02 Outback acceleration vibration

[2.5Turbo]

First post here...been digging around a lot lately and this seems to be a good place! Anyway, I've had my 02 Outback for a few years now, but haven't done much work myself since it's my car at school and all my tools are on the opposite coast ;). My wrenching background is with mainly diesel Mercedes-Benzes; my car at home is a 1990 300D 2.5 Turbo (hence the user ID). So I'm relatively new at working on AWD vehicles.

Anyways, on to my issue...

I've been trying to figure out what's been causing a slight vibration on acceleration in my 2.5L auto-trans Outback. The vibration seems to manifest itself when accelerating up a hill between about 25 and 30mph, and again around 55-60mph. It seems to be speed related, not engine RPM related. It doesn't seem to matter if I'm giving it a lot of gas or a little, it still vibrates. I seem to notice it mostly in my feet and a little in the wheel. Reading around on here has lead me to either a bad CV axle or a failing U-joint. I recently drove it with the FWD fuse in and it was the same, if that helps. I'm also not getting any squeaks or clicks normally associated with bad CV's.

I'm also trying to track down a chirping noise also on acceleration. Originally I thought it was a belt, but I had them changed at the last service and it still does it. I checked the tension on the alternator belt and it seemed a little loose, so I tightened it a bit, but it still chirps. It doesn't do it when revving the engine in neutral, only when the engine is under load. Is the new belt squeaking because it got toasted by the low tension, or could it be something else?

[green97gt]

as for the vibration, i would have your tires balanced/ceck them for cupping, especially if you can feel it in the wheel, and it it only at certain speeds.

the chirp is an interesting one....by chrip do you mean, once or kind of whistle on accel?


if it chirps only once on accel.
since the belts only drive accessories, you could remove them and drvie it around the block(keep in mind you wont have PS and the ALT wont charge, but thats a no brainer.) see if it still chirps. if the chirp is still there, its not the belts.

my POS van "chirps" on accel, from leaving a stoplight etc, its a worn bushing under there somewhere and the tranfer of load causes it to shift and grind/chirp, thats kinda why i ask only once, or?

if its a whistle/warble sound on accel, every subaru ive owned has made that noise when they get higher mileage, ive found its mostly exhaust leak, like mine was at the EGR, it would whistle.

these are all just some ideas, good luck.

[2.5Turbo]

The chirp isn't only on takeoff, in fact it doesn't really do it unless I've been accelerating for a bit, like going up a hill or merging onto the freeway. The chirps are very quick, and keep happening frequently and randomly as long as I'm accelerating fairly briskly. I'll try running without the belt this weekend...on my Mercedes the water pump is driven by the serpentine belt so driving around without the belt wasn't the first thing that came to my mind :lol: ...

Re the tires...would bad balance and/or cupping cause vibrations all the time, not just during acceleration?

[green97gt]

a tire that is out of balance or otherwise hosed can cause all sorts of crazyness... sometimes all the time, sometimes only as 57 miles an hour going down hill with a dog in the back, and a slight crosswind. :lol:

my dad swore he had rear diff noise, rotate tires, everything, turns out they were the goodyr assurance tires, just plain noisy on the back, but not on the front, and they cupped funny too.

if you take off your wheels and bring them in, a shop shouldnt charge you more than ten bucks to balance them.

or try rotating your tires, see if you feel it more in your butt than in your wheel/feet, if so thats your issue.

or you could sell it to me for real....real... cheap :lol:

[ouch1011]

My car had the same vibration issue in 2nd gear when it had the 4eat still in it. Moderate acceleration in 2nd around those speeds would result in a vibration. I never really tracked it down, but when I swapped to the 5mt it went away. But vibration under acceleration is typically caused by either driveline angles being off, u-joints or cv joints binding/sticking, or worn engine mounts. A worn carrier bearing bushing can cause this problem too since it throws the driveline angle off, but I kind of doubt that is your problem since driving in FWD didn't change anything.

[2.5Turbo]

So I drove it around with the belts off today and the chirp was the same, so that's ruled out. I'll try to make a video or something this weekend so you all can hear it. It's pretty subtle; kind of hard to hear it unless you're next to a barrier or something. I did try loading the engine with the transmission in gear and I'm pretty sure I didn't hear it, so the engine doesn't seem to be making it. Wonder if the two are related.... :-?

And by the way, the vibration doesn't seem to be gear-dependent. I've felt it in second, third, and I'm pretty sure in fourth.

[2.5Turbo]

Video is up for the chirp. The video is all uphill driving except for the first five seconds or so. The chirp isn't all that obvious, but it's there. It's easier to hear next to guardrails and such.

http://www.youtube.com/watch?v=8ZiKdLlN2h0