Tone from drive system after driveshaft replacement

[VolvoOutWest]

We recently had the driveshaft replaced on our 2000 Volvo V70XC wagon (due to a clunking noise when backing up). Since doing that there is a tone that occurs from under the car (it's hard to pinpoint exactly where) when the car is partially warmed up (after 5-10 minutes of town driving), usually when going around 30mph or faster. The tone volume is dependent on acceleration (accelerating or letting off the accelerator can affect how loud it is) and the period during which it comes and goes doesn't last very long maybe a few minutes, I assume until some part or fluid gets fully warmed up. Using an online tone generator I would say the tone is like a pure sine wave around 440-540Hz. Our mechanic says it could be a defective driveshaft (it was a re-manufactured one) but he didn't have any other ideas. A week or two before the transmission was flushed due to a new CV joint seal and we also got all new tires but I'm pretty sure it started after the driveshaft though it's a bit hard to reproduce so I can't be completely sure. I did read a post on here about the viscous coupling and this first generation AWD system. I'm wondering if the driveshaft replacement somehow stressed some other part of the system. The tone doesn't seem to getting worse but it is disconcerting and I don't want want to ignore something that may damage other parts. This is what the tone sounds like:

Volvo 2000 V70CX Drivetrain noise .mp3

This is the high pitched noise

(426.48 KiB) Downloaded 7 times

Thanks for any help!

[Vova585]

Welcome to the club.
It is hard to say anything without having audio of the problem for start. But from what you are describing my diagnosis is - expensive.
Do you still have your old propshaft? Where you got the current propshaft from and who did rebuild. I only know of 1 trusted name when it comes to driveshaft repair(there are probably many, but i only know 1 that I used and can recommend) -Colorado driveshaft. Now lets think about this 2000 volvo..you are in CA, if you are in a part that does not require awd, better return the driveshaft and operate in fwd mode(so much cheaper). If you need(or simply want the car to be "whole") then I would suggest to bring the car to dealer, or indy with charisEar wireless diagnostic tool that can help better pinpoint the source of problem. Vs get your old driveshaft(Hopefully you have it) rebuild by Colorado driveshaft and install back. Then you at least will know that propshaft is 95% good(even new parts are sometimes defective). But all this road is expensive and will likely be 2-3k in parts and labor(diagnostic, remove reinstall propshaft, cost of propshaft...)

[abscate]

That’s a tough one since it goes away. It might be worth getting the car up on a Dyno where you can run it and have someone listen underneath to isolate the noise…

Angle gear
Center carrier bearing
Viscous coupling
Rear differential
Exhaust?

Are the two damper boxes present on the p80 XC models ? One is in the cabin under the console. The other mounts on the body right behind the oil drain plug. They are small boxes filled with old Swedish meatball fat that absorb acoustical energy.

[VolvoOutWest]

Welcome to the club.
It is hard to say anything without having audio of the problem for start.

I have added an audio clip of the noise to my original post. You will notice a high pitched whine that comes and goes throughout the clip.

[scot850]

I think the 4 speed auto trans maintained the damper box, but the 5 speed auto does not have it.

A couple of thoughts but I would suggest Abscates' idea its the best. Get the 4 wheels in the air and use a mechanics stethoscope to listen to the follow spots:

1) Angle gear - The splines could be bad between the collar from the trans to the angle gear
2) RHF axle support bearing/carrier bearing
3) Joints in the shaft, even if it new/rebuilt to make sure the front/support/rear couplings and bearings are good.
4) Make sure the heatshields have not dropped onto the prop-shaft.
5) Check the bearing for the VC at the front of the unit
6) Check the VC unit is not humming
7) Check the rear diff for leaks and oil as well as listening to it too.

No easy solution but again fairly quick.

Neil.

[Vova585]

To my ears it is Carrier bearing noise. That high pitch whistling is somewhat typical for a worn central bearing. So where you got the driveshaft from? If it was "brand new" for $350 or something like that...

[V50M66]

Almost guaranteed to be a junk driveshaft. It's really hard (and occasionally impossible, especially on MY00) to find a driveshaft for these that doesn't suck, and most shops will put in whatever cheap garbage they can get their grubby little mitts on for extra profit. Take it back to the shop and make them warranty that driveshaft.

[rrres]

Sounds like a bearing.