Leaking Knuckle Grease on 4WD Toyota = Clogged Differential Breather
Over time the seals will start to leak grease and if the moly grease in the knuckle gets too low, the birfield joints will wear excessively. My neglected 80 only had about 85,000 miles when I bought it, but because the previous owners let the grease get too low, both left and right birfields were clicking on sharp turns.
One common cause for leaking knuckles actually starts with a clogged differential breather.
When the axle and gear oil warms up from the friction of normal driving, they expand and the warm air can escape through the diff breather. When that is clogged though, the next path of least resistance are the oil seals on each axle. When gear oil gets pushed past the seals, oil mixes with moly grease in the knuckles, making it thinner and more likely to leak. Also when the axle and the air inside it cool and contract after parking, air can’t enter through the breather, so the mix of gear oil and moly grease gets sucked back through the oil seal, into the axle and differential. If you change the gear oil and it looks like army green brownie batter, this is probably the cause.
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Great video. Very informative. I’m rebuilding my ‘77 FJ40 now and it is great to be on the lookout for keeping the breather clear.
If you're going to be offroading often, consider running a longer line up to the firewall. The previous owner did something similar on my 85. They ran a hose up to the engine bay firewall and stuck a fuel filter on the end. Cheap and it definitely works!
Great video! I recently rebuilt our 85 60 knuckles. I watched the video you did on rebuilding them 3-4 times. That one is excellent. Thanks for putting together such good content.
Nice video, looking forward to the next in. 👌🏻Definitely worth doing the rebuild with Toyota parts and Japanese bearings. When I rebuilt my 85 axle the first time I was a poor student and used Chinese bearings. A few years later when I got a job I re-did it with proper Japanese bearings (from Marlin, I think). Now I have the old bearings as spares…. Which I’ll probably never use. There is a way to remove the knuckle to service the birfields without touching the wheel bearings, it’s called the “Camo” method, after a guy in the Pirate4x4 forum. You remove the steering arm, lower knuckle bearing cap, locking hub, knuckle ball seals and caliper and the knuckle can be removed. It’s heavy, though, but this is used as a trail fix when you break an axle.
I never knew of the camo method... thanks!
I used to pull off the breather lines and re-tube them to a higher point. They handle deeper water with out having to depend on a check valve that came over with Columbus. In fact, I used to ditch them (the check valve) entirely, and just candycane the end of the line.
The previous owner did something similar on my 85. They ran a hose up to the engine bay firewall and stuck a fuel filter on the end. Cheap and it definitely works!
Awesome video, quick and helpful. My knuckles are starting to show signs…..very soon the knuckle rebuild will have to happen.
Today I learned something new! Thanks for the tip.
Excellent info and presented very well, thank you for putting this together and sharing!
Good video, and really nice graphics. That gear oil and grease looked nasty. I recently removed my vent and cleaned it, (mud plugged)
Thanks! So just simply cleaning will unclog the breather from all the grime?
Yes, just keep it clean. The problem is they get covered with mud and they're so hidden that it goes unnoticed.
I dont own now?, but who would think??? Looks like there should be an elbow and face it to the rear of thr truck.🤔