2010 XC70 3.2 Whine (?)

[franticvike]

I suspected wheel bearings, but just had those check out fine. Tires are about a year old, in very good condition. Thinking somewhere in the drive line but hoping to narrow it down a bit and try any easy fixes before taking it in. Just had the vacuum booster oil leak fixed and that cost quite a bit.

The sound becomes noticeable about about 50 km/hr. It's a whine (not a growl, no clunking), but not super high pitch. I would say not like an electric motor, more like a gear or bearing noise. It's slightly intermittent, but pretty well reliable at highway speeds. It seems to be connected with throttle action but not 100%. I can hear it when I'm steady on the accelerator, and particularly when coming off the accelerator at highway speed. Maybe most pronounced when off the accelerator and coming down a long highway hill (not on the brakes).

As I type this it feels like a wild goose chase, but hey, who knows. Maybe my vague description rings a bell for someone, or if not, once I get it fixed I can post the solution and maybe that helps someone down the road.

Cheers,

[vova]

Unfortunately there could be plenty of possibilities.
1.how and who checked your wheel bearings? You just jaked the car up and tried to move the wheel? Or you tried to "throw" the car from side to side while driving and there was no change in sound(usually with moving the weight of the car from side to side you will hear the difference pinpointing that it is likely wheel bearing.
2. What condition are your breaks? Check for any lines,ridges, groves on outer and inner aspect of the rotor and make sure they are smooth. After driving couple miles on highway stop and touch each wheel-accesive heat on one wheel will indicate either bearing or brake caliper issue.
3. While driving at 50kmh when you hear that noise-move gear selector into Neutral and see if there would be any change in sound. Change can possibly indicate tra Swisscom.
4. Look under the car at front diferencial/angle gear and rear haldex unit with differential. Make sure they are dry and not showing since of oil leak.
5. If all is good and you are not able to find source-pay dealer or trusted mechanic to put it on the lift and see what is going on. They should check levels of all fluids and also bearings in the driveshaft/propeller shaft and right front axle carrier bearing.
Good luck and keep us posted

[franticvike]

Thanks for the reply.

Wheel and alignment shop checked the bearings during tire rotation. Never noticed any change in the noise based on driving characteristics. Brakes are new-ish (15-20k km on them).

Took it to the transmission place (Victoria Transmission). Report back is that the read differential is toasted. He says it's a common problem on these. First I've heard about it. Quoted something like 10k parts plus labour and suggested not worth it. Based on remaining value of the car (guessing 7-9k CDN) I'd tend to agree.

I'm going to call the local volvo wrecker see if any chance of a good shape used rear diff at a normal price.

I didn't dry the neutral shift trick, will dot that when I get the car back.

Edit: Is there an easy way (pull a fuse) to disable the rear diff and run the car as FWD for now?

[vova]

Sorry to hear about this issue. I would try to research this question a little more or ask your local volvo dealer mechanic what they can suggest(sometimes you meet normal people that can give advice for free). I doubt disabling haldex unit will help you since rear axles are still connected to the differential and will be turning it. Your issue is likely with differential bearings.
From my brief research new one is $4.2k and labor will be 2k in my humble estimate so maybe $8k CND installed. I would try to research local differential repair specialists(it is not that hard to replace the bearings with new and put new seals if you know what you doing). I would estimate bearings and seals be around 1k and labor 2.5-3K. I found this guy's offering this service, but I am sure some local guys might be able to do it as well and give you warranty. You can be lucky and find awesome used unit for 500 and pay around 2k for instalation, but with those differentials being notorious for failing(I change oil in mine every 35-40k) I would rather fix mine rather than gamble with used part. Even if they offer warranty on used part it is labor that is a killer here
https://atlanticmotorcar.com/casestu...-and-solution/

[vova]

Another alternative might be to pay for 2-3hours of labor to remove propeller shaft and both rear axles. It will convert the car into fwd. Hopefully some other guys here can give more info on it. It will likely generate a code for awd system but hopefully not enough to cause the car to fail inspection or jump into limp drive mode. You can go to the local volvo dealer and ask lead mechanic(service advisors are usually lacking precise knowledge) about such move and hopefully they will be able to answer that. Another possible place is LR2 forums they are suffering from the same and might have some answers.

[franticvike]

I've got the car at a mechanic who says they can rebuild the diff. Waiting on a call to confirm the scope of qork, but the quote was for $3k cdn to remove, rebuild and reinstall.

[vova]

I think it is reasonable. To remove and install it will likely be 3-4 hours of labor. Plus parts themselves will likely be close to 400. Plus labor on the diff itself is likely 4-5 hours. I would ask which bearings they would plan to use. Usually SKF and KOYO are great options. I would ask what seals he is planning to use(oem would be something I would insist on). I would also ask about the warranty on his work. I would also insist on replacing all the bearings inside the difference not to do this job again(?abrasive metal shavings from failing bearing causing damage to the other bearings). Also are they adjusting the differential or they send it out for someone else to set the preload, etc..)