Detectives! Please help debug XC90 engine noise (with video)

[joelq]

Hi all -

We have a 2004 XC90 with ~122K miles. About a month ago, it started making a loud, cyclical, squeeking noise when started cold. The noise only happens for a few seconds, and only when the engine is cold. Once the engine is warm, subsequent starts don't generate a noise. The car has to be sitting for several hours for it to reoccur at start.

The noise changes in pitch along with the RPMs of the car, so when I rev the engine, the noise rises in pitch.

I recorded a short video to hopefully give clues. The video has three consecutive starts of the engine, and you can see how the noise lessens as the engine warms after each start.

Any ideas?

Watch video here: http://vimeo.com/12617124

Thanks!

[ecbsykes]

That sounds like a belt is going bad/rubbing on something. Check the serpentine and timing belts for damage or signs of rubbing. The sound might be going away because the belt then stretches/warms up a little as you run the car.

[Volvodownunder]

Hi - I agree with the previous suggestion of it being related to fan etc belts. I have experienced a similar thing with numerous vehicles over the years.
My suggestion is if you determine it as the problem - replace all belts

[joelq]

Hi all -

Just reviving this thread to see if anyone has any other suggestions. Since my original post, I've had the timing belt and pulleys replaced. Noise is still there. Since the problem takes a long time to reproduce (have to wait until the engine is cold), they suggested I wait until the sound happens more frequently, and they can try and search for the noise again.

I had to take the car into the dealer for the fuel pump bulletin, so I went ahead and had them look into the noise as well. They really didn't get very far, and eventually suggested the same thing my mechanic suggested above.

In the meantime, the noise hasn't really gotten worse (or better). One thing I'm wondering about - you know how, when the engine is started cold, it will rev up to the 1500s for a few seconds, before dropping down to 1000, then down to 750 RPMs? The noise only happens when the car is revving at the 1500 level. Mind you, once the engine is warm, the noise no longer happens, even if I manually rev the engine up.

What controls this? Is it strictly the computer opening the throttle to reach RPMs in the 1500s? Or is there some mechanism that engages to get this to happen? I'm suspecting that whatever that mechanism is is causing the noise.

Any ideas? Thanks!

[dmd]

All computer controlled, computer just says the idle speed should be 1500 and that
is what it goes to.

[jpaeth]

What engine does your xc90 have??

[joelq]

What engine does your xc90 have??

Hi -

My XC90 has the 2.5T engine.

[joelq]

Just closing the loop on this one, as I finally got the problem fixed last week! The noise was coming from a leak where the exhaust intake attached to the engine. There was soot all over the spot where the leak was.

So last week, I finally take the car in to get this fixed. I was warned that labor would be relatively expensive for this repair, so I had to wait a bit to get it done. :-) Well, as my mechanic started taking parts off, he finally found out why the gasket blew - one of the studs/bolts had broken off, so the seal wasn't as good as it should be. They had to spend a couple extra hours getting the broken bolt out of the head. :-/ After a couple hundred $ more in labor, the problem is finally fixed!

I'd forgotten how peppy the 5-cylinder could be!

[angelvolvo760]

Just closing the loop on this one, as I finally got the problem fixed last week! The noise was coming from a leak where the exhaust intake attached to the engine. There was soot all over the spot where the leak was.

So last week, I finally take the car in to get this fixed. I was warned that labor would be relatively expensive for this repair, so I had to wait a bit to get it done. :-) Well, as my mechanic started taking parts off, he finally found out why the gasket blew - one of the studs/bolts had broken off, so the seal wasn't as good as it should be. They had to spend a couple extra hours getting the broken bolt out of the head. :-/ After a couple hundred $ more in labor, the problem is finally fixed!

I'd forgotten how peppy the 5-cylinder could be!

my 2005 Volvo xc90 t6 is having a similar problem sounds like a belt is making the noise but how can I find out exactly without hiring mechanics just to know

[bugeye]

Suggest sticking the end of a piece of tubing to your ear. Try about 1/2" diameter. Start the engine and move the other tubing end around trying pulleys, alternator, power steering pump, etc listening for the noise. Don't be afraid to take off the timing belt cover. Just watch your fingers and hose while the engine is running. A long screwdriver touching parts and against you ear might work. Harbor fright has a mechanics stethoscope. I never tried one, but is cheap with ok reviews.