Pulled auto transmission pan, 100s-1000s of little steel beads

02 outback with 160k miles. Pulled transmission pan to do filters. Removed magnet to clean it and found 100s to a couple thousand tiny beads about 1/64 or .3mm. The are all very uniform and magnetic, so I’m guessing steel.

Transmission doesn’t seem to have any issues, maybe just a very slight hesitation when shifting, but not enough to worry about.

Anyone ever see anything like this in a transmission?

*Please don’t respond with “looks like you need a new transmission”. I know lots of people on here own and work on Subarus, I’m wondering if anyone here has seen this EXACT issue before.

Update: got the correct answer here, for anyone who is interested: https://www.reddit.com/r/whatisthisthing/comments/ubz8z4/pulled_the_pan_on_my_transmission_to_clean_the/?utm_source=share&utm_medium=ios_app&utm_name=iossmf

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I am reminded of the “dead parrot” sketch from Monte Python. You have a former transmission. Those little balls likely used to be part of an overrunning clutch. Put a remanufactured transmission in the car.

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I wouldn’t be so sure about that last part.

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Nah, I would say on a scale of 1-10 with 10 being the best, the transmission is functioning at a solid 7or 8. I’m really looking for someone who has seen this exact problem before.

Something is coming apart inside your tranny. Could last a day or a year, but ground up pieces of metal or tiny bearings (which I can’t find on diagrams) should never show up on the drain plug/magnet.

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I was under the impression that any bearings in this transmission where needle or roller. After reviewing the diagrams, I cannot imagine where these came from. They are ball-like, however, not perfect spheres.

You’re speaking with someone who has personally built more automatic transmissions than you will ever see in your lifetime, but have it your way.

Sorry, didn’t mean to come off dismissive. I’m not disputing that it could be from the overrun clutch, I’m just saying that I’ve been driving this car for years and the transmission does not appear to be failing or in its death throes. It’s driving pretty much the same as it has for the last 10 years.

Over those 20 years/160k miles, how many times have you changed the trans fluid?
If it was less than 5 times, then I submit that you participated in the demise of this transmission.

Might they be part of friction material, embedded in the asbestos (or whatever)?

Have changed fluid and (external) filter approx every 30k. This is the 5th change.

That might be casting material that was attached to the casting and is now releasing.


HEY! Now we are getting somewhere. Wow, good call. I’m going to look into this. Thank you!

I haven’t. Curious what the outcome is.

As far as the casting material theory…how much cast iron is even in a Subaru transmission? Most automatics have a cast aluminum case with mostly steel internals. If it’s 100’s of little beads, I kind of doubt it’s sloughed off casting material.

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Especially if this stuff is magnetic.


I got a confirmation from a guy who does this for a living, that they are in fact Steel shot peen left over from the manufacturing by process. Apparently they blast the interior and must have been sloppy about cleaning it up. He said that they likely have never interacted with the transmission at all and since the pan had never been dropped (it was leaking that’s why I removed it) they have just been clinging to the magnet for 20 years. Pretty relieved.

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I’m sorry, but I’m very skeptical that it’s “steel shot peen left over from the manufacturing” and everything is fine

I’ve had plenty of transmission pans off and I’ve done plenty of repairs

Any metal at the bottom of the pan is not a good sign, imo

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I had a summer job at an iron foundry while in college. My station was “knockout” just before the “shot tower.” I swung a sledge hammer and knocked off the extraneous metal pieces (“gates and risers”) left over from the sand casting process. The moving assembly line then took the castings up to the shot tower, where they were bombarded with small metal balls like those shown here. Sometimes a large casting would jam in the shot tower and the assembly line would slow, strain, and then jerk to a stop. It was a high priority for me and my coworker to climb up there, shut off the spray of shot, dislodge the stuck casting, and turn the assembly line back on.

The castings that had been stuck up there were exceptionally shiny and smooth. If there was shot lodged somewhere in the castings, cleaning that out was someone else’s job, someone I never saw, further down the line.

Someone should have cleaned out the shot from those transmission castings - but maybe the design of the tranny makes them an interesting artifact, and not a functional problem.

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Thanks for the reply. I bet it’s just a quality control thing. Subarus IMO is shit for quality control. There are so many broken and mangled doodads in this vehicle. Two door handles ripped off, dashboard foam delaminating, door panel broken, mirror motors don’t work, windows motors suck. I own it purely for the all wheel drive.

Well, thanks for the follow up. Pretty amazing some of them didn’t wind up somewhere bad inside the transmission before they found their way to the magnet. Assuming all of them have found their way to the magnet…. Just something else to worry about. Have a good night! :stuck_out_tongue_closed_eyes:

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