2005 F/L 3.0diesel hissing
 

Hi all. I've just bought my 4th X5. I've had a Japanese imported 4.4 2001 model, 2003 4.6is, and two facelifted 3.0d models which I have to say have been by far the best. Both of them I have had remapped to develop 600nm and 200kw.

I'm having an issue with this one though, it appears to sound like an exhaust leak at idle and then under any acceleration (gets louder with more pedal) is a very loud hissing noise like air or boost is escaping. It doesn't to appear to have lost any power however.

Is this a common problem?

Just wondering if this is in the right column?

The 3.0D engine has a a weak exhaust manifold which can lead to cracking if you EGTs(exhaust gas temperatures get too high).With a re-mapped car,this is aggravated,unfortunately!

Get your head under the bonnet ,next to the turbo side and get someone else to rev the car ,and see if you can hear the hissing or smell exhaust gases.

If the hissing isnt the exhaust,it be could be the turbo hissing/whistling.

Hissing noise can also be a very small vaccum leak which isnt yet affecting performance very much .

BMW have looked at if briefly and think it's something else. One thing I forgot to add is that under hard acceleration the noise almost dissapears, but normal acceleration it is most audible.

Bump much?

So what do "Bmw" think it is,then?..They completely put aside all my previous suggestions?

I am a bit confused now ,when you say that noise almost disappears under hard acceleration,when on your opening post ,you said this,... "it appears to sound like an exhaust leak at idle and then under any acceleration (gets louder with more pedal) is a very loud hissing noise like air or boost is escaping"

Trying to help you ,mate ,but difficult when you being contradictive!
Keeps us posted to what "Bmw " say, please

Hello, I have the same problem of a hissing noise on my 3.0d 2005 e53.
I have just replaced the exhaust manifold because mine was broken. I thought that the problem was fixed but the noise is still in the motor. This noise is only when the car is pushing from 2500 to 3000 rpm. If I push down full throttle the motor sounds OK. I have changed too the flexible exhaust.
I don't know where is the problem. Any idea?

Thanks and kind regards,
Jon

The hissing problem has developed on my car also now. It seems to go away over about 3k rpm. I think there is also more lag now at lower revs. I haven't got round to changing the vacuum hoses yet but I think that may be the problem even though there is no obvious leak. I have done a small test of disconnecting the vacuum hose which goes from the turbo to the plastic unit on the left of the engine. The hissing goes away but then there is no turbo boost... so maybe it's the turbo itself ? or the actuator ?

my car is also remapped so hopefully its not the manifold :/

There are some o-rings (or something like that) at the turbo pipes from the intercooler. Have you checked these?

Only recently started to notice the hissing so haven't had a chance to properly look yet but will keep that in mind, Thanks

ps. did the OP find out what the hissing was ??