Yanmar 4BY, Service Manual, Page: 170 / 275

COOLING SYSTEM
BY Service Manual 7-11
Repair
Figure 7-5
6. Engines having the optional high-rise exhaust
elbow: Open drain cock (Figure 7-5, (1)) and
allow water to drain. Remove and inspect zinc
anode
(Figure 7-5, (2)) .
IMPORTANT
NEVER use thread sealer or thread sealing
tape when installing zinc anodes. Anodes
must make good metal-to-metal contact to
perform properly.
7. Inspect condition of zinc anodes and replace as
necessary. See Check and Replace Zinc
Anodes on page 7-11 .
8. Close all drain cocks.
Check and Replace Zinc Anodes
There are zinc anodes in the seawater cooling
system and they should be inspected and replaced
periodically.
See Periodic Maintenance Schedule
on page 4-8 for the recommended frequency.
Figure 7-6
Zinc anodes are located in the heat exchanger
(Figure 7-6, (1)) and the charge air cooler
(Figure 7-6, (2)) .
A zinc anode is also located in the optional
high-rise elbow
(Figure 7-6, (3)) .
1. Remove each anode and inspect for corrosion.
Any anode having less than 1/2 its original size
remaining should be replaced.
IMPORTANT
NEVER use thread sealer or thread sealing
tape when installing zinc anodes. Anodes
must make good metal-to-metal contact to
perform properly.
2. Install each zinc anode using a new copper
gasket. Tighten to 25 N·m (18 ft-lb).
3. Start engine and check for water leaks.
000 3 66 3
(2)
(1)
000 3 659B
(1)
(2)
( 3 )