metal in diff housing, problem?

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Nov 10, 2003
hey all,

Had my 97 lx 450 in for 60k service today and when the front diff drain plug was pulled it had some metal shavings on the magnet. The shavings were about 4mm - 6mm wide and very thin,around .002 , there were about 2 or 3 plus some smaller shavings. The diff oil was most likely the original (71k miles) very green but no signs of grease that I could tell , it was pretty fluid but thicker than new oil.
The front tire tread is also thicker than the rear tire tread and I was wondering if this also had an effect on the premature wear as well as the old diff oil. The tire tread readings were: front left 11, front right 11, rear right 5, rear left 5 Michellin ltx.
Any thoughts on these shavings? My front locker seems to engage fine. Do you think someone drove improperly with the front locker engaged?(I am the 4th owner) Should I be worried?

Thanks for the advice
Mark :cheers:
"some" metal is okay...that doesn't sound too horrible given the low amounts, but it is an indication of wear happening...

Do you have any noises while driving? If that was indeed the very first change it is possible to have some metal from way back and the gears were meshing...

I defer to the masses.
No noises while driving, Thanks for reply
I will say this...I would perhaps change the diff fluid out in a shorter interval and check the plug again.

If you see even more metal....that would make me more suspicious.

I would also keep an ear out for a howl or any other gear/metal grinding sound to be sure.

SO hard to guage the severity based on words...Everyone needs a digital camera =)
Definitely change the fluid again soon.

It's likely just normal wear and tear, but one important thing you didn't mention was whether there was recently any work done on your diff, like regearing or locker set up etc.

:flipoff2: :D
No regearing on diffs by me. Doubtful the previous owner regeared cause it drives similar to other stock 80's I tested. I am just wondering if the different tire size has anything to do with premature wear?

Does not sound unusual to me, especialy if that is the original fill. It went way too long though. I suggest a 15k mile interval if you do not go swimming. Otherwise it should be done soon after going for a swim.

[quote author=9780 link=board=2;threadid=7806;start=msg65564#msg65564 date=1069337185]

... it had some metal shavings on the magnet. The shavings were about 4mm - 6mm wide and very thin,around .002 , there were about 2 or 3 plus some smaller shavings. The diff oil was most likely the original (71k miles) very green but no signs of grease that I could tell , it was pretty fluid but thicker than new oil...


The metal you are seeing is not the result of wear. It is swarf left over from machining the axle. It's shameful that the factory did not clean it out properly prior to assembly. No need to worry, as there is nothing to be done now, short of disassembly of axle and cleaning it out, which would not be economical (or reasonable) in the absence of other problems.

The green, thicker gear oil is a sign of grease. Compare the drained front gear oil to the back. Absent of grease, they would both look pretty much the same.
rear diff had similar color but not as thick , like it was probably done at 30 k?
thanks mark
perform this opperation on a daily basis , ALL the ones i do at the dealer look the same as yours, as stated above its normal left over material from production, I have also not seen any failures as a result of it !!!! peace of mind good!!!!!!!
thanks all, :cheers:

I have a little more piece of mind now, Thanks
Those are machining pieces and both my diffs had a few - the rear had about twice as much. I put mine in a baggie and showed them to the Chief Engineer of the LandCruiser program who happened to be in town from Japan. He pronounced them normal. The larger pieces looked like a baby's fingernails in shape and thickness.

So, if these match yours, they are definitely NOT normal wear. Wear would be fine filings. And this is not an error on Toyota's part but quite common in as complex an assembly as a diff. It is the reason for the magnetic drain plug Toyota put in. Other makes without magnetic plugs simply eat their machining shavings.

I appreciate that the junk showing up is common, and therefore Toyota is free to accurately state that finding the stuff is normal. I wouldn't say that it is appropriate. There is no reason that the axle manufacturer can not clean out the axle tubes prior to assembly. How much would that would add to the cost? Not much. I don't think it does the diff any good to be circulating that stuff through the gears. I've pulled out pieces that perfectly matched the gear teeth profile, having obviously been passed between the meshed teeth of the gears. I'm not loosing any sleep over it, but that kind of sloppy manufacturing does not meet my expectations.


Suit yourself as to what constitutes 'sloppy manufacturing', but I think it's worth noting that if there's one thing Toyota knows how to do it's precision manufacturing. The question is not always "what would it cost to clean" but "what's the downside of not chasing every tiny little piece?" I'd guess that someone at Toyota's axle assembly operations knows exactly what those pieces come from, their rockwell hardness, and that they can pass through the gears till the cows come home without damaging anything.

Where the metal chips come from is not a secret. They come from machining the axle housing. Such contamination can be bad news for the bearings. Usually the bits get caught by the magnet before doing serious damage. Not always.

Cleaning out the swarf after machining is easy and reasonable to expect. I've got the same stuff, which I made myself, sitting on my workbench in the garage. When I leave it on the bench, without cleaning it up, I am being sloppy. When I leave it on the garage floor, I am being sloppy. Were I to leave it in a finished product, I would be ever more so sloppy. I hold myself to the same standard.

Quite some time ago when servicing my RX7 I removed the same kind of manufacturing debris from the diff. Along with a chunk of a broken gear tooth. All nicely stuck to the magnet :(. Perhaps that helps explain my perspective.


I agree less debris is better - can't argue with that mindset. But Toyota is not ignorant of the finished condition of their pieces and they made the decision that a few pieces of soft iron are not a big deal in the presence of hardened gears IF they can even circulate once before ending up on the magnet (doubt it). The broken tooth on your RX was almost certainly not due to manufacturing debris - did you own it since new?

I'm with you on clean being the very best approach - no question. But this stuff is not an issue in the diffs. I've seen it on nearly every gear case I've ever drained for the first time. So, I like (and prefer) your perspective but I don't want people here thinking it's a cause for alarm or a manufacturing error is all....


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