Dear friends,
There are various reasons of overheating but lets first know about the components and working of the cooling system.
The cooling system consists of the radiator, radiator cap, radiator fan, hoses, the degas tank, coolant and in the engine side the water pump, water pump pulley, the thermostat valve and the water channels to flow the coolant in the engine.
The electronic components are the fan control thermostat, ECT sesnor(forMPFI) fan relay, and the temperature sensor which is connected to the temperature meter, and the temp meter itself.
1. Coolant Flow
The coolant is flown continuously by the water pump which is driven through a pulley and belt. (Check the pulley and the condition of the belt also check for any slippage or tightness in water pump rotation)
The coolant flows through the engine, intake manifold and the head. (If the car has heater option, the coolant goes to the small core in the cabin too.) The head gasket prevents any compression, oil or coolant leak while the engine is in operation. (Check the head gasket that if its blown/deteriorated this will cause oil-coolant mix and heat the car also this will lead to compression loss ) I suffered oil leaks from the head gasket as the head was in bad condition and I used it after lathe work, later I replaced with different head.
The coolant then flows to the radiator which is then cooled by forced air from fan and then again is sent towards the engine.
2. Radiator
(There are two types of radiator aluminum and copper. The copper radiator is repairable and does not burst under high pressure but it takes time to cool down. The aluminum radiator is a bit tough to repair but its advantage over copper is that it cools down faster. The radiator cap also plays a major role here) as it builds up and keeps a constant pressure in the radiator which prevents the water from boiling. The excess water/pressure is transferred to the degas tank through the thin pipe, the pressure releases from the small hole in degas tank cap and water goes in the tank which is again sucked back in rad when the pressure decreases in radiator. Check the radiator cap spring and the rubbers for corrosion. Many mechanics do remove the rubber Also check the degas tank for any cracks or leaks.
3. Thermostat Valve
The role of the thermostat valve is to restrict coolant flow during cold start so that the engine can attain minimum operating temperature. after the engine reaches that stage, the valve opens and coolant flow starts.
Many a times the valve is clogged due to impurities in water thus restricting flow. This thing can be removed and will not harm the engine.
4. The electronic components
a. There are two types of fans 80W and 120W for AC models, with time the fan bearing may tighten or lose too much which may cause loud noise from fan or tighter thus slower fan movement. Check fan movement and compare with other M800s fans
b. The electronic thermostat which turns the fan on/off. This may become faulty by aging and may cause delayed start of fan thus causing heating A direct bypass switch can be connected to the relay so that fan can be started when we see temp rise and fan is not working. or else change the thermostat with only MGP or Minda Thermostat. For the MPFI models the ECT sensor sends signal to the ECM to start the fan. In emergency cases if the ECT sensor connector is removed, the fan starts automatically.
c. The temperature sensor for the meter or the meter itself fails rarely but can fail.
d. If the fan relay is old the contacts or terminals may have corroded thus giving less power to fan. Also faulty alternator or low charged battery may be a cause for slow fan. Thus all these need to be checked.
5. Cleaning
The cooling system including the radiator must be cleaned thoroughly. The engine side should be cleaned using pressurized water pipe inserted in one hose and observing the water coming out of bottom hose for any head gasket or metal chips.
The copper radiator can be cleaned by professionals using acid. Then using tweezers all the fins need to be straighten for maximizing air flow (this requires lots n lots of patience)
All hoses should be inspected for any cracks and then cleaned from inside. the thin degas tank hose is many a times neglected. The degas tank should also be cleaned using soapy water and all dirt inside should be removed. (Do not forget to remove all soap deposits from inside the tank)
USE ONLY DISTILLED WATER AND COOLANT MIXTURE. As the normal tap water's impurities cause the water to boil.
There are few more things which will be covered later . . .
There are various reasons of overheating but lets first know about the components and working of the cooling system.
The cooling system consists of the radiator, radiator cap, radiator fan, hoses, the degas tank, coolant and in the engine side the water pump, water pump pulley, the thermostat valve and the water channels to flow the coolant in the engine.
The electronic components are the fan control thermostat, ECT sesnor(forMPFI) fan relay, and the temperature sensor which is connected to the temperature meter, and the temp meter itself.
1. Coolant Flow
The coolant is flown continuously by the water pump which is driven through a pulley and belt. (Check the pulley and the condition of the belt also check for any slippage or tightness in water pump rotation)
The coolant flows through the engine, intake manifold and the head. (If the car has heater option, the coolant goes to the small core in the cabin too.) The head gasket prevents any compression, oil or coolant leak while the engine is in operation. (Check the head gasket that if its blown/deteriorated this will cause oil-coolant mix and heat the car also this will lead to compression loss ) I suffered oil leaks from the head gasket as the head was in bad condition and I used it after lathe work, later I replaced with different head.
The coolant then flows to the radiator which is then cooled by forced air from fan and then again is sent towards the engine.
2. Radiator
(There are two types of radiator aluminum and copper. The copper radiator is repairable and does not burst under high pressure but it takes time to cool down. The aluminum radiator is a bit tough to repair but its advantage over copper is that it cools down faster. The radiator cap also plays a major role here) as it builds up and keeps a constant pressure in the radiator which prevents the water from boiling. The excess water/pressure is transferred to the degas tank through the thin pipe, the pressure releases from the small hole in degas tank cap and water goes in the tank which is again sucked back in rad when the pressure decreases in radiator. Check the radiator cap spring and the rubbers for corrosion. Many mechanics do remove the rubber Also check the degas tank for any cracks or leaks.
3. Thermostat Valve
The role of the thermostat valve is to restrict coolant flow during cold start so that the engine can attain minimum operating temperature. after the engine reaches that stage, the valve opens and coolant flow starts.
Many a times the valve is clogged due to impurities in water thus restricting flow. This thing can be removed and will not harm the engine.
4. The electronic components
a. There are two types of fans 80W and 120W for AC models, with time the fan bearing may tighten or lose too much which may cause loud noise from fan or tighter thus slower fan movement. Check fan movement and compare with other M800s fans
b. The electronic thermostat which turns the fan on/off. This may become faulty by aging and may cause delayed start of fan thus causing heating A direct bypass switch can be connected to the relay so that fan can be started when we see temp rise and fan is not working. or else change the thermostat with only MGP or Minda Thermostat. For the MPFI models the ECT sensor sends signal to the ECM to start the fan. In emergency cases if the ECT sensor connector is removed, the fan starts automatically.
c. The temperature sensor for the meter or the meter itself fails rarely but can fail.
d. If the fan relay is old the contacts or terminals may have corroded thus giving less power to fan. Also faulty alternator or low charged battery may be a cause for slow fan. Thus all these need to be checked.
5. Cleaning
The cooling system including the radiator must be cleaned thoroughly. The engine side should be cleaned using pressurized water pipe inserted in one hose and observing the water coming out of bottom hose for any head gasket or metal chips.
The copper radiator can be cleaned by professionals using acid. Then using tweezers all the fins need to be straighten for maximizing air flow (this requires lots n lots of patience)
All hoses should be inspected for any cracks and then cleaned from inside. the thin degas tank hose is many a times neglected. The degas tank should also be cleaned using soapy water and all dirt inside should be removed. (Do not forget to remove all soap deposits from inside the tank)
USE ONLY DISTILLED WATER AND COOLANT MIXTURE. As the normal tap water's impurities cause the water to boil.
There are few more things which will be covered later . . .