Troubleshooting Cooling System on Generator
The most important link in the maintenance chain is the diesel 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.