MECHANICAL ENGINEERING DEPARTMENT
Guided By: - K C PATEL Presented By: -
PATEL VAIBHAV JAYANTIBHAI
CHAUDHARI JAINISH PRAVINKUMAR
this project is developed not only single evenhandedly but it is a team effort to sail our ship of project to the coast of success. So we would like to express our sincere thanks to all the dignitaries who were involved in making this project successful. I thank my friends for their support. Lastly it is our great pleasure to acknowledge our obligation to all those who were directly or indirectly involve in making my project a successful piece of work.
The project report title “HOW TO STOP OVERHEATING IN IC ENGINES“is self-explanatory. It is indeed to endow with a comprehensive study of the technical and theoretical aspects of those problems. The entire topic covered in the report is essential for complete understanding and survey.
Further, report contains explanation and detail of various type of problems faced in LIQUID COOLING SYSTEM IN INTERNAL COMBUSTION ENGINE and analysis of the problems, their causes and remedies.
Hence at the end of the report, I will be able to get satisfactory solutions for the problems faced.
We know that in case of Internal Combustion engines, combustion of air and fuel takes Place inside the engine cylinder and hot gases are generated. The temperature of gases Will around 2300-2500°C. This is a very high temperature and may result into burning Of oil film between the moving parts and may result into seizing or welding of the same. So, this temperature must be reduced to about 150-200°C at which the engine will work Efficiently too much cooling is also not desirable since it reduces the thermal Efficiency so, the object of cooling system is to keep the engine running at its most Efficient operating temperature It is to be noted that the engine is quite inefficient when it is cold and hence the cooling System is designed in such a way that it prevents cooling when the engine is warming up And till it attains to maximum efficient operating temperature, then it starts cooling. It is also to be noted that
(a) About 20-25% of total heat generated is used for producing brake power
(b) Cooling system is designed to remove 30-35% of total heat.
(c) Remaining heat is lost in friction and carried away by exhaust gases.
After studying this unit, you should be able to:
• understand the methods of cooling of IC engine,
• explain and know the water cooling system of IC engine.
WATER COOLING SYSTEM
In this method, cooling water jackets are provided around the cylinder, cylinder head, Valve seats etc. The water when circulated through the jackets, it absorbs heat of
Combustion this hot water will then be cooling in the radiator partially by a fan and
Partially by the flow developed by the forward motions of the vehicle the cooled water
Is again recalculated through the water jackets
1.2 NEED OF WATER COOLING SYSTEM
A system, which controls the engine temperature, is known as a cooling system.
The cooling system is provided in the IC engine for the following reasons:
• The temperature of the burning gases in the engine cylinder reaches up to 1500 to 2000°C, which is above the melting point of the material of the cylinder body and head of the engine. (Platinum, a
metal which has one of the highest melting points, melts at 1750 °C, iron at 1530°C and Aluminum at 657°C Therefore, if the heat is not dissipated, it would result in the failure of the Cylinder material
• Due to very high temperatures, the film of the lubricating oil will get oxidized, thus producing Carbon deposits on the surface. This will result in piston seizure.
• Due to overheating, large temperature differences may lead to a distortion of the engine Components due to the thermal stresses set up.
This makes it necessary for, the temperature Variation to be kept to be minimum
1.3 LIQUID COOLING SYSTEM IN INTERNAL COMBUSTION
Components of Water Cooling SystemWater cooling system mainly consists of
(b) Water Jackets,
(c) Thermostat valve,
(d) Water pump,
(e) Fan and,
(f) Antifreeze mixtures.
It mainly consists of an upper tank and lower tank and between them is a core. The
Upper tank is connected to the water outlets from the engines jackets by a hose
Pipe and the lover tank is connect to the jacket inlet through water pump by means
Of those pipes when the water is flowing down through the radiator core, it is cooled partially by the fan which blows air and partially by the air flow developed by the forward Motion of the vehicle as shown through water passages and air passages, wafer and air will be flowing for cooling purpose.
It is to be noted that radiators are generally made out of copper and brass and their Joints are made by soldering. It is a valve which prevents flow of water from the engine to radiator, so that
Engine readily reaches to its maximum efficient operating temperature. After
Attaining maximum efficient operating temperature, it automatically begins
Functioning generally, it prevents the water below 70°C.
Cooling water jackets are provided around the cylinder, cylinder head, and valve seats
And any hot parts which are to be cooled. Heat generated in the engine cylinder,
Jackets absorb this heat and gets hot. This hot water will then be cooled in the Radiator
It is a valve which prevents flow of water from the engine to radiator, so that
Engine readily reaches to its maximum efficient operating temperature. After
Attaining maximum efficient operating temperature, it automatically begins
Functioning generally, it prevents the water below 70°C.This type of thermostat valve which is generally used It contains a bronze bellow containing liquid alcohol. Bellow is connected to the butterfly valve disc through the link. When the temperature of water increases, the liquid alcohol evaporates and the bellow expands and in turn opens the butterfly valve, and allows hot water to the radiator, where it is cooled.
It is used to pump the circulating water. Impeller type pump will be mounted at the Front end. Pump consists of an impeller mounted on a shaft and enclosed in the pump casing. The pump casing has inlet and outlet openings. The pump is driven by means of engine output shaft only through belts. When it is driven water will be pumped.
FanIt is driven by the engine output shaft through same belt that drives the pump. It is provided behind the radiator and it blows air over the radiator for cooling purpose.
In western countries if the water used in the radiator freezes because of cold climates, then ice formed has more volume and produces cracks in the cylinder blocks, pipes, and radiator. So, to prevent freezing antifreeze mixtures or solutions are added in the cooling water.
The ideal antifreeze solutions should have the following properties:
(a) It should dissolve in water easily.
(b) It should not evaporate.
(c) It should not deposit any foreign matter in cooling system.
(d) It should not have any harmful effect on any part of cooling system.
(f) It should not corrode the system.
No single antifreeze satisfies all the requirements. Normally following are used as antifreeze solutions:
(a) Methyl, ethyl
and propyl alcohols.
(b) A solution of alcohol and water.
(c) Ethylene Glycerol.
(d) A solution of water and Ethylene Glycerol.
(e) Glycerin along with water, etc.
(a) Uniform cooling of cylinder, cylinder head and valves.
(b) Specific fuel consumption of engine improves by using water cooling system.
(a) It depends upon the supply of water.
(b) The water pump which circulates water absorbs considerable power.
(c) If the water cooling system fails then it will result in severe damage of Engine.
(d) The water cooling system is costlier as it has more number of parts. Also it requires more maintenance and care for its parts.
(e) Coolant freezing problem may occur in low atmospheric temperature if the
Antifreeze liquid doesn't mix with coolant.
2 POSSIBLE CAUSES OF OVERHEATING
Overheating can be caused by anything that decreases the cooling system's ability to absorb, transport and dissipate heat: A low coolant level, a coolant leak (through internal or external leaks), poor heat conductivity inside the engine because of accumulated deposits in the water jackets, a defective thermostat that doesn't open, poor airflow through the radiator, a slipping fan clutch, an inoperative electric cooling fan, a collapsed lower radiator hose, an eroded or loose water pump impeller, or even a defective radiator cap.
One of nature's basic laws says that heat always flows from an area of higher temperature to an area of lesser temperature, never the other way around. The only way to cool hot metal, therefore, is to keep it in constant contact with a cooler liquid. And the only way to do that is to keep the coolant in constant circulation. As soon as the circulation stops, either because of a problem with the water pump, thermostat or loss of coolant, engine temperatures begin to rise and the engine starts to overheat.
The coolant also has to get rid of the heat it soaks up inside the engine. If the radiator is clogged with bugs and debris, or if its internal passages are blocked with sediment, rust or gunk, the cooling efficiency will be reduced and the engine will run hot. The same thing will happen if the cooling fan is not engaging or spinning fast enough to pull air through the radiator.
The thermostat must be doing its job to keep the engine's average temperature within the normal range so the engine does not overheat. If the thermostat fails to open, it will effectively block the flow of coolant and the engine will overheat.
Exhaust restrictions can also cause the engine to overheat. The exhaust carries a lot of heat away from the engine, so if the catalytic converter is restricted, or a pipe has been crimped or crushed, exhaust flow can be restricted causing heat to build up inside the engine.
It's also possible that your engine really isn't overheating at all. Your temperature gauge or warning lamp might be coming on because of a faulty coolant sensor
Overheating may cause dangerous results such as burnout.
3 HOW TO SOLVE THE OVERHEATING PROBLEMS:
1.Bad Thermostat --
Severe engine overheating can often damages a good thermostat. If the engine has overheated because of another problem, therefore, the thermostat should be tested or replaced before the engine is returned to service.
One way to check the thermostat is to start the engine and feel the upper radiator hose (or use an infrared non contact thermometer to read its temperature). The hose should not feel uncomfortably hot until the engine has warmed-up and the thermostat opens. If the hose does not get hot, it means the thermostat is not opening.
2. Cooling system leaks --
Loss of coolant because of a coolant leak is probably the most common cause of engine overheating. Possible leak points include hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head(s) and block.
Make a careful visual inspection of your entire cooling system, and then PRESSURE TEST the cooling system and radiator cap. A pressure test will reveal internal leaks such as seepage past the head gasket as well as cracks in the head or block. A good system should hold 12 to 15 psi for 15 minutes or more with no loss in pressure. If it leaks pressure, there is an internal coolant leak (most likely a bad head gasket but possibly also a cracked cylinder or engine block).
It is important to pressure test the radiator cap, too, because a weak cap (or one with too low a pressure rating for the application) will lower the coolant's boiling point and can allow coolant to escape from the radiator.
3. Leaky Head Gasket --
Bad news because repairs are expensive. A leaky head gasket can allow coolant to seep into the engine's cylinders or crankcase. Symptoms include a loss of coolant with no visible external leaks, and white steam in the exhaust, especially after restarting the engine when it has sit for awhile. A leaky head gasket can be diagnosed by pressure testing the cooling system, or by using a "block checker" that pulls air from the cooling system into a cylinder that contains special blue colored leak detection liquid. If there are any combustion gases in the coolant, the color of the liquid inside the detector will change from blue to green. A leaky head gasket can often be temporarily sealed by adding a sealer product to the cooling system. But for bad leaks or ones that cannot be stopped with sealer, the head gasket has to be replaced.
4. Fan Not Working --
With mechanical fans, most engine overheating problems are caused by a faulty fan clutch, though a missing fan shroud can reduce the fan's cooling effectiveness by as much as 50% (depending on the fan's distance from the radiator) which may be enough to cause the engine to overheat in hot weather or when working hard.5. Leaky Water pump --
Any wobble in the pump shaft or seepage would call for replacement. In some instances, a pump can cause an engine to overheat if the impeller vanes are badly eroded due to corrosion or if the impeller has come loose from the shaft. The wrong pump may also cause an engine to overheat. Some engines with serpentine drive belts require a special water pump that turns in the opposite direction of those used on the same engine with ordinary V-belts.
It does not happen very often, but sometimes the water pump impeller can loosen up on the pump shaft and not turn, although the water pump pulley appears to be turning normally. If the impeller does not spin, there will be little or no circulation of coolant through the engine. The only way to know if this is the problem is to remove the water pump and check the impeller to see that is is tight on the shaft. Also, some plastic impellers can become severely eroded over time. The water pump housing and/or impeller may also experience capitations The loss of blade area or an increase in clearance between the housing and impeller will reduce the flow of coolant and can lead to engine overheating.
* Slipping Belt --
Check belt tension and condition. A loose belt that slips may prevent the water pump from circulating coolant fast enough and/or the fan from turning fast for proper cooling.
*Plugged or Dirty Radiator --
Dirt, dead bugs and debris can block air flow through the radiator and reduce its ability to dissipate heat. Internal corrosion and an accumulation of deposits can also block the flow of coolant. A good way to find internal clogs is to use an infrared thermometer to "scan" the surface of the radiator for cold spots. If clogged, the radiator should be removed for cleaning or replaced. Back flushing the cooling system and/or using chemical cleaners can remove rust and hard water scale, but may do little to open up a clogged radiator.
1. Check and repair the thermostat valve’s spring if possible replace it with new one.
2. Inspect the whole cooling system carefully there might be problems in pipes or joints leakage, replace the pipes or if the leakage is minor try to shut the pinholes
3. If the head gasket is bad or burst it should be replaced
4. Radiator fan doesn't work check the electrical connections wires and main supply (battery)
5. Tight the loose water pump belts and replace the brand new ones
6. If the radiator is jammed remove it from the system and clean the inner tubes with the fresh water with high pressure.
1. If your vehicle is outdated change the pulley systems with new versions (this upgrade could be expensive but the result will effective)
2.use high grade coolants than the required
3.clean the radiator protection grill twice in a week.
4. Avoid direct airflow on air filter in foggy or snowy seasons.
5. Keep your vehicle in cool place in summer time after using for long period
6. After shutting down the engine open the hood of the engine and let the atmospheric air pass through whole system
7. Make sure the parking brake is not applied during the running vehicle it may heat up the engine due to overload
After studying and observing and inspecting the cooling systems, we have the conclusion that overheating problem could not occur if the all above said parts and systems should repair or replaced on right time and right place
never avoid minor problems in system to avoid major possibilities.