2006 XC70 Vibration when Accelerating

65stang · Post by **65stang** » 11 May 2014, 06:03

I have a 2006 XC70 AWD with 130,000 miles. I took a long trip (~800 miles each way) and noticed a vibration that progressively got worse throughout the trip. Whenever I accelerated (even slightly) at highway speeds (~70 mph) there was a vibration that was easily felt through the steering wheel. Here's what I've done:

- new tires
- new inner/outer tie rods on both sides
- new CV axles on both sides
- alignment
- new coils
- new spark plugs

The vibration is definitely better and I can no longer feel it through the steering wheel. But its still obvious.

I got under the car and looked at the prop shaft (rear cv axle). The carrier bearing looks good and I couldn't feel any play in the prop shaft.

What on earth is causing the vibration? It happens between 2000 - 2600 rpm when I'm accelerating at any speed.

Is it the Engine or something in the rest of the drive-train? Timing belt stretch? I'm at a loss.

Thanks,
Scott

Post by **abscate** » 11 May 2014, 06:18

Could be in the exhaust system, specifically the cat? I've had cars where loose pieces of catalyst made funny noises in this rpm range.

Post by **vtl** » 11 May 2014, 06:59

Check front LCA bushings.

Post by **oragex** » 11 May 2014, 08:55

The CV axles, where Volvo parts or aftermarket? Aftermarket/rebuilds are prone to vibrate because usually wear did extend to areas that cannot be replaced when rebuilding.

Did you notice the vibration prior during similar drives on highway or it started happen all of a sudden?

Other than the CV joints, what is typically causes vibration at highway acceleration on these vehicles, it's the lower control arm (LCA) bushings (the larger one of two bushings). It's typical.

65stang · Post by **65stang** » 24 May 2014, 08:09

I just looked at the upper engine mount / stabilizer (the bar that goes over the engine and connects to the shock towers). The whole bar easily pivots forward and back by hand. Also the connecting arm that goes to the top of the engine from this bar has a lot of play. The rubber inside the top engine mount has plenty of room to move, as well. I'm assuming this is not normal? Could this be the vibration under load?

65stang · Post by **65stang** » 24 May 2014, 12:38

The front lower motor mount on the passenger side looks ok, I think (first two pictures). What do you guys think?

I'm pretty sure the upper stabilizer bar mounts (mounting points at either end) and the engine mount (connecting bar to the engine) has way too much play and they all need replaced.

Here is the front engine mount behind the passenger front tire:

Same one from the front side:

Here is the top motor mount:

And a video of the movement of the top motor mount:
http://youtu.be/vPaKZ9slJac

Post by **jimmy57** » 24 May 2014, 14:19

The mounts could be the cause or the result. If you have any vibration after mounts are done then inspect the front CV joint on rear driveshaft.

bugeye · Post by **bugeye** » 25 May 2014, 07:20

By the look of the marks on the aluminum just left of the nut, the rubber in the top mount is worn. In a new top mount, the rubber is tight against the aluminum. Replacement of the complete mount is easy. Also check the lower mount at the transmission.

Post by **abscate** » 26 May 2014, 08:11

5mm of play plus (from video)

Both the engine mount and cross bar mounts need replacing IMHO

65stang · Post by **65stang** » 30 May 2014, 08:06

I changed out the upper motor mount and the two upper stabilizer end links. It's improved, but the vibration when accelerating is still there.