So last night, two days after examining one spark plug and putting it back in, I noticed a hissing sound from the front of the car. This hissing goes away completely when I press the clutch pedal in. What is it? Could it be connected to me opening the spark plug and putting it back in? I read somewhere about a common clutch bearing problem but I thought that it might be connected to me removing the spark plug, since I didn't notice it before. The car is a 2012 Citroen C1 (similar to Toyota Aygo and Peugeot 107)

P.S the car has only done 50,000km.

Thanks so much,


  • Could it be a small leak in your clutch somewhere? When pressing the clutch the pressure gets relieved making it so it does not force fluid out. Do you notice any leakage from the car after a while? Also have you tried locating the sound?
    – Granny
    Dec 20, 2017 at 8:44
  • I don't think there is a leak, everything is dry on my garage's floor. Couldn't it be connected to me opening the engine and removing the spark plug? I did it 3 times, because I was worried of over tightening the spark plug. After the first time I removed and put the plug back I didn't notice any noise, just after the third time, but also not directly after. Dec 20, 2017 at 9:41
  • Its wierd because pushing in your clutch vs neutral is the same thing. Your engine isnt making any revs. Im not a mechanic or anything but i love cars. But this seems to be something related with your clutch itself.
    – Granny
    Dec 20, 2017 at 10:08
  • Welcome to Motor Vehicle Maintenance & Repair! The two things (spark plug & clutch) are going to be unrelated. I'd suggest either the noise was there before (maybe just now is a bit louder) and you didn't notice it (you gained a heightened awareness because you did something to the vehicle), or it's just pure coincidence. If the car only has 50,000km on it, I'd be hard pressed to say what it might be, unless it's a faulty throwout bearing ... but they should last a lot longer than 50kkm. Dec 20, 2017 at 12:35
  • Thanks so much for the assistance and warm welcome! I think you're right. Today when I left university there was no noise, but when I arrived home to my garage, after 30km it was there again. Dec 20, 2017 at 14:52


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