Anodes - Inspection And Testing; External Anodes; Powerhead Anode; Installation Test - TOHATSU NB-1000 Service Manual

SECTION 2
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 anodes 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.
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.
1
Inspect the sacrificial trim tab (1) for erosion.
2
Inspect the mid-section or lower unit anode (2) for erosion.

Powerhead Anode

The powerhead is protected by an anode mounted in the cylinder head
or cylinder. The anode should be replaced whenever 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 the anode.
Make sure the surface of the anode 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 ohmmeter should show a Iow reading.
If not, remove the anode and clean the surface where it was
mounted. The anode and its mounting hardware should also be
cleaned. lnstall anode and retest.
2-38
CAUTION
T1977
T1978
1-/ 2-Cylinder