Engine Heating

[monty]

Hi Guys !

Recently when I was on an outstation trip the car's engine heat level went up and the radiator water started boiling. Took it to a garage and was told that there were a couple of causes.

What was found was a leak in one of the water hoses and also the radiator fan didn't seem to switch on/off at appropriate intervals to keep the engine cool. The problem with the latter was found to be with the thermostat which did not pass the required current to the radiator fan to switch on when required.

Can this be a case where the leak in the water horse might have caused the thermo to run dead in passing the current? or is it that the thermo went dead first and the horse blew up due to over heated water running through? I currently have the fan working on direct current so it's switched on all the time (which I guess is not good for the fan).

Will replacing the thermostat solve the problem ?

Just thought of getting some advice from you guys on what to look for before taking it to the garage ppl.

Thanks Guys !

Monty

[jaga]

Acutually this is a very complicated case, as you said it could happen either way. Once you identify the problem you have to fix the thermo stat switch (censor which give power to the fan).

This could happen due to following possible reasons,

1 Due to a hose leak.

2. Defectiveness of the cooling fan.

3. Defectiveness of the water pump.

4. Radiator block or fins are covered with foreign materials from out side.

5. Water level of the radiator has gone down due to evaporation.

6.Tubes inside the engine blocks get cholked.(Very rear)

Check the water pump and if it works properly I suggest you to clean up the carb.(It is not much expensive and you can get it done at panchikawatte also). Make sure to replace the thermostat (Better if you can find a genuine one) other wise your cooling will never long last.

[The Don]

Hi Guys !

Recently when I was on an outstation trip the car's engine heat level went up and the radiator water started boiling. Took it to a garage and was told that there were a couple of causes.

What was found was a leak in one of the water hoses and also the radiator fan didn't seem to switch on/off at appropriate intervals to keep the engine cool. The problem with the latter was found to be with the thermostat which did not pass the required current to the radiator fan to switch on when required.

Can this be a case where the leak in the water horse might have caused the thermo to run dead in passing the current? or is it that the thermo went dead first and the horse blew up due to over heated water running through? I currently have the fan working on direct current so it's switched on all the time (which I guess is not good for the fan).

Will replacing the thermostat solve the problem ?

Just thought of getting some advice from you guys on what to look for before taking it to the garage ppl.

Thanks Guys !

Monty

Hi Monty,

You would have to tell us your vehicle make and model for somebody to give you a vehicle specific answer but, I hope my explanation helps.

The circuit that operates the fan actually works on the fail safe mode.

If the thermostat fails for some reason the circuit should activate the fan irrespective of the temperature and thus protect the engine of the car.

So if the fan didn't come on at the correct temperature apart from checking the thermostat you should also check the relay or the circuit which controls the fan.

And like jaga says you should also check the thermostatic valve and also the water pump to see if they are working as they should. and also clean up the cooling system and replace the coolant.

Edited April 3, 2008 by The Don

[monty]

Acutually this is a very complicated case, as you said it could happen either way. Once you identify the problem you have to fix the thermo stat switch (censor which give power to the fan).

This could happen due to following possible reasons,

1 Due to a hose leak.

2. Defectiveness of the cooling fan.

3. Defectiveness of the water pump.

4. Radiator block or fins are covered with foreign materials from out side.

5. Water level of the radiator has gone down due to evaporation.

6.Tubes inside the engine blocks get cholked.(Very rear)

Check the water pump and if it works properly I suggest you to clean up the carb.(It is not much expensive and you can get it done at panchikawatte also). Make sure to replace the thermostat (Better if you can find a genuine one) other wise your cooling will never long last.

Thanks jaga ! Yes, as you noted it's important that I look for a genuine thermo.

[monty]

Hi Monty,

You would have to tell us your vehicle make and model for somebody to give you a vehicle specific answer but, I hope my explanation helps.

The circuit that operates the fan actually works on the fail safe mode.

If the thermostat fails for some reason the circuit should activate the fan irrespective of the temperature and thus protect the engine of the car.

So if the fan didn't come on at the correct temperature apart from checking the thermostat you should also check the relay or the circuit which controls the fan.

And like jaga says you should also check the thermostatic valve and also the water pump to see if they are working as they should. and also clean up the cooling system and replace the coolant.

Good point Don. Didn't know that. If that is how it is supposed to operate then it can also be a case with the circuit relays. Will have these points checked. Btw...mine is a 96 EK3.

Thanks Don!

[maithri]

I beg to contradict,

I have not yet come across a car that has the cooling fan wired in a fail safe mode. The thermo switch is a mercury capsule that expands due to heat and bridges the contact to switch the cooling fan relay(cut out) that then switches the fan on. Very difficult to design a fail safe for this.

To the problem-first cure the leak, then see how the car's cooling system work, switch the fan on manually as soon as the temp guage passes the half way mark with the car idling, see if this brings the temperature down, switch the fan off as soon as the needle drops below half, repeat the process, if this works ok go and buy a new thermo switch, these fail often so no need to go looking for why it happened same as a blown light bulb! When you fit the new switch make sure the fan cuts in to prevent the coolant getting too hot-not necessarily at halfway point and switches off as well-if this works all is well happy motoring.

Maithri.

[Grand Civic]

if it is a Honda , Take it to Upul at malabe . he will sort out any honda issues.

[The Don]

I beg to contradict,

I have not yet come across a car that has the cooling fan wired in a fail safe mode. The thermo switch is a mercury capsule that expands due to heat and bridges the contact to switch the cooling fan relay(cut out) that then switches the fan on. Very difficult to design a fail safe for this.

To the problem-first cure the leak, then see how the car's cooling system work, switch the fan on manually as soon as the temp guage passes the half way mark with the car idling, see if this brings the temperature down, switch the fan off as soon as the needle drops below half, repeat the process, if this works ok go and buy a new thermo switch, these fail often so no need to go looking for why it happened same as a blown light bulb! When you fit the new switch make sure the fan cuts in to prevent the coolant getting too hot-not necessarily at halfway point and switches off as well-if this works all is well happy motoring.

Maithri.

In the old Mazda station wagon If I'm not mistaken if I took the connector out of the thermostat the fan would come on. I'm not sure exactly how the system worked (can't remember) but I read in a magazine that this was a fair safe the manufacturer had built in to the system.

but you are the expert.

[jaga]

if it is a Honda , Take it to Upul at malabe . he will sort out any honda issues.

Bro if you don't mind could you tell me the Upuls location at Malabe.

Thanks.

[maithri]

Don, I am sure it is a simple thing to do on an ecu controlled fan like in a Peugeot where any incoherrant temperature signal is replaced with a default value so the car can run without extreme problem but Mazda's are not that common in the UK as you know so I cant recall seeing one like the one you mention. Still if such a system was in place we will have far less breakdowns on our motorways during traffic jams fro over heating.

[monty]

Don, I am sure it is a simple thing to do on an ecu controlled fan like in a Peugeot where any incoherrant temperature signal is replaced with a default value so the car can run without extreme problem but Mazda's are not that common in the UK as you know so I cant recall seeing one like the one you mention. Still if such a system was in place we will have far less breakdowns on our motorways during traffic jams fro over heating.

Hi Guys,

Replaced the thermo and all good now. Pretty straight forward job it was at the end

maithri, Don, jaga, Grand Civic...Thank you all guys !

monty

[harshansenadhir]

I beg to contradict,

I have not yet come across a car that has the cooling fan wired in a fail safe mode. The thermo switch is a mercury capsule that expands due to heat and bridges the contact to switch the cooling fan relay(cut out) that then switches the fan on. Very difficult to design a fail safe for this.

To the problem-first cure the leak, then see how the car's cooling system work, switch the fan on manually as soon as the temp guage passes the half way mark with the car idling, see if this brings the temperature down, switch the fan off as soon as the needle drops below half, repeat the process, if this works ok go and buy a new thermo switch, these fail often so no need to go looking for why it happened same as a blown light bulb! When you fit the new switch make sure the fan cuts in to prevent the coolant getting too hot-not necessarily at halfway point and switches off as well-if this works all is well happy motoring.

Maithri.

well i'm not too sure whether i've got it wrong but in my 406 it has a fail safe and it worked few times as well. so after knowing that i use this method to check both radiator fans. the moment i pull out the connection from the sensor both radiator fans engage in full speed (2nd stage).