caterpillar 3208 DIESEL TRUCK ENGINE Reasons and treatment methods of cooling system temperature higher than normal heating
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The details are as follows：
1. Low Coolant Level... If the coolant level is too low.
not enough coolant wil go through the engine and radiator. This lack of coolant will not take enough heat from the engine and there will not be enough flow of coolant through the radiator to release the heat into the cooling air. Low coolant level is caused by leaks or wrong fling of the radiator. With the engine cool, be sure that coolant can be seen at the low end of the fill neck on the radiator top tank.
2. Bad Temperature Gauge...A temperature gauge which does not work correctly will not show the correct temperature. If the temperature gauge shows that the coolant temperature is too hot butother conditions are normal, either instal a gaugeyou know is good or check the cooling system with the 8T0470 Thermistor Thermometer Group.
3. Dirty Radiator... Check the radiator for detbris between the fins of the radiator core which prevents free air flow through the radiator core. Check the radiator for debris, dirt, or deposits on the inside ofthe radiator core which prevents free flow of coolant through the radiator.
4. Loose Belt(s)., Loose fan belts will cause a reduction in air flow. Tighten the belts according to V. Belt Tension Chart that is shown in Specification section of this Service Manual.
5. Bad Hose(s)... Bad hoses wth leaks can normaly be seon. Hoses that have no visual leaks can collapse"(pull together) during operation and cause a restriction in the flow of coolant. Hoses become soft and/or get cracks after a period of tirme. Hoses must be changed atter 50,000 miles or a year of use. The inside of a hose can deterioriate, and the loose particles of the hose can cause a restriction in the flow of coolant.
6. Shunt Line Restriction...A restriction of the shunt line from the radiator top tank to the engine water purmp inlet, or a shunt line not installed correctly. will cause a reduction in water punp efficiency. The result will be low coolant flow and overheating
7. Shutters Not Opening Correctly.. Check the opening temperature of the shutters. The shuttersmust be completely closed at a temperature below the fuly open temperature of the water temperature regulators.
8. Bad Waler Temperature Regulator(s)..A regulatorthat does not open, or only opens part of the way, can cause above normal heating. To test the thermostats, see the Testing and Adjusting section of this Service Manual.
9. Bad Water Pump...A water pump with a loose or damaged impeller does not pump enough coolant for correct engine cooling. Remove the water pump and check for damage to the impeller. If the impeller has no damage, check the impeller clearance. The clearance between the impeller and the housing is
0.28 to 0.84mm(011 to ,033 in).
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10. Air in Cooling System.. Air can get into the cooling system in different ways. The most common causes are not filing the cooling system correctly, and combustion gas leaking into thesystem. Combustion gas can get into the system through inside cracks or bad cylinder headqaskets. Air in the cooling system causes a reduction in coolant flow and bubbles in the coolant. Air bubbles hold coolant away from engine parts, preventing heat flow.
Air in the cooling system can be found by the BottleTest. The equipment needed to make this test is a one pint botle,a bucket of water and a hose which will fit the end of the overflow pipe of the radiator.
Before testing, make sure the cocling system is filedcorrectly. Use a wire to hold the relief valve in the radiatcr cap open. Install the radator cap and tighten it.
Put the hose over the end of the overflow pipe.
Start the engine and operate it at high idle rpm for a minimum of five minutes after the engine is at noxmal operating temperature, Use a cover on the radiator coreto keep the engine at operating temperature After five or more minutes at operating temperature, place the loose end of the hose in the bottie filled with water. Put the bottle in the bucket of water with the top down. It the water gets out of the bottle in less than forty seconds, there is too much exhaust gas leakage into the cooling system, Find the cause of the air or gas getting into the cooling system and correct as necessary.
11. Wrong Fan, Fan or Shroud Not in Correct Position...A wrong fan, or a fan or shroudin a wrong position will cause a reduction or a loss of air flow through the radiator. The fan must be large enough to send air through most of the area of the radiator core. Make sure the fan size, fan shroudand position of fan and shroud are according to the recommendations of the Truck Manufacturer.
12. Radiator Tco Small..A radiator which is toosmall does not have enough area to release the heat to the cooling air. This will cause the engine to run at higher than normal temperatures. Make sure the radiator size is according to therecommendations of the Truck Manufacturer.
13. Not Enough Air Flow Through Radiator Because of Restriction in Engine Compartment... The air flow through the radiator comes out of the engine compartment. Make sure the filters, air conditioners and similar items are not installed in a way which prevents free flow of air into and out of the engine compartment.
14. High Outside Temperature... When outside termperatures are too high for the rating of the cooling system, there is not enough temperaturedifference between the outside air and coolant temperatures. To get beter cooling, use the truck in a lower gear.
15. Operation at High Altitude.,, The cooling capacity of the cooling syste
m goes down as the truck is used at higher altitudes.A system, under pressure, large enough to keep the coolant from boiling must be used.
16. Engine Used in a Lug Condition."Lugging'
(when the truck is used in a gear too high for engine rpm to go up as accelerator pedal is pushed farther down, or when the truck is used in a gear where engine rpm goes down with accelerator pedal at maximum travel) the engine causes the engine rpm and fan rpm to be low.
This low rpm causes a reduction in air flow throughthe radiator, and a reduction in the flow of coolant through the system. This combination of less air and less coolant flow during high input of fuel will cause above normal heating.
17. Air Inlet Restriction.. Restriction of the air coming into the engine causes high cylinder temperatures and more than normal amount of heat to pass to the cooling system. Check for a restriction with a water manometer or a vacuum gauge(which measures in inches of water). Connect the gauge to the engine air inlet between the air cleaner andthe inlet to the turbocharger. With gauge installed, run engine at full load rpm and check the restriction. Maximum restriction of air inlet is 635mm(25 in) of water. If the indication is higher than the maximum permissible restriction, remove the
dirt from the filter element, or install a new filter element and check the restriction again. If the indication is stil too high, there must be a restriction in the inlet piping.
18. Exhaust Restriction.. Restriction in the exhaust system causes high cylinder temperatures and more than normal amount of heat to pass to the cooling system. To see if there is an exhaust restriction, make a visual inspection of the exhaust system. Check for damage to piping or for a badmuffler. If no damage is found, check the system for back pressure from the exhaust(pressure difference measurement between exhaust outletand atmosphere). The back pressure must not be more than 1016 mm (40 in) of water. You can also check the system by removing the exhaust pipes from the exhaust manifolds. With the exhaust pipes removed, start and run the engine to see if the problem is corrected.
Not Correct..… Check and make necessary adjustments as per Testing and Adjusting section of this Service Manual.20. Transmission Problems... Power-shift or automatic transmissions that are cooled by the engine cooling system can cause above normal heating if they are out of adjustment or not working cofrectly. See the transmission Service Manual for the correct adjustments.
19.Fuel Injection Timing Not Correct...Check and make necessary adjustments as per Testing and Adjusting section of this Service Manual.
20.Transmission Problems..Power-shift or automatic transmissions that are cooled by the engine cooling system can cause above normal heating if they are out of adjustment or not working correctly.See the transmission Service Manual for the correct adjustments.
