XC90 V8 :Kind of Sizzle noise from left side of the engine

[nono7777]

Hello,

I have kind of sizzle or growling noise from left side of my XC90 V8 (2007 model year)

The noise is always here with engine cold and hot (no differences)

I have recorded the sound if it rings some bell to someone.
engine noise

Thanks for your help,
Best,

[TruckbusUK]

Sounds like a belt, had any work done recently involving fan belt/aux belt etc?

[wynnj]

Alternator pulley freewheel ?!

[nono7777]

During vacation last year the alternator has been replaced by a Volvo dealer (it fried)
The dealer told me original alternator are frequently destroyed by V8 engine because of the heat and he replaced it with a fixed model that prevent this defect (36000791)

while he replaced the alternator he also replaced belt tensioner (31216199) and belt (8653617)

I only drive 7000 km since

[TruckbusUK]

Originally Posted by nono7777

During vacation last year the alternator has been replaced by a Volvo dealer (it fried)
The dealer told me original alternator are frequently destroyed by V8 engine because of the heat and he replaced it with a fixed model that prevent this defect (36000791)

while he replaced the alternator he also replaced belt tensioner (31216199) and belt (8653617)

I only drive 7000 km since

Does that tie in with the noise starting?, could be a belt is either on its way out, or too tight, worth checking, visually on the condition if you can and the "thumb/twist" test for tightness ... not hugely accurate but will give an indication if the belts are too tight.

[nono7777]

The noise appeared very recently I will check if it is too tight, thanks

[nono7777]

Belt is on the right side of the engine and seems ok, the noise comes from the left side (driver side LHD)

I try the car this morning, at cold start no noise. The noise starts after the first acceleration and does not go away while the engine is hot (even after restarting the car)
The noise seems more related to RPM while accelerating than speed itself

More records of the noise https://photos.app.goo.gl/QqiLTGpwdBWJH2Pi7
and https://photos.app.goo.gl/62kYSmsMRiJrYX5G7

[TruckbusUK]

Listened to your clips again, and at first thought ... noisy injector, then the engine revved, and mmmm still think its a belt that's too tight or on its way out or maybe a pulley that's moving on its shaft, but if you say its coming from the other side of the engine, maybe noisy injector is right.

Can you see the pulley faces? ... if its a belt and is breaking up it will mark the pulley groove "v" much more than other pulleys the engine has ...

Intriguing ..interested to hear what the root cause is.

[nono7777]

Today trying to investigate where is the exact origin of the noise, sounds strange to me but I am pretty sure it comes from transmission, very close to the trans control unit.

Could it be a noise emitted by an "about to fail" transmission ?

[nono7777]

Very strange, I wanted to bring the car to the dealer and the noise is currently gone, even after stopping and restarting the car. Could it be another sign pointing to transmission, if it is something random ?