Hissing after the engines stopped

[jshodgson]

After I turn off my engine after a short run there is a hissing noise that is coming from the centre of the bulk head (there are two rubber pipes which feel hot). The hissing goes away after a minute or so.

I have recently had my radiator taken off and have noticed my temperature never moves off 90degrees also.

Anyone have any ideas>????????

Many thanks, James

1998, 1.9 TDi A4 Avant 207,000 miles

[Huweth]

I have the same hissing with my Passat TDI. I think it's due to pressure release from the aircon system. We should both try driving without aircon and see if the noise is still there. Then report back here.

I'll do it tomorrow...

P.s. My temp never moves from 90 either. Either it's a problem or just an idiosyncrasy due to the fact that the TDI's are extremely thermally efficient.

[jshodgson]

Well it worked on mine. The hissing stopped when I didn't use the aircon. Do you think this is a sign of a problem wheich would need to be looked at?

[Huweth]

Mine stopped hissing too. Either we both have the same problem, or it is perfectly normal. Perhaps it is a valve that releases pressure when the system turns off. I simply don't know.
I'm just going to carry on as normal until it breaks (or not)!

If anybody else's car does this, or not, please let us know!

[stuart]

My current car does the same, as did my last one... can hear it after I turn the engine off... must be a standard feature of AC ;)

Stuart

[onzarob]

Mine makes the same noise and I found this which deatils how to bleed the cooling system properly.

http://www.bba-reman.com/content.aspx?content=hints_and_tips_audi_strange_n oises_and_vibrations

Haven't tried it yet but seems a common problem.

Rob :D

[gwentaudi]

Lads,
I sell A4 avant tdi for a living and every one I've ever had does it so I think we can assume it is normal.
John ( Gwentaudi )

[Golfer7]

The noise is from the air con. system and standard as the Audi gent said, not a problem, just gasses in the system making noise...

[mikecmr]

happened on my s4 thought i had a leak so went to audi and said it was normal what normal cars make this noise god damn audi rahhh

[Boardboy]

I drive a ford van at work and it gurgles and hisses from new!!
Boardboy

[new to vw]

my 99 passat does same did it from when i got it....my theory is if it aint broke dont mess with it
lee

[guyg]

The noise is from the air con. system and standard as the Audi gent said, not a problem, just gasses in the system making noise...

When the engine is switched off after the aircon has been running, you can simply hear compressed liquid refridgerant changing back to its gaseous state

As Golfer 7 states, this is normal and expected - if your's [B]doesn't do this then something is wrong...

Cheers

Guy