Steam Escape and Recirculation Tubes

b. Steam Escape and Recirculation Tubes. Some

a. General The usual radiator assembly consists of

overhead valve engines have a coolant tube connecting

a radiator core with a top tank and a bottom tank In some

the rear end of the cylinder head with top tank of the

designs, the tanks may be located on the sides of the

radiator, which allows escape of steam from the water

cores. The top, or inlet tank contains an outside pipe

jacket without causing overflow loss.

Coolant flows

called the radiator inlet and usually has a coolant baffle

through this tube into the radiator even with thermostat

inside and above, or at the inlet opening The radiator filler

valve closed, to prevent overcooling of the engine during

neck is generally attached to the upper part of the top tank

cold weather, the tube is equipped with a shut-off valve

and has an outlet to the overflow pipe The bottom tank

that can be closed. In another design, the tube from the

also has opening which is called the radiator outlet Refer

rear of the cylinder head is connected into the thermostat

to Chapter 3 for repair of radiator.

by-pass of that coolant flowing in the tube is recirculated in

the water jacket without entering radiator.

c. Core Hole Plugs In practically all engine water

jackets will be found a number of round openings which

are sealed by metal plugs driven into the holes. These

openings in the outside walls of the cylinder block or

cylinder head are necessary in the casting process, but

perform no cooling system function. The core hole plugs

which close these openings often incorrectly called "freeze

plugs" or "frost plugs". Although core hole plugs may be

forced out by a solid freeze-up In the water jacket, they are

not a safety device which can be depended on for the

prevention of freeze-cracking damage in the engine.

d. Other Fittings. In some engines a cover plate or

side plate is used to close a large opening on the side of

the cylinder block water jacket. One type of cover plate is

constructed with passages and outlet holes to provide for

distribution of coolant in a manner similar to that of the

water distribution tube. A few cooling systems have more

than one water outlet from the cylinder head and use an

assembly of metal piping called a "water manifold" to carry

the coolant to the radiator.

Figure 1-4. Radiator

1-8.

Fan and Shroud

b. Function of Tanks.

The top tank collects

(Fig 1-2).

incoming coolant and distributes it across the top of the

radiator core The baffle in the top tank assists in

a. Fan. Operation of the fan pulls a large volume of

distributing coolant to water tubes and also prevents

air through the radiator core Besides removing heat from

coolant from being thrown out of the radiator. The

the radiator, this flow of air also provides some direct air

overflow pipe provides an opening from the radiator for

cooling of the engine The fan provides most of the air flow

escape of coolant or steam that otherwise might cause

through the radiator at low road speeds when the forward

excessive pressure in the cooling system. The bottom

motion of the vehicle forces comparatively little air through

tank collects coolant flowing from the core and discharges

the core Reducing the size of the drive pulley increases

it through the radiator outlet.

the speed of the fan For operation in extremely hot

climates, larger fans and smaller pulleys are sometimes

c. Core Construction Practically all military cooling

installed.

systems have tubular radiator cores which consist of a

large number of vertical water tubes and many horizontal

b. Shroud. Military vehicles are generally equipped

air fins around the tubes. Water passages in the tubes are

with a tunnel-like structure around and behind the fan

usually very narrow, and the tube itself is made of very thin

called a shroud The purpose of the shroud is to direct the

metal

flow of air for most effective cooling. Some vehicles have

air baffles on the front side of the radiator to direct air flow

through the core.

1-9.

Radiator

(Fig 1-4).

1-4