04 XC90 with 70K miles. recently I have been hearing a small dog barking sound when the car is under acceleration between 2000 and 3000 rpm. It happens in all gears, with or without AC on. I tried to isolate the sound in neutral with the car stopped, but it only barks under load while driving. I wonder if this is from the timing belt or Turbo charger.

 

I too have this same barking/groaning noise within the same rev range on my 2004 XC90 T6. The volvo dealer I bought it off tells me it is a Volvo characteristic, however there is a counterweight that can be fitted to the drive shaft to mute the noise, but this doesn't always work. In my case it didn't work.

I spoke to another dealer and they tell me that this is not a characteristic, however many T6's have been noted to have made this noise and that a counterweight sometimes stops the noise. No one is clear about what the noise is but i can tell you that mine has got louder over time, and that I have just received my second 'transmission service urgent' message. I fear the noise may be associated with the T6's notoriously faulty transmission.

Is your XC90 a T6? Let me know if you hear of or have heard any other theories.

 

Yes, It is a T6, and I am on my third transmission. Before my Audi V8's timing belt snapped, it was making some noise, I am playing it safe by replacing the Timing belt today at a repair shop.

 

The timing belt and serpentine belt were replaced and the barking sound went away.

 

I'm a 4-day-old '04 XC90 T6 owner (came from the Mercedes school of over-engineering!!) and I'm still in the learning process

I'm happy to know that the barking / groaning noise did disappear on yours but... did you experience any overheating, backfire, misfire which is natural symptoms for having bad timing belt

Regards