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2011 Forester Auto :(
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Discussion Starter · #1 · (Edited)
'11 forester N/A - Axle or wheel bearing? - SOLVED

Hello,

I am hoping to get some feedback to help diagnose a driveline issue i believe I have. I recently acquired a 2011 Forester FB25 with the 4-speed 4EAT automatic that was suspected of having a blown motor but ended up only having a bad radiator instead. It has 236k miles, and as far as I am aware, both the engine and transmission are still original to the car and have never been replaced/rebuilt. I have done some preventative maintenance (never trust the PO), which has included the usual oil change and replacing both the front and rear diff gear oil. Rear diff seemed ok-ish and the gear oil that came out looked like gear oil. The front seemed a bit watery though, and the o-ring on the front diff dipstick is in need of replacing as it doesn't seal well. Replacement gear oil was Royal Purple 75w-90 with LSD additive as specc'd.

Now on to the issue I hope to fix. When I am traveling at moderate to highway speeds and apply more than cruise throttle, I get a pretty good bearing-like growl. I tried to capture the sound on video but have not been successful yet. The specific constraints I have been able to narrow down are:
1) speed faster than 40mph
2) faint growl maintaining speed
3) pronounced growl when adding up to 25% throttle (more kicks trans down out of 3rd or 4th)
4) growl also manifests as vibrations felt in the dead pedal and steering wheel and subside when throttle angle is removed
5) growl is NOT engine speed dependent
6) appears to only be present in gears 3 & 4 (may only be correlative as engine noise may drown out growl in 2nd due to high RPMs)

Unfortunately, in my searching online, most references are to higher pitched whining of gears/bearings than a deeper growl/vibration. Currently I am leaning towards (hopefully) a center carrier bearing, or possibly one of the 4 bearings in the center diff housing. Less happy options so far are the front diff bearings or that the trans has an internal bearing issue with the 3-4 planetary stack and will require a replacement/rebuild.

Additionally, i have not seen many resources for rebuilding the 4EAT. There are a few manuals out there but they seem to be for the late 90's and not 2011. I think from 99 on, the 4EAT was basically the same Phase-II build in most subarus? if so, this may make finding a core trans to rebuild easier.
 

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2011 Forester Auto :(
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8 Posts
Discussion Starter · #2 ·
After a bit more searching and troubleshooting, I'm beginning to think this may be an axle or wheel bearing issue rather than Trans/Diff.

I did inspect the front driveline and I could not find any indication of bad wheel bearings, ball joints or tie rod ends (although my rear A-arm bushings are in need of replacement). The center driveshaft bearing also seemed to be OK at first glance. The right side CV axle (appears to be original) did seem to have a lot of ind play compared to the (newer, replaced at some point) CV axle. I added some grease to both the inner and outer CVs on the passenger CV via grease needle. Subjectively it MAY have quieted down a little, but not so noticeable as to be able to claim the CV is the issue. On the list is to put the car on 4 jack stands, check the rear and spin up the driveline in the air to see what is growling.
 

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2005 Forester Automatic
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Can you swerve a little to left and right while driving at the speeds you describe? See if the growling or vibration changes. if it does, that too would lend support to the CV joint theory (which was what I was thinking as I read your first post). Or one of your front wheel bearings.....
 

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2011 Forester Auto :(
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8 Posts
Discussion Starter · #4 ·
I did try slaloming the car a bit at speeds, but this did not appreciably change the noise. While it was a couple days between driving before and after greasing the axle, so its a bit hard to say positively that it helped. From what I recall, it does sound less bad now, especially since it mainly shows up under load. I'm thinking I may replace the seemingly original (at 236K) right front axle and see if that helps. If anything, it may save me a stranding due to a dead axle later...
 
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