The cooling system is of the combination closed-circuit type employing water as the coolant and relying for operation on forced circulation in the cylinder heads and on the convection of heat in the block. Jacket water is cooled in a special heat exchanger.
Fig. Cooling and warming-up system, 5П2, 8П2, 10П2, П12, П21, П22 and 5П4 diesel engines:1 – exhaust manifold; 2 — valve; 3 — heater; 4 — heater pump; 5 — thermometer; 6 — thermostat; 7 — radiator; 8 — pump; 9 — engine; 10 — cooling of engine; 11 — warming up engine
In the diesel engines of the stationary modification, the circulation of jacket wafer goes on in the following way.
Pump в delivers water through a lube of manifold 1 into the lower jacket of the cylinder head for cooling the hottest parts such as the exhaust passages, combusting chambers and injectors. Hot water leaves the upper jacket and flows into radiator 7 through thermostat 6. In the radiator, water is cooled down by a flow of air induced by a fait before returning into flic pump. When the jacket water temperature is below 70° C, the thermostat automatically directs the outflow from the jacket back into the pump, bypassing the radiator.
The cylinder block is cooled by the outflow from the cylinder head which cools down the cylinder heads in a uniform way due to the convection of heat. The starting of the engine at subzero temperature can be facilitated by incorporating healer 3 into the cooling system. To make the engine limber for starting, water is fed by pump 4 into the boiler of heater 3 wherefrom it reaches the jackets of the cylinder block and cylinder heads. On warming up the liners and cylinder heads, water is returned to pump 4 through thermostat 6.
Fig. Cooling system, 5Д2, ДС12, 5Д4 and 6ч diesel engines: 1 — expansion tank; 2 — thermometer; 3 — exhaust manifold; 4 — bleed cock; 5 — diesel engine; 6 — jacket water; 7 — jacket water pump; 8 — thermostat; 9 — jacket water cooler; 10 — outside water pump; 11 — outsido water; 12 – filter; 13 — oil cooler (on 6 ч engine)
In the diesel engines of the shipboard modification, pump 7 delivers water into the lower jacket of the cylinder head over a lube of manifold 3. Hot water leaves the upper jacket and flows into the expansion tank through the jacket of manifold 3 and then reaches cooler 9 through a tube, being then cooled in the cooler by outside water circulated with the aid of pump 10. The outflow from the cooler is returned to pump 7. When the jacket water temperature is below 70° C, thermostat 8 (this applies to the 5Д4 and 6ч engines) automatically directs the outflow from the manifold jacket into pump, bypassing cooler 9. The cylinder liners are cooled down due to the convection of heat when water enters the block jacket from the cylinder head jacket. Never cool the engine by outside water circulated directly through its jackets.
Bleed cock 4 in the exhaust manifold jacket serves to bleed trapped air from the system and there are drain cocks in the cylinder block jacket and the cooler as well as drain plugs in the pumps which all serve the purpose of draining the cooling system of water. The expansion tank enables protracted operation on the engine without topping up the system with water and provides a space for the water to expand therein on heating.
The temperature of the water outflow from the engine is monitored with the aid of a thermometer.
When the engine is bound to operate at subzero ambient temperatures, it is good practice to fill the cooling system with an antifreeze which is a liquid with a low freezing point.
Fig. Water pump, 5Д2 and 5Д2-1 diesel engines: 1 — casing; 2 — rotor; 3 — extension casing; 4, 14 — cover; 5 — grease cup; 6 — snap ring; 7, 9 — bushing; 8 — eccentric sleeve; 10 — stuffing box packing; 11 — gland; 12 — gland sleeve; 13 — ball bearing; 15 — vane; 16 — spring
Fig. Jacket and outside water pump, ДС8, and ДС12 diesei engines: 1 — gear; 2 — ball bearing; 3 — distance sleeve; 4 — casing; 5 — cup; 6 — grease nipple: 7 — cover plate; 8 — pump chamber body; 9 — spacer; 10 — screw; 11 — shaft; 12 — vane; 13 — spring
The water pumps found on the 5Д2, 5Д2-1, ДС8 and ДС12 engines are of the rotary type and they are attached to the timing gear cover plate. The journals of each rotor 2 are sealed by packing 10 of the stuffing boxes. A leak is eliminated by tightening gland 11. If this does not stop the leak, renew packing 10 of the stuffing box. To that end, taka down the defective pump from the engine and then proceed as follows. Remove extension casing 3, withdraw rotor 2 from sleeve 8 and remove defective packing 10. Repack both stuffing boxes, reassemble the pump and return it into its place. For a partial repacking of a stuffing box, the pump needs not be taken apart. Just loosen the glands and proceed with the job.
Fig. Water pump, 5П2, 8П2, 10П2 and 5П4 diesel engines: 1 – casing; 2 — impeller; 3 — shaft; 4 — spring; 5 — gland housing; 6 — pulley; 7 — hub; 8 — extremity piece; 9, 10, 26 — bolt; 11 — stopper ring; 12 — ball bearing; 13 — distance sleeve; 14 — grease cup; 15 — cup shell; 16 — cup; 17 — bellows; 18 — thermostat body; 19 – thermostat valve; 20 — thermostat cover with union; 21 — by-pass valve; 22 — thermostat union; 23, 24 — union; 25 — bracket; A — outflow to upper radiator tank; В — inflow from cylinder head; С — outflow to cylinder head; E — inflow from lower radiator tank
The water pump of the 5П2, 8П2, 10112, П12, П21, П22 and 5П4 diesel engines is a centrifugal one, is fitted to bracket 25 on the cylinder head and is driven from the crankshaft through a V-belt. Pump shaft 3 is sealed with a self-setting gland comprising housing 5, cup 16 with shell 15 and spring 4. The cup is tightly fitting the shaft and pressed to the gland housing by the spring. The gland housing is lapped lo a circular projection on pump casing 1. A defective gland will be betrayed by a heavy leak from a bleed hole in pump easing 1. The remedy is to dislodge the pump from bracket 25, to remove impeller 2 and renew the defective components of the gland.
Fig. Jacket water pump, 5Д4 and 6ч diesel engines: 1 — impeller; 2 — casing; 3— spring; 4 — gland housing; 5 — sleeve; 6 — gland; 7, 11 — ball bearing; 8 — shaft; 9 — gear; 10, 10 — key; 12 — distance sleeve; 13 — cup shell; 14 — cup; 15 — flange; 17 — cover; 18, 19 — shims; 20 — drain plug
The circulating pump the 5Д4, 8Д6 and 6ч engines are fitted with belongs to the turbine type and is attached to the timing gear cover plate. The pump is provided with a gear drive and self-setting seals on the pump shaft. When impeller 1 is set rotating, the water contained between the blades is induced by the centrifugal forces to move towards the outer periphery and into the discharge passage. Clearance A is adjusted by means of shims 18 and clearance B, by shims 19. For replacing worn components of the self-setting seal, cover 17 followed by impeller 1 must be removed.
Fig. Outside water pump, 5Д4 and 6ч diesel engines: 1 — casing; 2 — gland cup; 3 — gland housing; 4 — sleeve; 5 — set screw; 6 — distance sleeve; 7 — gear; 6, 15 — key; 9 — hall bearing: 10 — shait; 11 — gland; 12 – cup sheit; 13, 16 — shims; 14 — impeller; 17 — spring: 18 — cover; 19 — spiral passage; 20 – drain cock
The outside water pump of the 5Д4, 8Д6 and 6ч diesel engines is of the centrifugal self-priming type with a self-setting gland of the shaft; the pump is attached to the timing gear cover plate and is actuated by gears. The suction and delivery ports are found in the pump cover plate.
Spiral passage 19 provided in the pump cover plate within the limits of the pumping chamber is of a depth gradually decreasing from the centre, where the depth is a constant one, to the suction and delivery ports. These ports are located above the impeller axis and at a radius which is smaller than the radius of that portion where passage 19 is running so that some water is always left in the pump chamber after the pump has been stopped. If the water has drained from the pump, the latter must be primed preparatory to starting. When the impeller is set rotating, the water Filling the interior of the pump is impelled by the centrifugal forces to move toward the periphery where it fills spiral passage 19. Since the depth of this passage is a variable one, the volume of water contained between the blades varies at regular intervals, increasing at the suction port and decreasing at the delivery port. The water piston so formed, draws in and expels air during each such revolution of the impeller. On evacuating the suction pump of air, the pump starts sucking and delivering water. The self-priming properties of the pump depend on clearances A and В which must not exceed the values specified in the drawing.
Fig. Water cooler: 1 — shell; 2 — cock; 3, 20 — packing ring; 4 — plug; 5, 16 — cover plate; 6 — heat exchanging unit; 7 — pipe; 8 — hose; 9 — thermostat valve; 10 — thermostat body; 11 — thermostat cover; 12 — jacket water inlet; 13 — bypass valve of thermostat; 14 — thermostat; 15 — jacket water outlet; 17 — outside water inlet; 18 — outside water outlet; 15 — gasket
The water cooler of the trumpet type serves the purpose of cooling the circulating jacket water with outside water. This water is passed through the tubes of heat exchanging unit 6 while jacket water is passed through shell 1, washing the tubes from the outside. Baffle plates provided inside the shell lengthen the path travelled by jacket water.
The thermostat of the bypassing type automatically maintains the jacket water temperature at the requisite level. When the jacket water temperature is below 70° C, thermostat valve 19 is closed so that water flows into the water pump through bypass valve 21, bypassing the radiator (or the cooler). When the water temperature increases to between 80 and 86° C, the pressure inside bellows 17 builds up, causing the bellows to expand so as to uncover thermostat valve 19 and close bypass valve 21. This directs the flow of water into the radiator (or the cooler). The thermostat valve is provided with a small hole for bleeding the air trapped in the system and preventing air locks when the system is being filled with water.
Fig. Heater: 1 — outlet pipe; 2 — baffle plate and spark arrester; 3 — boiler; 4 — burner; 5 — heater plug; 6 — fan casing; 7 — reducer; 8 — fuel pump; 9 — eccentric pin; 10 — water pump; 11 — hard crank; 12 — water pump cover with inlet union; 13 — fan; 14 — fuel line; 15 — inlet union; 15 — cock; 17 — clamp; 18 — exhaust port
The heater serves the purpose of making the engine limber for starling at subzero ambient temperatures. Boiler 3 is connected to the delivery side of pump 10 by a hose and union 15. The turning of hand crank 11 causes pump 8 to feed fuel oil to burner 4 through line 14; the burner atomizes fuel which is then ignited with the aid of a heater plug. Hot gases are induced by fan 13 to flow along the boiler towards port 18. At the same time, pump 10 delivers coolant from the engine into the boiler.
The procedure of setting the heater into operation is as follows:
- Make sure hand crank 11 rotates freely, open the fuel shut-off cock and turn on the heater plugs.
- As soon as the coil of the pilot unit becomes cherry red, start cranking the hand crank without turning off the heater plugs. Turn off the heater plugs only when the sound of the flame is heard from the heater and proceed with the cranking at a rate of between 40 and 60 rpm until the coolant temperature is between 60 and 70° C. Remove the hand crank when the engine is under own power.
Important! The heater must be used only if the cooling system is filled with antifreeze; if water is used in the system, the freezing of the boiler and pump are likely to occur even if the engine is in operation.