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Hi guys I have a really confusing problem. During long drives, after my engine warms up my fan goes crazy to the point my side mirrors shake. Yet according to my thermostat my car is perfectly fine and has never overheated.


I even did a complete cooling system flush. Where I used a hosepipe to flush and back flush my radiator and engine block until clear water ran out on both directions, added some wynns cooling system flush  with distilled water and drained the mixture after 10 minutes of idling, added the proper coolant and changed the thermostat. I can 100% confirm that my cooling system is perfect yet still, during long drives my fan goes crazy. Is it an electrical fault of my fan or is my engine actually overheating? 


My engine sounds perfectly fine although due for an engine oil change. 


If I told you how my problems started it’ll be even more baffling. It started when I filled up a tenners worth of asda brand petrol from a near enough empty tank. A day later, I’ve been getting ignition problems, rough idle, engine knock and my FAN GOING CRAZY. After checking my manual I realised that the ASDA brand petrol had to have a lower octane rating and poor quality and was the cause for it (yes, the manual warns that petrol with crappy additives will cause those problems). I immediately then slapped in a full tanks worth of some shell v power which cured all the symptoms but the CRAZY damn fan.


What could be the problem guys? An electrical fault or my engine oil or god forbid, some nasty souvenir left by the Asda petrol? 

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  • Kifayat


  • caretakerplus


  • vwfan3


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Welcome to the Forum.


I take it that when you say " according to the thermostat", you are actually referring to the temperature gauge (which should be showing about 90°C)


I can understand poor quality petrol causing the other problems, but I believe that you have two separate problems here.

(1) I believe that you are correct when you mention an electrical problem - I would recommend that you start by checking the fan switch, which may be turning 'on' the fan when it should not be 'on'.

(2) The above does not account for the vibrations from the fan, which is possibly due to the fan blades being out of balance (due to mechanical damage maybe)

 Suggest that you examine the fan, making sure that it spins freely (for the sake of safety and because the fan runs when it shouldn't, it would pay to either disconnect the battery or remove the fan fuse before placing your fingers too close to those blades) Check also for damage to the blades.

If the fan is free when you spin it by hand, and if it tends to stop in the same position every time (suggesting that the blade at the bottom is heavier than the others) it is almost certainly out of balance.



Edited by caretakerplus
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