Still tracking down acceleration vibration 2003 XC70 Topic is solved

Post by **Blacklab467** » 24 Jul 2020, 22:40

I still cannot find the cause of this vibration that occurs from a stop while accelerating to about 50 kmh (30mph). I’ve changed the lower control arms, ball joints, halfshafts, wheel bearings, inner and outer tie rod ends, struts, mounts, and strut bearings, stabilizer links, and the upper and lower torque mounts in the last year because they were all worn out. The car has 274000 kms on it.
I am installing a new haldex pump and filter when the parts arrive probably next week so I will have the driveshaft out and can check the Center bearing when I have it out.
Any ideas? Should I take it for a spin with the driveshaft out to see if the vibration is still there? Might it be the motor mounts, and if so, which one might cause this vibration. That’s about the only thing that isn’t new besides the brakes but they seem fine.
Thanks for your input.

Post by **SuperHerman** » 24 Jul 2020, 23:56

I think the propeller shaft is the most likely source, but it is hard to tell without driving the car.

The propeller shaft has three parts that can cause vibration - front CV joint which attaches to angle gear (here the grease gets hard and crusty due to age and heat from the engine and exhaust), center bearing (either the bearing goes bad or the rubber support), and the rear CV (usually not an issue). On some models the center bearing can be serviced, and the CVs can be serviced with a cleaning (search forum) or a replacement joint installed.

I think your approach is sound - remove the propeller shaft and see if the vibration goes away. While at it, assuming it does not go away, drive the car in manual mode, put it in neutral while at speed and determine if the vibration is still present, turn it to the left and right and see if the sound changes.

Report back.

Post by **jonesg** » 25 Jul 2020, 21:27

Blacklab467 wrote: ↑24 Jul 2020, 22:40 I still cannot find the cause of this vibration that occurs from a stop while accelerating to about 50 kmh (30mph). I’ve changed the lower control arms, ball joints, halfshafts, wheel bearings, inner and outer tie rod ends, struts, mounts, and strut bearings, stabilizer links, and the upper and lower torque mounts in the last year because they were all worn out. The car has 274000 kms on it.
I am installing a new haldex pump and filter when the parts arrive probably next week so I will have the driveshaft out and can check the Center bearing when I have it out.
Any ideas? Should I take it for a spin with the driveshaft out to see if the vibration is still there? Might it be the motor mounts, and if so, which one might cause this vibration. That’s about the only thing that isn’t new besides the brakes but they seem fine.
Thanks for your input.

I would also suspect motor mounts and subframe bushings, IPD sells bushing inserts that firm them up.
Check the motor mount next to the harmonic damper, they can collapse.

Post by **jonesg** » 26 Jul 2020, 13:01

have you tried tapping the gas in drive , foot on the brake.
To see if the engine is shifting.

To me , the fact it occurs under load says motor mounts are another good place to look.

Post by **- Pete -** » 26 Jul 2020, 23:55

Good advice above from superherman, as always.

Only thing I would add is if you went cheap for your CV axles they absolutely can still be ruled in as possible culprits. GKN/Lobro manufacturers the CV axles for P2 Volvo’s. Personally, I would pass on anything remanufactured or new & of less quality than GKN/Lobro.

I’m still running my original driveshaft, (both, f/r) CVJ’s & hanger bearing at 290k miles. I did replace the DEM pump in the last 10-15k though.

I have replaced both front CV axles with GKN/Lobro units, I believe around 230k miles.

Post by **gnalan** » 28 Jul 2020, 18:24

Sounds like you've changed a lot of parts. One thing I didn't see was new tires. Have you had your tires balanced lately? My front left wheel threw a weight, and it shakes like crazy. Just a thought I had, and getting your tires rebalanced shouldn't cost too much.

Post by **Blacklab467** » 28 Jul 2020, 23:42

Yeah new tires last year, the vibration is on acceleration from zero to about 60 kmh, goes away when coasting and decelerating. I’m going to look at the mounts tomorrow, also remove the prop shaft because I have to replace the Haldex pump next week. I’ll take it for a spin without the shaft and see if it still vibrates and report back.

Post by **br0dy519** » 30 Jul 2020, 20:11

I just tracked down a similar vibration the other day. It ended up being the heat shield on top of the exhaust manifold. Might not be yours but worth a try.

Post by **Blacklab467** » 31 Jul 2020, 07:24

I think I might have found the problem yesterday. The right lower motor mount looks pretty bad and oil soaked. I have changed the upper mounts and transmission torque mount about a year ago. I will now order the two hydraulic mounts and the right lower and report back.

Post by **Blacklab467** » 18 Aug 2020, 08:15

Still having issues finding the vibration. I've removed the propshaft because I'm repairing my AWD so it is out of the car.
I've replaced the CV Shafts with Cardone units, had a similar vibration so received and installed a second set, still the vibration persists. Now I don't know if its the cheap CV's after trying two sets or if something else might be causing it? I've replaced essentially everything on the front end and all the mounts. I'm at a bit of a loss on what is causing the vibration now. I also took the bevel gear out to service it and change the fluid and it appears to be serviceable. Wondering if something inside the transmission could be vibrating but I don't really think so.
Any ideas? Thanks.