The use of coolant in diesel generator solves the problems of poor cooling and high temperature of the diesel generating set. Usually, we should replace the cooling liquid every one and a half years to two years. The standard replacement cycle of the cooling liquid will be very helpful for the genset protection. It can form a protective film on the surface of cylinder sleeve of the generator set so as to prevent the occurrence of cavitation and reducing wear and corrosion, which can prolong the maintenance intervals of the genset and reduce the maintenance cost. On the contrary, non-replacement for a long time, it will definitely reduce the using effects. So what problems should be paid attention to in the process of using diesel generator coolant?
Diesel Generators can have issues with the cooling systems.
Here we offer advice for on site checking of what to check before calling an engineer.
Operator’s Maintenance
The most important link in the maintenance chain is the engine operator. His daily and weekly checks of the cooling system and reports on any questionable conditions he observes will help prevent engine breakdown on the job and provide valuable information to engine repair people.
Each must be recorded and reported as and when they are found.
Diesel Generator Checks Before Start-up
1. Water level.
2. Cleanliness of coolant.
3. Radiator cap gasket.
4. Hose and connections for leaks or hose collapse.
5. Engine lubricating oil level.
Note
Oil level too low or too high will cause overheating and possible loss of the coolant.
6. Check for water in the oil and vice versa.
7. Inspect the fan for bent or damaged blades.
8. Check the belt for tension and condition.
9. Inspect the radiator for bent core fins or accumulation of debris. Check shutters for
damage or linkage wear.
10. Check for leaks at the cooler, water pump, or other accessories.
Diesel Generator Complaints and Causes
Loss of coolant due to external leakage.
1. Leaking pipe plugs, such as core plugs, which seal off coolant passages.
2. Loose clamps, faulty hose and piping.
3. Leaking radiator: Core hole plugs are sometimes loosened by corrosion or vibration.
These same conditions, or frozen coolant, can cause core seals to open up.
4. Leaking radiator, de-aeration top tank or surge tank.
5. Leaking gaskets due to improper tightening of cap screws, uneven gasket surfaces or
faulty gasket installation.
6. Leaking drain cocks.
7. Leaking water pump: Badly worn or deteriorated seals are the cause of leaks at the
pump. Premature failure of the pump seals often results from suspended abrasive
materials in the cooling system, or excessive heat from lack of coolant or cavitation.
8. Leaks at engine cylinder head gasket.
9. Leaks at upper cylinder liner counter bore.
10. Leaking engine or auxiliary oil cooler.
11. Leaking air intake after cooler (intake air heater in some cases).
12. Leaking water manifold and/or connections.
Loss of Coolant Due to Internal Leakage
1. Leaking engine cylinder head gasket: Coolant passes into the cylinders or the crankcase.
2. Cracked engine cylinder head: Coolant passes into cylinders and is blown out of the
exhaust.
3. Deteriorated, severed or chafed liner packing; defective liner packing bore: Coolant
passes into the engine crankcase.
4. Improperly seated or defective sleeves: Coolant can pass into the cylinder, crankcase,
and, if the heads have cylindrical injectors, coolant can enter the fuel system if it gets
past the injector body O-ring.
5. Porous cylinder block or head casting: Coolant can pass into the crank case via holes in
the system jacket. If the cylinder heads have internal fuel passages, coolant can
enter the fuel system via holes in the wall of the fuel rifle which adjoins coolant passages.
6. Cracked or porous water cooled exhaust manifold and faulty manifold to head mounting
gaskets. Coolant passes into the cylinder or out through the exhaust system.
7. Leaking engine or accessory oil cooler: Coolant passes into the oil side of the cooler
when the engine is shut down. The reverse almost always occurs when the engine is
operating.
8. Leaking engine air intake after cooler or intake air heater: Coolant passes into the
cylinders on naturally aspirated engines, also on turbo charged engines when the intake
manifold pressure is less than the coolant pressure.
Loss of Coolant Due to Overflow
1. Over filled radiator: As the engine reaches normal operating temperatures, the coolant
expands, and due to a lack of expansion space, unseats the pressure cap or relief valve,
allowing the coolant to pass out through the overflow pipe. This does not occur with a
properly designed top tank – expansion space compensates for this.
2. Slush freeze or frozen coolant resulting from insufficient antifreeze in the system or
poor mixing of antifreeze and water.
3. Dirt, scale or sludge in the cooling system.
4. Plugged radiator core.
5. Restriction or plugging of fill line due to routing and/or deterioration.
6. Combustion gas entering the cooling system and displacing the coolant causing it to
overflow.
7. More water introduced in the area above the baffle than the fill line can handle.
8. Improperly routed or sized fill line.
9. Excessive air intake temperatures.
Diesel Generator Engines Overheating
1. Poor circulation of coolant caused by collapsing of soft hose and restriction.
2. Over fuelling the engine.
3. Radiator shutter malfunction or improper adjustment of the thermal controls.
4. Incorrect adjustment or malfunction of variable pitch or modulating fans.
5. Crankcase oil level too high: Crankshaft dips in oil and causes a corresponding increase
in temperatures due to friction and parasitic load on the engine. Crankshaft oil dipping can
also be encountered when operating an engine beyond the angles for which the oil pan was
originally designed.
6. Dirty engine exterior: Heavy accumulations of dirt and grease can severely hinder normal
heat dissipation through the exterior walls of all the engine components.
7. Pressure of air in the cooling system: The following are the most common causes of air
entrapment:-
A. Low coolant level due to leaking water pump or leaks at hose and/or coolant
accessories.
B. Leaking air intake aftercooler.
C. Leaking engine or air compressor cylinder head gasket.
D. Improperly seated injector sleeve.
8. Inadequate cooling capacity: This condition can be the result of misapplication of one or
any combination of the following cooling system components:-
A. Radiator
B. Top Tank
C. Surge Tank
D. Fan
E. Fan Shroud
F. Water Pump
G. Auxiliary Coolers
H. Re-circulation Baffles
I. Fan Speed
9. After boil: Coolant boils and overflows after the engine is abruptly shutdown following
heavy loading.
10. Improper fan belt tension.
Coolant Contaminated with Combustion Gases
1. Cracked cylinder head.
2. Blown head gasket.
3. Injector sleeves leaking.
Coolant Contaminated with Fuel Oil
1. Injector sleeves leaking.
2. Porous cylinder head casting: The fuel enters the cooling system through holes in the wall
of the fuel rifle which adjoins the coolant passages.
Diesel Generator -WATER PUMP
Coolant Circulates at High Pump Speed Only
1. Badly deteriorated water pump impeller: Impeller damage is primarily caused by
corrosion and cavitation erosion.
2. Excessive impeller to body clearance.
3. Loose water pump drive belts.
4. Impeller slipping on the shaft.
5. Cracked impellers.
Fan or Water Pump Belts Break Prematurely
1. Foreign material falls in drive.
2. Shock or extreme overloads.
3. Belt damaged on installation by localised stretching.
4. Belts not properly matched.
5. Pulley mis-aligned.
6. Pulley nicked or rough.
7. Guard or shield interfering during operation.
Engine Operates Too Hot or Overheats When Loaded and Coolant is Known to be at the Proper Level
1. An altered horsepower rating of an engine or new engine installation which exceeds the
original design of the cooling system.
2. Clogged radiator air passages.
3. Damaged radiator core fins.
4. Heat exchanger element which contains heavy lime and scale deposits.
5. Thermostat not opening fully.
6. Fan shrouding missing, damaged, or improperly positioned with respect to the fan.
7. Re-circulation baffles on the sides of the radiator missing or damaged.
8. Fan drive belts slip: Impeller slips on the water pump shaft.
9. Clogged coolant passages, radiator, and engine.
10. Faulty automatic radiator shutters: Shutters only open partially or open too late.
11. Faulty thermatic or modulated fan drive: Fan engages too late or operates too slowly.
12. Faulty variable pitch fan: Fan operates with the blades at an insufficient pitch.
Diesel Generator Engine Coolant Temperature Too Low
1. Thermostat stuck in open position, or malfunctions, to allow premature opening.
2. Thermostat seal lip deteriorates and hardens allowing the coolant to bypass the closed
thermostat and enter the radiator.
3. Excessive bypassing of coolant to the radiator, with the thermostat closed and properly
sealed.
4. Engine is exposed to very low temperatures and high wind with a low load factor.
5. Water through the core due to a leaking de-aeration baffle.
Diesel Generator Lack of Temperature Control or indicators?
1. Defective Thermostat: Thermostat fails to open at the proper coolant temperature range
and/or does not open completely.
2. Defective Thermostat Seal: Coolant leaks by the seal and onto the water pump; therefore
bypassing the radiator.
3. Operating engine having a pressurised cooling system without a pressure cap, with a
defective pressure cap or a defective self-contained relief valve.
Clogged Water Filter Element
1. Contamination of the coolant caused by soluble oil, engine lube oil, engine fuel, or rust,
scale and lime.
2. Contamination of the cooling system with dirty fill or make-up coolant.
3. Use of anti-leak additive.
Corrosion, Rust and Scale Build-up Occurs in the Cooling System even after the Water Filter is Serviced Regularly
1. Insufficient water filter capacity.
2. Improper water filter installation.
3. Careless servicing of the water filter.
4. Aeration of the coolant: Free oxygen and carbon dioxide contained in the air are highly
corrosive.
Coolant selection: Select clean fresh water such as rainwater, tap water and river water. The well water and underground water (Hard water) shouldn’t be used directly, because they contain more minerals, which is easy to form limescale in the water tank of diesel engine, influence the cooling effect and even result in malfunction. If there is only hard water, it must be light softened before using. The softening method usually refers to the boiling method. Boil the water, add 0.67g caustic soda to per liter of water, and use the upper water after precipitation.
Cool the diesel engine with seawater is not allow
When the diesel engine is used below 0°C, it should prevent the coolant freezing since it may cause the cracking of relevant parts. Therefore, when the diesel engine finishes running, the cooling liquid of each parts should be discharged.For adopting the models of closed cycle cooling system, it can be equipped with appropriate antifreeze coolant according to the local minimum ambient temperature.
The formula of commonly used antifreeze coolant is as follows:
When equipped with the flammable antifreeze coolant, you should pay attention to fire safety since both ethylene glycol and alcohol are inflammable materials. Before using antifreeze coolant, the dirt in the cooling system should be cleaned to prevent the production of new chemical precipitates, which will affect the cooling effect. For the diesel generator that used the antifreeze coolant, it is not necessary to let out the coolant every time after stopping, but it should be regularly added and check the composition.
Do not use 100% antifreeze as coolant
If there is much limescale and dirt in the cooling system of diesel engine, clean it with cleaning solution. The cleaning solution can be made from water, soda water(Na2CO3) and water glass (Na2SiO3). Namely, add 40g soda water and 10g water glass to each liter of water. When cleaning, pour the cleaning solution into the cooling water chamber of the diesel engine. Drive the diesel engine to operate, when the outlet water temperature is greater than 60°C, continue to run forabout two hours and then parking, and release the cleaning solution. After the diesel engine is cooled, wash it with clean fresh water for two times, drain and pour into the cooling water and drive the machine to operate again. When the outlet water temperature reached 75°C, parking and release the sewage, after that, inject new cooling water.
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