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Old 2nd March 2010, 15:42   #1
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Default M800 - Fan runs at high speed

I own a Maruti 800 MPFI 2009 Model and have done 12K kms and 4 months old now. I frequently do long trips. Sometime i notice that after driving for nearly 400+ kms , reach home, switch off the ignition and after 5-10 mins, again start the engine, the fan blows at very high speed and the engine also runs at high speed.

Is this normal or any issues. Please help
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Old 2nd March 2010, 16:42   #2
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This tends to happen when the engine is restarted before it has time to cool down completely.

The thermostat, after it has remained switched off for some time, is designed to expect a cold engine.

When it does not, it starts to work overtime.

Nothing to worry, methink.
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Old 2nd March 2010, 16:46   #3
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Quote:
Originally Posted by skdking View Post
This tends to happen when the engine is restarted before it has time to cool down completely.

The thermostat, after it has remained switched off for some time, is designed to expect a cold engine.

When it does not, it starts to work overtime.

Nothing to worry, methink.
skdking, Thanks for your advice. I'm now relaxed
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Old 2nd March 2010, 17:19   #4
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Its always better to idle the car for a short while (after long runs/high revs) and let the radiator fan run one cycle before you switch the engine off.
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Old 2nd March 2010, 17:30   #5
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Particularly with M800, I've heard that fan noise when the vehicle is put into neutral.
It's an expected behavior from the car. There's nothing to worry about.

@Jaggu: I second that.
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Old 2nd March 2010, 18:05   #6
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while its normal for long driven vehicle to run Radiator Fan, it would be much better to get the Coolant and Sensor checked so there's no issues to worry about.
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Old 2nd March 2010, 18:49   #7
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Default Absolutely normal behaviour

While I must state that your car is behaving absolutely normally I suggest you coast home the last 2 to 3 kilometers. By this I mean that you use the accelerator to the bare minimum in the highest possible gear without lugging the engine. I am sure you will not have this mild irritant of the fan switching on when the engine is restarted once you practice this coasting home.

This mode of coasting home is especially helpful when using turbocharged cars as its mandatory even if mentioned otherwise on websites to spin down the high revving turbo impeller before shutting down the engine of turbo charged cars.
In all my cars I have done this even though they were not turbo charged but I do it religiously now since I have recently bought myself the Chevy Cruze. The last 3 kilometers is driven home with engine below 1200 rpm which is ample time for the turbo to spin down to acceptable levels.
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Old 2nd March 2010, 22:35   #8
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NIce! thermostat expects engine to be cold! when did they start expecting??

Thermostat is a simple BI metallic contact ,hotter it gets closer these contacts move in,at a certain temp they come together and complete the circuit and makes the fan run!
Also there are no Multi speed radiator fans employed in maruti 800,either it spins at set speed or it does not spin atall,there is nothing like fan running hyper fast! it might just be your own senses telling you that there is an abnormal sound from car because you hear the fan running even when the vehicle is not started( ignition on position) after your long haul back, where as, when you start car in morning or after a long break you do not hear the cooling fan working,so you kind of get used to that quite start procedure.
i guess it is quite normal for cooling fan to work after a 400km trip,just because the thermostat is still immersed in hot coolant!
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Old 3rd March 2010, 10:04   #9
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Jaggu
VTEC_Rocks
ghpk
drpullockaran
dustom_99

Thanks a lot for your guidance & detailed explanation. From your views, i understand this is normal in M800 and not to worry about. I feel relaxed now and thank you all for taking time to clarify me.
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Old 3rd March 2010, 15:58   #10
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Quote:
Originally Posted by dustom_99 View Post
NIce! thermostat expects engine to be cold! when did they start expecting??
I rest my case, m'lord.
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Old 3rd March 2010, 23:28   #11
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Just to reiterate further - it is normal because once you shut down the engine, there is no coolant flow - the radiator fan is linked to the ignition switch. Therefore the coolant around the engine will start to heat up abnormally, triggering the thermostat, but since the power to the radiator fan is off, the coolant can't be circulated and so when you do finally switch back on immediately, the fan kicks in immediately.
Added to this the air flow over the radiator fins when the car is moving and consequently the lack of it when the car is at a stop.
good idea as suggested above - let the fan start and stop after you bring the car to a halt for one cycle.
On newer age cars though - like my Octavia, the fan normally starts on it's own, irrespective of whether the key is in ignition or not. So it's quite normal to hear the fan start and stop when I'm out the car and just getting into the house.

the fan not starting - now that would be a problem!
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Old 4th March 2010, 09:30   #12
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Quote:
Originally Posted by Otto View Post
Just to reiterate further - it is normal because once you shut down the engine, there is no coolant flow - the radiator fan is linked to the ignition switch. Therefore the coolant around the engine will start to heat up abnormally, triggering the thermostat, but since the power to the radiator fan is off, the coolant can't be circulated and so when you do finally switch back on immediately, the fan kicks in immediately.
Added to this the air flow over the radiator fins when the car is moving and consequently the lack of it when the car is at a stop.
good idea as suggested above - let the fan start and stop after you bring the car to a halt for one cycle.
On newer age cars though - like my Octavia, the fan normally starts on it's own, irrespective of whether the key is in ignition or not. So it's quite normal to hear the fan start and stop when I'm out the car and just getting into the house.

the fan not starting - now that would be a problem!
Great Explanation. Thanks Otto
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