HAVE A 2004 XC90. STARTING HEARING A HISSING SOUND WHEN I TAKE MY FOOT OFF THE ACCELERATOR. IT GOES AWAY IF I PUT THE CAR IN NEUTRAL. THE SOUND BEGAN AROUND 49,000 MILES AND SEEMS TO BE GETTING LOUDER. IT IS ONLY NOTICEABLE AT SPEEDS GREATER THAN APPROX. 40 MPH. ANY IDEAS?

 

Which engine do you have in there?

Is there a check engine light on?

 

T6 ENGINE; NO ENGINE LIGHT

 

Look at the plastic piping on the top of the engine good for splits.

 

Will do. It won't be until this weekend, but I'll let you know.
Thank You.

 

Sorry for the lengthy delay.
I looked at the plastic piping and found no cracks. What are your thoughts? Is it a possible indicator of the transmission going bad? Again, this noise disappears when I put it in neutral.

While I have your ear, it was recommended that I get a fuel injection cleaning and brake fluid flush. I have 55,000 miles. Are this necessary now? Will a high quality fuel injector cleaner added to my gas periodically suffice?

Thank You.

 

Since it is a T6 why not check your Turbo Hoses. They may be leaking.

 

Does the noise change with touching the brakes?

Have you had any major work done to it?


Try getting a bottle of Techron and adding it to the gas. That will work just as good.

 

In response to both s70DRIVER and TECH:

I have had a dealer check it. They claim not to hear the noise, but many passengers have.

I assume they would have checked the turbo hose. I don't know where that is located.
The only major work peformed would be right rear wheel bearing and front disc brakes.

The noise does not disappear when I apply the brakes.

The question about the brake line fluid and fuel injector cleaning was a recomendation during a routine sevice. Not as a solution to this engine hiss. (I have put a bottle of the Techron in my tank.)

I was hoping maybe you guys could give me little help so when I bring it back to the dealer, I could give them some direction.

Thanks for your thoughts.

 

Look at the floor board where the steering column goes throlugh the floor.
There is a bearing that is on the steering shaft it also slides into the boot. If that comes loose it will make a similiar noise.

 

I was thinking the same thing...


If that bearing is not properly installed in the rubber boot that goes over the steering column you will hear excessive turbo noise. Do you hear this noise while the car is in park?

 

NO. I ONLY HEAR THE NOISE WHEN I LET MY FOOT OFF THE ACCELERATOR, AND IF I THEN PUT THE CAR IN NEUTRAL WHILE I'M TRAVELING , THE NOISE GOES AWAY.

 

I own a 2004 XC90 T6 which I bought new. I've a little over 44,000 miles on the car. It has just developed the very same noise and sequence of events described here ... a loud hissing noise starts when I take my foot off the accelerator. I've had the car into my dealer twice. The first time I took it in they looked at the turbo hoses; nothing amiss. The second time they politely listened to me, then took the car out for short drive with a mechanic and a manufacturers rep. They reported back that the noise I was hearing was "normal" for the XC90.

Of course I asked why, if the sound was "normal", it hadn't been there all the time. Why had it just now started? I got a blank look and a sorry that's the way it is response. As you can imagine, I am disappointed.

One other thing I have noticed while all this has been going on ... my gas mileage has dropped.

This thread stopped in November. To those of you who wrote, were you able to solve the problem?

 

I have a similar noise (hissing) and sequence of events with the only difference that I hear it while acceletating as well, and when I take my foot off the accelerator I still hear it (sound like its coming from in front of the driver side of the vehicle), the loud hissing noise then slowly starts to wind down whilst the vehicle then automatically slowing down - no difference whether the vehicle being in "D" or "N", Whilst the vehicle is stationary no such noise can be heard in the cabin.
Please advise..

 

Has anything been figured out with this problem? I have the exact same problem as XC90Washington.