whining driveline noise under acceleration load only

ylwgto · Post by **ylwgto** » 02 Mar 2018, 13:34

Hi,

My 180,000 mile '04 XC90 2.5T AWD has a significantly noisy whine in the front end. Seems to originate around the driver footwell. It becomes audible from about 40mph to about 80mph, above which it seems to cease. This only manifests under acceleration and the pitch becomes higher as a function of increased speed, NOT RPM. Noise immediately goes away on deceleration. No issues with engine or transmission (that I know of) and it runs fine otherwise.

Can I rule out wheel bearing noise since it stops when I take my foot off the gas?
Can I rule out transmission b/c it's not linked to RPM?
Could it be a transfer case or differential issue?
CV joint noise (no cracked boots)?

It's loud and annoying, so any ideas?

Thanks!

Post by **FLXC90** » 02 Mar 2018, 15:39

Okay, speed not RPM, which indicates past gearbox/differential.

AWD adds components, Angle Gear is near the driver footwell. If it is low on fluid, or a bearing is failing it could be that.
Do you have any vibration? Normally CVs will give telltale clicking for outers, or roaring and a side-to-side vibration for inners.
Wheel bearings can usually be diagnosed by loading/unloading during drive. Does the noise go away or diminish if you turn the wheel for a curve or lane change?

Just saw your other post, is this only since it was hit? Could be the fender liner or something like that rubbing

ylwgto · Post by **ylwgto** » 02 Mar 2018, 18:07

Thanks for the quick reply!

Car was not hit hard, just cosmetic. Cheaper to replace doors than do body/paint work! So unrelated to that

No change in noise with turning or bumps. Angle gear sound reasonable. Can you direct me to resources for checking/changing fluid in it? Is it hard job?

Thanks!

Post by **FLXC90** » 04 Mar 2018, 09:53

Use the search functions on the forum, I believe Cn90 may have posted about it. Also check youtube. Good Luck

Post by **matthew1** » 04 Mar 2018, 10:25

2005 Volvo XC90 2.5T: ATF, Angle Gear, AOC/Rear Diff Fluid

Post by **SuperHerman** » 17 Mar 2018, 19:11

A similar post is running right now - as I stated their - check your front propeller shaft CV joint. These need to be maintained as the exhaust heat causes the grease to bake. This could be your noise source.

ylwgto · Post by **ylwgto** » 19 Mar 2018, 09:56

thanks. i will check the prop shaft

silverslug98 · Post by **silverslug98** » 22 Nov 2019, 15:25

Did you ever determine the cause of this noise? I have an 06 xc90 2.5t awd making the same type of noise. I replaced the trans with a used unit, and both old and nused one are making the same whining noise. I removed angle gear, and the noise is still there.
Using a stethoscope, it is most prevalent in the lower rear portion of the trans where the final drive is. Wheel bearings, axle shaft bearing are all quiet.
I've worked on Volvos for 30 years professionally, and have never heard one of these trans make this noise, let alone 2 in a row.