Onan MDJE Service Manual

UNIT
MDJA
MDJB
MDJC
MDJE
MDJF
CLEANING AND FLUSHING THE
COOLING SYSTEM
To clean rust and scale deposits from captive water
systems, drain the system (as previously described),
and then fill with clean water and cleaner solution.
Use an approved chemical cleaner (such as the type
used for cleaning automotive cooling systems), and
follow the instructions provided by the supplier.
Chemical cleaners cannot be used with direct sea water cooled
marine engines.
WARNING Cleaning solutions fypicallyconfain
i strong chemicals that may cause
injury
if used improperly. Read all warning labels
before using.
When cleaning is complete, drain the cleaning solu-
tion and flush the system. For best results the engine
and heat exchanger should be reverse-flushed. Allow
the engine to cool as much as possible before flush-
ing with cold water.
Never pour cold wafer info a hot
D engine. Doing so may crack fhe
head or fhe cylinder block.
Do not operate engine
without coolant for even a few minutes.
CAPACITY IN QUARTS
ENGINE
AND HEAT EXCH.
4.5 (4.3 L)
9.5 (9 L)
4.5 (4.3 L)
9.5 (9 L)
2.3 (2 L)
Flush system if engine operation indicates clogged
passages or overheating.
To flush the engine:
1. Drain heat exchanger, cylinder block and exhaust
2,
3.
4.
5.
6.
To
1.
2.
3.
manifold. Removethermostats.
Remove the inlet and outlet hoses between the
engine and heat exchanger.
Close all drain plugs and attach the flushing gun
nozzle to the water outlet, as near the exhaust
manifold as practical. Restrict the normal inlet
line opening until the system fills with water, then
apply air pressure gradually. Repeat the process
until the flow of water from the cylinder block is
clean.
Remove flushing gun.
Reinstall thermostats, hoses, and drain plugs and
refill the system with the proper coolant.
When flushing is completed, check the system
thoroughly for any leaks uncovered by the clean-
ing operations.
flush heat exchanger:
Flush the engine water jacket as previously dis-
cussed.
First remove water outlet hose between engine
water jacket to the heat exchanger.
Flush both fresh water side and raw water side of
heat exchanger.
4.
5.
6.
Remove rubber impeller pump covertoflush raw
water side.
Flush
the water-cooled exhaust manifold.
When flushing is. completed, check the system
thoroughly for leaks.
FILLING COOLING SYSTEM
All closed or captive water cooling systems should be
filled with
50/50 mixture of antifreeze and clean
water. This is the amount recommended for satisfac-
tory corrosion protection and boil-over protection.
In extremely low temperatures
(-25OF or lower), it
may be necessary to increase the percentage of
antifreeze to provide adequate protection against
freezing. Follow the recommendation of the supplier
to determine the amount of antifreeze needed for the
lowesttemperature expected. The antifreeze solution
must be able to protect the cooling system during the
coldest winter weather. Table
1 shows the capacities
of the various cooling systems.
TABLE 1.
COOLING SYSTEM CAPACTIES
Heat Exchanger Filling
Improper filling of the heat exchanger (Figure 7) can
cause overheating of the engine-To prevent this pos-
sibility, follow these instructions whenever adding
coolant to the heat exchanger:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Remove fill cap.
Open fill vent valve (turn counterclockwise).
Remove vent plug (older city water cooled units
only).
Fill with coolant until vents begin to overflow.
Close fill vent valve (turn clockwise).
Replace vent plug (older city water cooled units
only).
Replace fill cap (prime pump on marine units).
Operate unit
10 minutes at full load; watch for
leaks.
Shut down unit.
17
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Onan MDJE Specifications

General

Brand	Onan
Model	MDJE
Category	Engine
Language	English