Chunk found in front diff - what is it?

Need some expert advice here. I fid Fluid changes on my diffs and transfer case today in my 2015 Tacoma. Found this chunk of metal stuck to the drain magnet on the front differential. No other metal or debris came out when draining the fluid and the magnet didn’t have much debris besides this. I fished around with a magnet and didn’t find anything else in there either. I haven’t any issues or noises and I still have the OEM needle bearing on the drivers for what that’s worth. Any ideas what this is from? Im not too worried about it as I haven’t seen or heard anything out of the ordinary, but it is concerning.





Also I noticed on the ring gear what appeared to be corrosion. Kinda odd for something that sits in oil all the time. Prior to this change I put in BG 75w90 about 25k-30k miles ago (spring of 2018). Only thing I can think of is maybe water got in there, but I don’t recall going through any water any deeper than 12”-14”. This time I put Schaeffers 75w90 which I have used in other vehicles in the past and it’s always treated me very well. I know based off mileage I really didn’t need to change the fluid, but I’m kinda glad I did and hopefully I’m alleviating a bigger problem that could have been.

 

Have you changed the diff fluid previously?

 

Yes, I bought the truck in late 2016 with 21k miles all stock. Around 30k I installed a Detroit true-trac in the rear only and put in BG 75w90 front, rear and transfer case. As of today I have 56k and did 75w90 Schaeffers in all 3. I don’t beat the truck and when I have been off road I’m pretty gentle on the throttle even though it has been through some rough stuff, though probably light off-roading compared to many on this forum. I obviously don’t put a lot of miles on it as I have a motorcycle and a couple other cars I mainly drive since they get far better mileage.

I just went for a drive and hit some gravel so I could put it in 4wd. No odd noises while driving, not odd clunks when engaging or disengaging 4wd. So I don’t suspect there is any major issue. I’ve worked on cars for many years professionally and since moved onto aircraft. I don’t know what could have shed a chunk of metal that large not have signs of failure or noise. That’s what boggles me!

 

Only reason I asked about prior fluid changes was to rule out whether that’s a piece of metal that’s been hanging out on the magnet since day 1.

It’s a gnarly looking fragment, but if it drives fine then…whatever? I mean what else could you do except drain and open it up and inspect it?

 

I hear ya! I’m dumbfounded that it was in there and no other material was found either in the fluid draining or with a magnet fishing through the drain hole. I’m not about to tear it down to see what it is/was. I may as well just wait until I start to notice a noise, malfunction or failure. I hope none of those happen. But if it does, it sounds like a good excuse to regear and add a locker in hopes of 35’s. Or trade it in, though I prefer the later 2nd Gen body style over the 3rd gen.

 

It could be some flashing from the original casting ?

TOMB

 

+1

 

I certainly hope it's something that simple. It seems too shiny for something like that. My fear is that its a chunk off the face of either the ring gear or pinion, but I think I would notice noise if that was the case. I've rebuilt rear ends that had the faces of the gears galled and they had some pretty noticeable noise.

 

Is it magnetic?

 

Yes, its on the end of a magnet in the pictures. A small extendable pocket magnet, about the size of a pencil eraser.