Hello and I want to apologize for my bad English. Is it normal for the open cap of the tank to be vacuum? O3 1.6 tdi 105 hp

Do you mean, “Is it normal for air to rush in when the cap is opened?”

 

If so, then yes. It is normal.

Hello, I want to apologize again for my bad English. Fuel tank remains under vacuum, and when the cap disengages, it emits a sound "ssssssss" : D

Just now, Naiko said:

Hello, I want to apologize again for my bad English. Fuel tank remains under vacuum, and when the cap disengages, it emits a sound "ssssssss" : D

That’s normal, nothing to worry about

Hello, and don't apologise - it's good to have a foreign member so don't worry!

 

Answer again is yes, my 2014 VRS TSI does exactly this - open the fuel cap and in rushes air making a woosh sound.

I have never heard a woosh sound.

Thank you guys,  you helped me a lot while reading the forum. I thank you all very much . 

can anyone tell me what is surrounded by black?

and what is the scheme of the vent?

Because the fuel can not leak if the vehicle is in an accident, maybe on its roof.

But fuel expends as ambient temps and pressures change, there is pressure so a release / venting system is required.

(some people vent fuel tanks to get more fuel in to extend their range, this needs doing with care and using the extra fuel before parking, and then their are risks depending 

on the system on the vehicle, also if a diesel or petrol.)

12 hours ago, toni8b said:

I have never heard a woosh sound.

It's more noticable when you're low on fuel say less than 50 miles left in the tank. And yes it does sound like a WHOOOOOSSSHHHH!

hmm there is a logic to hear it then as we go to charge and the fuel has fallen ... but most probably not vacuum but pressure.

2 hours ago, shyVRS245 said:

It's more noticable when you're low on fuel say less than 50 miles left in the tank. And yes it does sound like a WHOOOOOSSSHHHH!

I usually fill up with fuel well before reaching low fuel warning, so maybe this is the reason.

Hello, I disassembled the backbone today and released the well of the lawn to get to the vent, and I realized it was not a vacuum but a pressure, the vent only works in one direction, that is, when the car is overturned in an accident, it prevents fuel leakage type vent can only be obtained pressure and vacuum. Greet friends.