TM 9-803 79-80
I/,-TON
4 x 4 TRUCK (WILLYS-OVERLAND and FORD MODEL GPW)
MODEL MB
Thermostat Opens Fully
Temperature 80.
145O to 155OF
__...._.._..........._.,.._. open
. ...... .... .
. .._.......
170°F
gage type
Capillary
MAINTENANCE.
a. The cooling system must be inspected in accordance with preventive maintenance procedures (pars. 13 and 16). When draining the cooling system refer to caution plate on the instrument panel (fig. 7). General maintenance of the cooling system consists of the following procedures. (1) which below
Keep sufficient coolant in the system. Use clean water to must be added the specified rust inhibitor; at temperatures 32OF, add proper quantity of antifreeze solution (par. 7).
(2) Drain, flush, and refill system whenever any accumulation of rust or scale. Clean system as before and after using antifreeze solution.
inspection seasonally
reveals as well
(3) If engine overheats due to lack of coolant in the system, do not add cold water immediately. Let engine cool so that radiator does not boil, start engine, and add water slowly to prevent damage to cylinder block and head. (4) visible
Do not overfill radiator. Fill through the radiator filler hole.
radiator
to bottom
(5) Keep cylinder head, water pump, hose clamps, tions leakproof. Replace deteriorated or leaky hose. (6) (7) system b.
Adjust
fan belt and replace
and Refilling
and connec-
as required.
Test periodically for air suction (subpars. c and d below). Draining
of baffle
and exhaust
gas leaking
into
System.
(1) Drain the cooling system, when required, by opening the drain cocks at the lower left corner of the radiator, and at the right front corner of the cylinder block. Loosen the pressure-type radiator cap to break any vacuum which might prevent proper draining, If solution is to be saved, catch it in a clean container. If system is not to be refilled immediately, attach a tag to the steering wheel, warning personnel about the system being drained. (2) Refill the cooling system by first closing the two drain cocks tightly. Use clean water available, preferably soft water (water with low alkali content or other substances that promote rust and scale). Fill system through radiator filler pipe until level is up to lower edge of baffle visible through filler hole. Install radiator cap, and turn clockwise to tighten. Start engine and warm up. Check coolant level in radiator, and add more if required. c. Air Suction Test. The air suction test is used to determine if air is entering the coolant, possibly due to low coolant level in the radiator, leaky water pump, or loose hose connections. To make test, 138
