First off, new to the XC forum, but looks like a lot of great stuff, and hopefully someone can help me out....volvo's engineers are stumped
My wife has a 2008 XC70 that we bought brand new. At 10,000 miles the vehicle started having a vibration throughout the whole car (appeared less front end, more rear end problem). We attempted to chase it with the selling dealer (only one in local area) and never got anywhere. The issue was blamed on our tires, and I wasnt putting new tires on the vehicle when it was still brand new. Dealer wasnt helpful and I gave up - would add the vibration concern to the issue list at every oil change, but nothing was done about it. Now fastforward - the vehicle has 65,000 miles, new tires, and the vibration still exists (its bad enough I will not drive the car long distances as I cant stand it - and the car was bought as our family roadtrip vehicle). The selling dealer was acquired by another line of dealerships which is known for extrodinary service. So, at the next oil change I asked for the issue to be looked at. Immediately, the service advisor agreed there was a problem, and the issue came to who would be responsbile for the diagnostic charges - the extended warranty unfortunately isnt a Volvo warranty and thus doest cover diag. Upon looking at the service records, apparently the only good thing the old dealer did was document that the vehicle had a valid vibration concern starting at 10k...so thankfully Volvo has stepped up on the diag costs. Thats the background....(sorry for the long post)
The vehicle has been in the shop going on 5 weeks now, and they have 60+ hours into diag and we arent making progress. The regional volvo engineer has been leading the diag personally, and has spent 3 days in the shop with the vehicle and driven it many times....
The issue:
Whole car vibrates/shakes at 50+ mph
Whats been done (all Remove/Replace items come off another vehcile that was proven to not have issue):
1. Rule out wheel/tire issue - vehicle has brand new wheels/tires on it that were proven good on another vehicle for all further diag concerns
2. Check all fluids in drivetrain
3. Shut off engine at speed
3. Check body/engine mounts - found both rear body mounts cracked in half. Replaced. Issue not resolved
4. Remove Driveshaft
5. Remove/replace front axles
6. Untorque/Retorque all suspension components
7. Remove/Replace Rear AOC (explained as secondary transfer case in rear of vehicle)
8. Remove Rear Axles - Drive car in 2wd only, nothing spinning from TCase back
**Issue was thought to be resolved after first testdrive with no rear axles, meaning either a rear axle or rear diff issue. I was asked to come drive/confirm with nothing in the rear end spinning, and halfway thru the testdrive with the service manager the vibration came back and didnt go away.
They have put 100s of miles on the car test driving with various parts combinations, and the following additional observations have been made:
1. When the car is driven immediately after coming off the lift, before the suspension completely compresses, the vibration is gone
2. A slight grinding noise is developing in the vacinity of the gas pedel in certain infrequent situations.
3. Any brakes/bearing issues have been ruled out since the vibration hasnt changed and nothing has broken in 50k miles.
One of the tech's apparently is leaning toward the tranny, but the shifts are all smooth and there is no apparent issue there. Im a 4wd truck type guy, not an AWD guy, so all these extra components to introduce slip are new to me. After digging thru the info on this forum, it sounds like we should be investigating the Bevel Gear (especially on account of the slight grinding noise now developing).
Can someone post a diagram of the entire AWD system layout in the car? The way I understand the layout, power from the engine is transfered to the transmission, then the bevel gear, then the tcase, then to the front diff and the rear driveshaft which couples to the AOC then the rear diff. The service manager hasnt mentioned the bevel gear and struggles to explain the power transfer in terms of components from the engine to the road....
Can anyone shed some light on this issue? Volvo and the dealer have been great, but we are all frustrated and looking for a solution. And yes, buying back the car has been brought up, but I own it outright and hate to take on a new payment as they arent handing me the keys to a new car....
Thanks for reading this long post.
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