Hobart Brothers 6910, Operation And Maintenance Manual With Illustrated Parts List

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(4) When the system is completely drained, close all drain valves except when draining for storage.
F. Cleaning the Cooling System
Drain and thoroughly flush the cooling system twice a year or more often if necessary. The appear-
ance of rust in the radiator, or in the coolant is an indication that the inhibitor has become weakened
and it is possible that some sludge has accumulated in the system. When this condition exists, pro-
ceed as follows:
(1) Run the engine until it reaches normal operating temperature; then stop the engine and drain the
cooling system
(Ref. Para. 6, E).
(2) Fill the cooling system with clean coolant
(Ref. Para. 6, H).
(3) Add a flushing compound, that is compatible with aluminum, to the cooling system in accordance
with the instructions furnished with the compound.
(4) Start the engine and flush the system as directed by the instructions furnished with the compound.
(5) After the system has been flushed and thoroughly cleaned of the compound, refill the clean cool-
ant
(Ref. Para. 6, H).
G. Cleaning the Radiator Core
Blow out insects and dirt from the radiator core air passages, using air or water under pressure. En-
gine overheating is often caused by bent or clogged radiator fins. When straightening bent fins, be
careful not to injure the tubes or to break the bond between the fins and tubes.
H. Filling the Cooling System
Add a cooling system corrosion inhibitor (for warm weather operation) or permanent antifreeze (when
the air temperatures expected are at fr32 deg F or lower). Antifreeze may be premixed if de-
sired. See Fig. 1 for cooling system capacity.
(1) Engine must be STOPPED. Close all drain valves except top water outlet valve. Leave this valve
OPEN to allow air to escape.
(2) Pour coolant into radiator slowly until system is filled to level of top drain valve. Close valve and
continue to fill system until coolant reaches a level approximately 1 inch below the radiator filler neck.
NOTE: If antifreeze solution is not premixed, pour required antifreeze in first. Install corrosion inhibitor
according to directions on container.
(3) Start the engine and allow it to idle. Add coolant if trapped air escapes from the system and the
coolant level falls.
(4) Continue to check coolant level until the engine reaches operating temperature. Add coolant, if
needed, to fill to the required level, 1 inch below filler neck. Install radiator cap.
NOTE: It is good practice to attach a card, indicating the cooling system contents, and the date serviced
to the radiator filler neck.
7. Generator Maintenance
The 400-Hz generator requires no maintenance or service other than periodic cleaning. The unit is
brushless, and bearings are permanently lubricated and sealed.
OM-2028
2-1 August 31/90 Revised
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