Onan MJA Series Service Manual page 28

26 COOLING SYS TE M
TROUBLE-SHOOTING CHART 2, COOLING SYSTEM
!
TROUBLE
POSSIBLE CAUSE
I
I
O\'ercool1ng
- !
I
Thermostat stuc k open.
I
Outlet temperature I
less than 140 0
i
I 1
I
I
Overheating NOTE:
I
1
Lack of cooling water*
, If the unit overheats,
I
the high water tem-I
I _I
perature switch Centrifugal water pump
stops
it
before not functioning*
damage would occur
Rubber impeller water
pump not functioning.
Water passages
restricted,
Thermostat stuck closed.
Water lines too small
or too long.
Improper lubrication.
Generator overloaded.
Rubber impeller
I
Impeller damaged.
pump failure
Impeller
drive
damaged.
I
Water lines restricted
or of improper size.
I
Premature rubber
I
Air leak in cooling sys ­
impeller failure
tem. (check for pock
, (under 500 hours
marks on impeller end
I
of operation)
surfaces).
Cavitation (vacuum
forming in water pump
when suction draw is
I
excessive) .
i
* -
Heat Exchanger Models Only.
REl'vIEDY
Replace thermostat,
Sect 3.1. 3.l.
Refill and check for
cause ?f loss.
\
impeller _
Check pump belt and
pump.
Repair or replace
Clean and flush cool-
ing system.
Replace thermostat.
Replace water lines.
Change to proper oil.
Reduce load.
I
Replace impeller.
I
Replace
drive
shaft.
Inspect oil spray hole
and drip hole in gear
cover.
Replace with larger
lines.
Replace impeller, re ­
pair air leaks. See
Sect 3. l.2 for air leak
test.
larger water inlet
Replace impeller, use
line.