The car is a '98 S90 with the original AW-30 transmission and 130k miles. I got the car with just over 100k miles, so I don't know what maintenance was done to the transmission, if anything. I had the problem with the sticking gearshift lever, so I bypassed the key lockout by shimming the cable shortly after I purchased the car a year ago and had no problems since.

Over the past month or so, I've noticed a "whining" noise coming from the engine bay, almost like a motor's bearing was going bad. It grew more and more pronounced but the car still drove fine and shifted properly from what I could tell. Over the past couple weeks, when I first back the car out of the garage in the morning (slight down incline out of the garage), I go to shift from R to D and it didn't engage... just acted like it was in neutral. I had to put the car back into park, then back to D and it would finally decide to take off. I've had cars with automatic transmission issues before, and it was behaving like there was a loss of transmission fluid, so the first thing I checked was the fluid level. Everything was topped up to the proper level and there was ZERO leakage under the vehicle. A light coating of oily road grime over most of the undercarriage in the engine/transmission bay area, but not even so much as a DROP of tranny fluid on my garage floor.

When the car decided to not move after sitting for a week while we were on vacation, I decided to try a transmission flush to see if that would get things going again. Just to clarify... before I drained everything, with the car in a particular gear, I could get it to move a little bit if I revved the engine. I.e. in D, if I revved up to about 3,500 RPM, the car would crawl forward a few MPH so I could maneuver it about in the driveway/garage.

I drained the pan, then put the car in gear with the engine running and the parking brake on and a flush line attached to the oil cooler connection on the radiator per the procedure described in the 700/900 maintenance FAQ. This did NOT generate much tranny fluid coming out at all. I've flushed a transmission before and the fluid comes out at a pretty good clip... this just drizzled out. I couldn't add it very fast back to the transmission because I was doing so through a rather tiny hose, but it seems like I should have been getting MUCH more out of the oil cooler connection at a MUCH faster rate. What did come out was definitely brown and "gunky" looking. Didn't smell burnt, which is good, I suppose. There are no codes, flashing warnings or indicators, or anything of the sort coming from the car.

I would VERY much welcome your thoughts. My theory is that the oil is not getting from the pan into the "guts" of the transmission... hopefully just due to a clogged filter. I have a new filter and gasket on the way that will hopefully address the issue. You will notice multiple uses of the term "hopefully." I do not relish the thought of dropping this transmission to try and find/free a stuck valve or something like that.

Thanks in advance for any help or suggestions you can provide!
Best,
-Jon

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MAJ Jonathan T. Belmont-- '98 S90 130K