A4 avant 2.5tdi 02 B6 hissing noise

[H&O2008]

I have noticed over the last few days I have a hissing noise coming from the front passenger side wheel arch area anyone have any ideas what it might be. Would it be an air leak, I can hear it on tick over as well as when driving? Have not noticed lack of power, could it even be pully noise.

[mikeybutch]

Check the coolant tank cap and pipe connections

[frankc]

The front of the wheel arches house the intercoolers for the 2.5tdi so check for loose connection top and bottom and any sign of oily residue indicating a potential leak.

Does the hissing noise get louder under load?

Frank.

[H&O2008]

no not a coolant problem, intercooler pipe in the wheel arch sounds favourite at the moment as for the hissing noise if i drive with the passenger window open i can here it most of the time whilst driving

Check the coolant tank cap and pipe connections

[H&O2008]

I have had the inner wheel arch off today and there is no oil residue or any leaks that I could physically feel when the engine was running. The noise does not seam to get any louder and I have not lost any power. Maybe it is a pully noise I really now have no idea.

[mikeybutch]

Have you checked the coolant system ?.When I got my 2.5Tdi I found a slight crack in the back of the tank which couldn't be seen but could just be heard when it was under pressure

[H&O2008]

Surely if it had a crack in the tank it would be using water or over heating?

[mikeybutch]

Possibly but it was found on purchase when doing all round checks and obviously not noticed by the seller.So easy just to loosen the tank and look.Surprised to see the hairline crack but only £12 for a new one