Onan MJA Series Service Manual page 26

24 COOLING SYSTEM
3. 1. 4.1 Maintenance. - Maintain the closed water system the same as
an automotive radiator cooling system. Clean and flush it once a year
and use an anti-freeze
if
there is danger of freezing. Use a rust inhib ­
itor in the expansion tank (closed water system).
In the sea water system. check periodically for .air leaks, rubber im ­
peller wear or damage, and restricted lines.
The raw water side of the heat exchanger is protected from corrosion
by a zinc pencil mounted on a pipe plug in. one end of the heat exchanger.
Inspect the pencil at least every 2 months and replace
if
deteriorated to
less than 1/2 origtllal size, Fig
3. 1.
G.
I - -
/ 7 "
~
".
~1:1
SEA WATER OUT
2 CYLINDER MODELS
~
I "
Ii
r'
+1
.1
4 CYLINDER MODELS
ACTUAL SIZE-REPLACE
WHEN DETERIORATE 0 TO
ONE HALF OF ORIGINAL
SIZE.
FIG 3. 1. F - DRA1NING HEAT FIG 3.1.G - ZINC PENCILS
EXCHANGER
3.1.4.2 Cleaning. - Clean and flush the COOling system at least once a
year and more often
if
conditions warrant. To clean the closed water
system, drain and refill with radiator cleaner. When chemical clean..;
ing is completed, according to the cleaner manufacturer's instructions,
flush the cooling system to wash out deposits loosened by the chemical
cleaning.
Flush the engine water jacket as discussed in Sect 3.1.1.2 except that
the hose from engine water jacket to heat exchanger should be removed
for the water outlet. Flush both closed water side and raw water side
of the heat exchanger. Remove the rubber impeller pump cover to flush
the raw water side. Also flush the water cooled eXhaust manifold. When
flUShing is completed, check the system thoroughly for leaks uncovered
by the cleaning operations.
41
,.,
,./