1992 Johnson Evinrude "EN" 9.9 thru 30 Service Manual, P/N 508142, Page 40Get this manual
AnodesTesting and Replacement Erosion or disintegration in salt or brackish water indicates the anodes are performing their functionThe anodes should be inspected at intervals and replaced when necessary, or corrosion of the engine will increaseIf any anode has been reduced to 03 its original size (13 eroded) it must be replaced!
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t=J ohmmeter on appropriate scaleConnect one meter lead to