Source of Leak

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re: 1996 LX, 250k

What's going on here? It's both sides but the driver side seems to be a little worse.

IMG_0461.JPG
 
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Yep, Birf Soup. Diff Oil + Birf Grease.
 
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re: 1996 LX, 250k

What's going on here? It's both sides but the driver side seems to be a little worse.

View attachment 3040559
Actually looks like you never had any GREASE in the birfields, just gear oil.

There is an inner axle seal that is supposed to hold the gear oil in the axle housing. Then there is supposed to be a moly-fortified GREASE in the birfield housing (knuckle housing) and over time the inner axle seal fails and the gear oil mixes with the grease and you end up with birf soup and it gets all drooly and messy. Usually, the knuckle balls have gobs of grease stuck to them and they are very messy. Yours appears to be just a leak, indicating that maybe there was never actually grease in the knuckle.

Either way, time for a proper rebuild and service.
 
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Y'all have jump started my research. It looks like Youtube has it pretty well covered. I've had the truck for a year but put only a couple hundred miles on it, and have not touched the front axle. It's too hot here now for big jobs like this so I'll probably postpone until the fall. I should probably make sure it has some grease though, and gear oil.
 
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Three great videos on it below. Get the rebuild kit from cruiserteq.com, and probably an offset seal driver from wits end. You’ll see other specific tools in the videos, but it’s nothing very specialized. Definitely a “while you’re in there” job where everything gets refreshed, as it all comes apart and has to be cleaned anyway.





80 Series Land Cruiser Knuckle Rebuild - https://youtu.be/y08phFlezBs

Do your research here about specifics & extra tips, including the preload procedure and torque specs to use, as that’s a common thing that leads to having to go back in there.

Good reads to start it off

FAQ thread for knuckle rebuild

Preload tips & info (starts on a specific post)
 
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97 AZ LC: you can unscrew the inspection port plug located on the top front of each steering knuckle then take a long thin tool (screwdriver) and use that as a crude dipstick.

Put the stick in, pull it out; if it comes out with just pungent gear oil dripping off and not much grease then as mentioned above, your knuckles either had no grease in them (left dry by the last mechanic?) and gear oil leaked in from the axle housing and/or whomever last had the front axle apart filled the knuckles with gear oil (wrongly) instead of Moly grease.

Both scenarios have happened to other Mud members (no grease or gear oil instead of grease in the knuckles).
 
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More clues:

Found some service records - driver side front axle rebuild in 2015 at 227k. No sign that the passenger side was done. Same time frame - front diff fluid changed - bill shows 3 quarts of "front diff gear oil 5918915".

Pulled the inspection plugs on both sides, both sides showing only dark gray grease, no sign of a gear oil slurry, driver side looked low on grease, passenger side looked better. Closer inspection - passenger side is all caked up but doesn't seem to be actively leaking at present. Driver side definitely leaking because I remember spraying it down at the carwash a few months ago.

Could not get the front diff fill plug off, need to find a 6 point socket, will report back.

Thanks for the help.
 
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Pump grease in the knuckles through the inspection port and don’t drain the diff until you can get the fill bolt out. Always remove the refill bolt before the drain bolt. If you get enough grease in the knuckle and make sure the diff is full, this is not an emergency or even very important to “fix”.
 

roadstr6

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Check your front axle breather. It's probably clogged. As the diff heats up it's forcing diff oil past the seals. If you unclog it, problem may resolve.
 
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I got the front diff fill plug off and it took about a pint of gear oil, which suggests a leak since it was changed about 23k miles ago, but I can't be sure it was filled properly since I had never checked it.

I pumped some grease into the inspection ports, did the dipstick again so they both look good.

I pulled the front axle breather, not easy to find, doesn't seem to show up on parts diagrams. It's on the back side of the axle, driver side, maybe 18 inches away from the fill hole. I blasted it with some Brakeclean, couldn't really tell how plugged up it might have been, but it's completely clear now. It didn't look like something that needed to be replaced.

So I don't have any scientific results yet but I'm greatly comforted to know that I'm good on both gear oil and grease, for now. I'm going to clean up the driver side, really clean it up, spray it with some foot powder and see if I can determine exactly where the leak is coming from and how much. I'll try to remember to report back when I know more. Thanks for all the help.
 
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I got the front diff fill plug off and it took about a pint of gear oil, which suggests a leak since it was changed about 23k miles ago, but I can't be sure it was filled properly since I had never checked it.

I pumped some grease into the inspection ports, did the dipstick again so they both look good.

I pulled the front axle breather, not easy to find, doesn't seem to show up on parts diagrams. It's on the back side of the axle, driver side, maybe 18 inches away from the fill hole. I blasted it with some Brakeclean, couldn't really tell how plugged up it might have been, but it's completely clear now. It didn't look like something that needed to be replaced.

So I don't have any scientific results yet but I'm greatly comforted to know that I'm good on both gear oil and grease, for now. I'm going to clean up the driver side, really clean it up, spray it with some foot powder and see if I can determine exactly where the leak is coming from and how much. I'll try to remember to report back when I know more. Thanks for all the help.

There is no need to find the leak. It can only come from the inner axle seal, they age, leak easily, and the surface of the axle shaft will have some wear by now, a perfect seal is possible but not really that important. Also, IIRC the fill level is not to the overflow level on the fill plug, rather a bit lower. When filled that high it will leak into the knuckles more readily. No need to fix it, it will sort itself out. I would put this on a list to do when other work is necessary, ie a major brake job.
 

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