab is in the water,
providing protection.
CORROSION PROBLEM DEVELOPED AFTER REFINISHING THE DRIVE UNIT
Cause
Special Instructions
A steel wire brush was used to clean
the aluminum casting. Steel particles
became en-trapped and set up a
small galvanic cell.
Use only a nylon or bristle brush.
PAINT BLISTERING ON DRIVE UNIT
Cause
Special Instructions
Battery charger, using 110 volt
shore power improperly connected to
the battery.
Ensure the charger is connected
correctly.
INDEX