Weird debris in oil

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rtadams89
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Weird debris in oil

Post by rtadams89 » Sat Oct 16, 2021 10:07 pm

Today I helped a guy look over a Mule he is considering buying. It looks to be in generally good shape all over, but has sat unused for a long time. I went around and checked the oil in the drop axles; all were surprisingly full and clean except for 1 that was bone dry. Engine oil and transmission oils were a little low but also generally clean (or what you would expect). However, when we got to this plug at the rear axle housing, a little bit of oil -- maybe 1/8 cup -- came out and with it some weird chunks. I could be wrong, but I though this plug was supposed to be a drain for an area that was not supposed to have any oil in it. The chunks that came out look to be either a bunch of hard packed dirt or some sort of deteriorating rubber with copper/brass wires in it.

So first question: What is this drain for and how would oil get here?
Second question: what on earth are these chunks from?

PS: for size reference, those chunks are each smaller than my little fingernail.
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m37-man
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Re: Weird debris in oil

Post by m37-man » Sun Oct 17, 2021 1:42 pm

There are seals on the axle shaft in the upper part of the drop axle housing, see the drawings in the parts TM.

After 50 years the rubber of the original seals is probably hard as a rock, and comes out in petrified chunks. There is also a small spring in each one to keep the seal tight to the axle shaft. If the metal parts look like shavings I would be more concerned about that.

If you buy the Mule plan on going through the axle housings before you drive it too much, they are not that complicated.
M37-Man, discriminating collector of all terrain vehicles:
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'45 Willys MB
'73 Jeep Commando
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rtadams89
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Re: Weird debris in oil

Post by rtadams89 » Sun Oct 17, 2021 4:09 pm

Are those seals made of brass-wire impregnated rubber?

Chuck W.
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Re: Weird debris in oil

Post by Chuck W. » Sun Oct 17, 2021 6:51 pm

That plug is the bell housing drain and it is suppose to be dry. A small amount of oil, up to 1/2 cup is just from normal leakage. The pieces you found are pieces off the clutch disc, either from a previous failure or one in progress. Not really a bad thing, if the mule is is in good shape, replacing the clutch is an easy job. Dicker with the seller and get him to come down on the price to cover the clutch job..

m37-man
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Re: Weird debris in oil

Post by m37-man » Tue Oct 19, 2021 7:46 pm

The seals were mostly rubber or neoprene with typically a sheet metal backing plate and a coiled metal spring inside. I think the spring is steel but there are softer copper/brass parts in the axle housings which is why checking the innards is important.
M37-Man, discriminating collector of all terrain vehicles:
'43 Ford GPW
'45 Willys MB
'73 Jeep Commando
'78 & '85 Jeep CJ7s
'83 Jeep Scrambler
Herd of '66 BMY M274A2 Mules

Chuck W.
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Re: Weird debris in oil

Post by Chuck W. » Wed Oct 20, 2021 12:44 pm

but there are softer copper/brass parts in the axle housings
The only yellow metal parts in the drop housings are the bronze thrust washers on the intermediate gear.


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