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Old 09-15-2019, 04:40 PM   #1
Scooby Newbie
Member#: 506367
Join Date: Sep 2019
Location: Atlanta Ga
2001 OB-LL Bean

Default AT OIL TEMP LIGHT Flashing 2001 OB (Bean)

My daughter purchased used Bean OB (2001 Outback/L.L. Bean; 3.0 Engine, 4EAT transmission) in April, 2019 with ~147K miles. AT Oil Temp light issues (see below) started @ ~154,500. I’m am fairly experienced with working on cars, but this is my first Subaru. Experience with transmissions is limited to basic maintenance/service.

Overall the OB looks to be in pretty good shape – engine runs great, ride is solid, etc. I’m now debating whether to try and fix the OB or just cut my losses. I have extensively researched the ”AT Oil Temp light flashing” issue online, and would GREATLY appreciate any advice offered on what my best options are…fix the OB or get rid of it and cut my losses?

And for all you fathers with daughters out there, this is a classic “rescue daddy” situation. I would much prefer to fix the OB if possible as this is my daughter’s first experience buying a car on her own. I’d like for it to not be seen as a tragedy by her (just maybe with a lesson learned that asking dear ol’ Dad for help early is a good thing).

Current Symptoms
  • AT Oil Temp light flashing Code 79 (Transfer duty solenoid) with OB going into AWD mode (torque bind, etc.) as soon as AT Oil Temp light starts flashing.
  • AT Oil Temp light flashes and goes into AWD mode whether in normal or 2WD drive mode (fuse inserted)
  • BUT…the OB will go much longer/farther in 2wd mode (fuse in) before symptoms arise than in normal mode (fuse out)
  • Definitely temperature related more than miles driven - AT Oil Temp light never flashes in cool weather or when driving through rain.
  • And AT Oil Temp light stops flashing once car is cooled down, only to arise again after being driven in hot weather, stop & go, etc..
  • Also…Check engine light recently came on with code indicating misfire on cylinders 2 & 4. I believe this in unrelated but wanted to mention just in case. Probably just needs new plugs?

Maintenance performed (so far)
  • Completed 3 drain/refills on trans fluid, with new trans filter installed on 3rd drain/refill. This seemed to offer some improvement in that OB now goes further/longer before AT Oil Temp light flashes and AWD mode kicks in.
  • 1st drain refill indicated that trans fluid had likely never been changed/serviced. VERY dark brown (nasty stuff).
  • Also completed 2 drain/refills on rear differential and 1 drain/refill on front differential. No noticeable improvement noted. Condition of drained differential fluid reasonable, with no noticeable contaminants or metal shavings present (I’ve seen much worse).

I went to a highly recommended local independent Subaru shop and was told that if AT Oil Temp light flashes and AWD symptoms arise in 2WD, problems are deep within transmission and the only fix is to replace transmission at minimum of ~$2,500. I was about ready to write the OB off at that point, but after looking into issue a bit further online, I question whether this is truly my only remaining option. Based on what I have been able to find, it looks like a DIY project to replace the transfer duty solenoid & clutch plates will very likely resolve the issue and get the OB back on the road again.

Is there anything else I missed that I should consider as possible solution/fix?

If not, is it worth the effort to try replacing the transfer duty solenoid myself (along with clutch plates)? I’ve looked online, and I believe this is something well within my capability. But it is a helluva project, and I don’t want to do it unless there is at least a reasonable chance of success. The best link I found for transfer duty solenoid replacement is at https://forums.nasioc.com/forums/sho....php?t=2501432. Any advice, suggestions, references, links, etc. are much appreciated.

Finally, before considering replacing the transfer duty solenoid myself, I thought I’d do one more drain/refill of trans fluid and add BG ATC additive to see if this helps. Sound reasonable?

The over-riding question to all you Subaru enthisiasts out there is, “What would you do if you were me?”

Thank you so much in advance for any assistance offered. This is my frst post on your forum...hope it is OK.
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