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Subaru Forester Transmission Questions

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  • 1998 Subaru Forester, 160,000 miles. I may have a similar problem: 160,000 miles, Forester AWD, automatic. Wisconsin/Minnesota sub-zero, snow, icy roads. Driving this AM it started jerking to right and left...but controlable...no noise, just pulling in short jerks either direction...pulled to side of road, stering wheel slight wobble on a off...checked lugs...new axles and boots but slight rip in the boots suggested snow and crap may be in there...none...later, after creeping home 20 miles with flashers it subsided. Seems OK on clean roads...but suspect viscuous differential...drive shaft can be turned by hand while on lift and rear wheels will rotate...What Goes???
  • paisanpaisan Posts: 21,181
    Ice/snow buildup on a rim?
    Loose strut top mount?
    tie-rod end?
    Bearing?
    Ball joint?

    -mike
  • paisanpaisan Posts: 21,181
    If you have a cracked boot on your CV, the grease is or will come out and dirt get in and your CV will be shot in short order. Make sure to get it replaced ASAP.

    -mike
  • ateixeiraateixeira Posts: 72,587
    We had that on our 626. The boot tore, grease leaked. Fix is ASAP, because ours leaked grease that shorted out the O2 sensor. That increased the cost of the repair.

    Also agree about the possibility of ice on the rim. If you can, clean it and wax the rims. If not at least scrape off the ice, and maybe spray a tiny bit of WD40 in the area (not on the tire, though).

    -juice
  • Thanks for input. All joints etc check out OK except boot cracked and needs replacement.

    However, why won't the rear wheels engage in All Wheel Drive, only fronts??
  • morsethmorseth Posts: 10
    Hello everyone,

    I just bought a new '07 Subaru Forester, automatic trans, 5 days ago. It's my first Subaru, so I was pretty excited about that.

    Unfortunately, I've noticed a strange sound while driving. The sound seems to be coming from under the car (wheels, drive train, etc), but I can't tell if it's from the front/rear or left/right. It's hard to explain, but the sound is kind of like a tapping/hammering noise. Almost like the sound of a very loud valve tap.

    It can only be heard at speeds between about 35Mph and 60Mph while accelerating and the RPM is held between 2300 and 3500. If I roll down the window at those speeds to try and pinpoint the noise, the wind washes out the sound.

    This noise is much more pronounced when accelerating up a hill in this RPM range. Letting off the accelerator makes the noise stop, and mashing the pedal to force a downshift makes the noise go away (higher RPMs make it hard to hear or completely gone). As the RPMs increase, the speed of the tapping increases too. While the noise is occuring, if I put the transmission in Neutral and rev the engine to those RPMs, I cannot hear the noise.

    I also noticed yesterday that when this tapping noise is occuring, steering the car affects it. If I steer/swerve quickly to the left, the tapping noise gets much faster and a little bit louder. If I swerve to the right, the tapping noise briefly disappears until I straighten out again. Making a very hard left turn (like at a stop sign) seems to increase the chances of the noise occuring when I hit that 35-60Mph speed range, while making sharp right turns sometimes eliminates the problem for just a little while.

    I'm afraid this could be one of those deals where the dealer service techs either won't hear it since it's intermittent, or will say it's "normal". If I can take it in for service with at least some idea of what the problem might be, that might be helpful. Anyone have any ideas? Wheel bearings, steering rack, differential?

    Thanks,
    Bryan
  • ateixeiraateixeira Posts: 72,587
    From the first half of your post I was thinking loose heat shield. It might only rattle at certain frequencies.

    For the 2nd half, I was thinking wheel bearing.

    Maybe at the first oil change have them inspect those areas. You can register a "customer says" call with 800-SUBARU3 so that if it ever gets worse you can prove you noticed it while it was still under the full warranty.
  • morsethmorseth Posts: 10
    Thanks for the quick feedback!

    I've owned cars with noisy/rattling heat shields before, and this doesn't sound too similar. I'm not ruling it out, but it doesn't seem like that would be it. It's really not a metallic rattling type sound. It's more of a tap or a knock, like a "piston slap" type noise. It only does it at certain speeds. Driving slowly at 15 Mph between 2300PRM and 3500RPM does not cause the noise.

    The sound is very rhythmic and repeatitive once it kicks in, not at all random in nature, like a baseball card in a bicycle tire. The faster the RPMs are, the faster the tap/knock is. Once it gets to about 3500 RPM, the taps get so fast and close together that I can't hear or perceive them anymore.

    It seems as if the noise is louder as the load on the engine increases. Going up a steep hill, the noise is very pronounced. On a flat stretch of road I can hear it, but the noise is much quieter.

    I think issue of swerving left and right making the sound worse and better is important to the diagnosis, I just haven't figured out the correlation yet.

    Bryan
  • paisanpaisan Posts: 21,181
    Could be a bad CV joint/axle assembly.

    -mike
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,276
    I am definitely leaning toward a wheel bearing, but yes, it could also be as Mike suggested. Increased torque on either of these is going to cause that rhythmic tapping noise if it is only beginning to go bad. The CV tends to be symptomatic only during turns early on, but that does not mean it always has to be this way.
  • kdshapirokdshapiro Posts: 5,751
    I'm wondering if it's the piston slap problem. My car exhibits this when the temperature goes below 40 degrees. It's a tap, tap, tapping. Above 2K the car noise drowns it out. Below 1500 you can't hear it. In warmer weather it disappears.
  • paisanpaisan Posts: 21,181
    I'm saying CV due to the "clicking" he mentions. A bearing is more a whirrling than a clicking.

    -mike
  • morsethmorseth Posts: 10
    Ken:

    At first, I also thought maybe it was piston slap. But it doesn't make sense to me that the vehicle needs to be in motion to hear it. I would think if it was piston slap, that I would hear it while standing still and reving the engine while cold. It only happens between a very specific speed range and RPM. The engine idles smooth and quiet, even after a cold start first thing in the morning (I'm in PA, and it's still cold here right now).

    I could be wrong, but my gut feeling is that it's not the piston slap problem.

    -Bryan
  • morsethmorseth Posts: 10
    Michael:

    If it were a CV joint problem or bearing problem, does it make sense that shifting into Neutral makes the noise go away? Is this because I am just coasting and no longer delivering torque to the wheels?

    Is it common to have a faulty CV joint or bad wheel bearing right off the showroom floor? The car has less than 200 miles on it!

    Bryan
  • xwesxxwesx Fairbanks, AlaskaPosts: 8,276
    No, your conclusion is correct on this one - if it does not happen while the vehicle is not in motion, then it is further down the system - it is not the engine.

    I agree that a wheel bearing tends to be a "whirring" noise to start. Seems strange to me though that you would hear a CV while driving straight ahead. The sound happening while turning one direction only, though, that is a classic symptom... until it gets very bad, anyway!

    Very rare to have a problem like that "fresh off the showroom floor," but there are ALWAYS some defective parts to leave every assembly line. Always.
  • kdshapirokdshapiro Posts: 5,751
    Bryan - I don't hear the piston slap until the engine hits a little before 2K. Meaning the noise is not there at idle or start up. Search the Subaru boards for piston slap for more information. Piston slap is *not* heard at idle.

    Piston slap is a distinct tick-tick-ticking, which sounds like it comes from the passenger rear part of the engine compartment underneath.

    Ken
  • paisanpaisan Posts: 21,181
    Could it be something like un-removed packing material from around the struts? I know when the STi first started shipping 99% of the dealers didn't un-pack some of the packing material and it caused issues.

    -mike
  • morsethmorseth Posts: 10
    Ken:

    Thanks very much for the info. It could very well be piston slap that I am hearing. The car is still very new to me, so I'll need a few more hours behind the wheel to help me understand what I am hearing.

    I've gotten some great information from all of you here. I'm going to look at and try some things over the next couple of weeks. I'll report back and let all of you know what I find out.

    Thanks again for everyone that contributed ideas. It's very much appreciated!

    -Bryan
  • kdshapirokdshapiro Posts: 5,751
    Good luck and keep us posted.
  • ksychksych Posts: 1
    Hi Bryan, I am so glad I cam across your article. I am having the exact same problem you are having and just about to take my car in for first oil change. I too have a 2007 Subaru XT. I much appreciate any information you can provide regarding your experience with the dealer (that is of course assuming you have taken your car in). Did they ever find the cause of the annoying noise?
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