Direct flushing

(3)

Engine block flushing.

flushing water pressure and air pressure (flushing gun) (7,

fig 2-1). Flushing may be accomplished by the following

ways.

CAUTION

(1) Direct flushing. Direct flushing is forcing water

through the radiator core from top to bottom, as it flows in

Do not use excessive pressure when flushing

normal service.

heater. Water shutoff valve on flush gun should

(2) Back flushing. Back-flushing is recommended

be only partially open.

periodically and in particular when anti-freeze solution is

(a) Allow radiator hoses to remain disconnected.

changed. A back-flushing gun should be used for best

Disconnect heater hoses from the engine connection and

results. The back-flushing gun employees both water and

not at the heater ends.

air under pressure. The intermittent application of air

(b) Using an adapter bushing, connect the flush gun

pressure causes turbulence in the water which aids the

(4, fig 2-1) to one of the heater hoses. Flush heater using

flushing action.

continuous water flow and intermittent air blasts as before.

(3) Flushing engine block. Since the engine block

shares the same coolant, when the radiator is flushed, the

flush gun but leave heater hoses disconnected.

engine block should also be flushed. When a radiator is

(d) Remove engine thermostat. Attach flush gun

removed or when a new radiator is installed, engine block

discharge hose to thermostat opening with the use of the

flushing is mandatory. If engine block is not flushed, loose

proper hose adapter.

scale will collect at top of core and eventually plug radiator.

(e) Open engine block drain cocks or preferably

b. Flushing Procedures

remove them. Make sure that drain cock openings and

(1) Direct flushing.

engine heater connections will not cause water hazard to

(a) Screw radiator cap on filler neck and attach

engine parts or to personnel.

a lead-away hose to outlet connection of lower tank.

(f) Fill engine block with water from flush gun and

(b) With flushing gun in inlet connection of

operate with short air blasts until clear water is discharged.

upper tank, fill radiator with water.

(g) Replace all removed components and fill cooling

system to proper level with prescribed coolant. Run

break loose grease, sludge, rust, and scale within radiator,

engine a short time to remove trapped air and recheck

it may be necessary to add some good radiator cleaner.

coolant level.

(d) When deposits are loosened, turn water off

and admit compressed air to radiator in short blasts,

3-9.

Vat Cleaning

adding water between blasts until water drains out clear

and at a normal rate. The air must be applied gradually,

Flo-Tester. Before vat cleaning, all radiators

as the radiator will stand only a limited pressure.

should be Flo-Testes (para 3-18). The gallons per minute

(2) Radiator back-flushing

(GPM) flow should be recorded to be compared with the

GPM reading after cleaning.

CAUTION

Cleaning

Do not use constant air pressure because danger

(1) General. Before repairing, a radiator should be

of radiator rupture.

cleaned both inside and outside. Outside cleaning is for

ease of soldering during the repair. It is also important for

(a) Remove radiator cap, drain radiator and

removing any paint and oxide formations that might hide a

disconnect inlet and outlet hoses from radiator.

small leak. Inside cleaning Is required to restore cooling

(b) Attach a lead-off hose to upper radiator inlet

capacity, remove scale formations, dirt and oil that can

neck. This will divert the flushing water away from the

temporarily seal a small leak. A heated vat (6, fig 2-1) with

working area and eliminate any water hazard to personnel

cleaning solution is the most effective method of cleaning.

or vehicle.

The vat must be large enough to contain the entire

radiator. It should be constructed of material that is

radiator outlet neck.

unaffected by the caustic action of the cleaning compound.

(d) Connect flush gun to both air and water supply

The vat solution must be heated and some means of

source and operate water control on flush gun to fill

controlling and regulating the temperature should be used.

radiator.

Drains should be provided for changing the solution when

(e) When radiator Is filled, replace radiator cap while

it becomes dirty from continued use.

continuing water flow. Operate air control valve on flush

gun intermittently to produce short air blasts.

(2)

Hot cleaning vat solution.

(f) Continue flushing with constant water flow and

short blasts of air until clear water is discharged.

3-4