Front Pinion Seal or Front Diff Seal (1 Viewer)

[Beast II]

I took my FZJ80 wheeling a few weekends ago just noticed that there is diff oil leaking from the back of the front pumpkin. The bottom nuts were also loose. Could this have loosened when the front shaft was over-stressed, from overfilling the diff fluid, coming down on a rock too hard, grease contamination from axle or do these gaskets just wear out over time ?

How do I tell if this has anything to do with the pinion seal ?

Thank you,

Matt

 

[landtoy80]

Is your breather plugged?

 

[Beast II]

Breather

I know where the breather is, but how do I determine whether or not its plugged ?

 

[IdahoDoug]

This won't be a breather issue simply because looking at the entire diff chamber as a unit, the easiest place for pressure to get out is the axle seal at the tips. To me, it seems just what you described - loose bolts on the rear diff cover. While not common, some folks here have found a few loose and it's simply from someone during the truck's life perhaps not torque-ing them down, or slight flexing from hard use. I suspect you can torque them to proper specs and stop the leak.

DougM

 

[Cruiserdrew]

I had this happen in Death Valley. If the 3rd member is at all loose, the torque causes shifting of the third member(differential) on the studs. That allows oil to seep past the paper gasket that sits between the third member and the axle housing. If you are really lucky, tightening the nuts to the proper torque will solve the leak. If you are not lucky, and you probably arn't, you need to pull the third member and replace the gasket, which requires the disassembly of the front end. PIA, but pretty straight forward. A leak at the pinion seal, the one time I had one, was pretty obvious.

 

[Beast II]

What will happen if the third member is loose ? Any way to diagnose this before I tear everything apart ?

 

[landtoy80]

You may want to drain the oil, clean up the outside with a carb, brake or starting fluid.
Get a can of Permatex Form-a-Seal
http://www.permatex.com/products/in...&product=Permatex, Form-A-Seal, Leak Repair
Spray the part that is leaking and tighten the bolts/nuts.

I have a can but have yet to try it but its worth a try.

 

[nyk438]

I had this same problem. Ended up having a dishonest mechanic at a gas station pull the paper seal that was already gone when I NEVER asked them to, just asked them to refill it with gear oil so I could get it home. Ended up taking it to LCS my local cruiser shop and they replaced all the inner axle seals and everything. Doesn't look likea pinion seal leak, there would be gear oil all over the crossmember I think or that bar that goes across the axle right under the third member where the front driveshaft connects. Oh and my nuts were loose as well.

 

[Cruiserdrew]

What will happen if the third member is loose ? Any way to diagnose this before I tear everything apart ?

Clean the oiled area really well with brake cleaner. Make sure you torque the nuts to spec. If the oil leak comes back, you should be able to tell where it came from. In my case, the nuts were a bit loose and the differential case shifted enough to tear the thin paper seal. Driving the 400 miles home, I had to stop and add a bit of gear oil every hour or so. The only fix was to tear it all apart and replace the gasket.

My theory is that the front differential on the 80 series is attached to the axle housing with 8mm studs and 12mm nuts. They do not develop the same clamping force as the 10mm studs and 14mm nuts used in the rear and in all previous Land Cruisers. Over time with heavy use, the third member can squirm a bit and eventually loosen the nuts. My advice would be to check those nuts at every oil change and make sure they are tight-spec is only 20 foot-pounds. Compare that to the rear tightening spec of 54 foot-pounds and 30% larger fasteners.

One last thing-check to make sure the drain plug is tight. I've seen them get unscrewed when you smack them on a rock.

 

[nyk438]

Thinking about it now, my vibration problems at higher speeds didn't start until I had first had the pinion seal replaced, and then had to have the paper one replaced. Needless to say I drove it a few days when I needed the seal to be replaced. Could my transfer case have moved a little causing my DS to not be straight? Could I just replace the rear driveshaft and that will remedy the problem or do I have to fawk with the transfer case?

 

[concretejungle]

Looks just like what my pinion seal leak looked like.

 

[Beast II]

OVERGREASING Knuckles

I made the mistake of fillng the knuckles with grease through the little hole. I filled them until no more grease would go in. I realize the mistake in my ways now and was wondering if this could have caused the leak in the front diff seal. Ie. Pressure from the grease bursting the axle seal and getting into the diff, contaminating the oil and causing a leak in the gasket ?

 

[concretejungle]

I am not robbie, but i think the seal just failed. Happened to me.

 

[landtoy80]

I used Amsoil syn grease when I put in my NewNewerNewfields.
I put in new axle seals and filled the cavity with grease.
Several months later I had dark grease. I changed the gear oil a couple times to clear out the grease.

The Amsoil grease is thicker and I think the grease worked its way past the seals when I pushed the birfields in.

I will go bect to dino grease next time I grease the birf's.

 

[Beast II]

Permatex Ultra Grey Silicon and Gasket ??

I'm replacing the diff gasket tomorrow. Should I use some Permatex Ultra Grey Silicon in addition to the gasket or just the gasket without anything on it ?

 

[cruiserdan]

The factory has you put it on dry. That is what I have done in the past. I imagine you could use a sealer but I do not have a specific recommendation.

 

[Beast II]

Thank you for getting all of the parts to me so quickly C-Dan.

 

[cruiserdan]

Any time sir.

By the way, your resistor left for you today.

 

[Bob_Garrett]

The factory has you put it on dry. That is what I have done in the past. I imagine you could use a sealer but I do not have a specific recommendation.

That's the way I always do mine on the 80 and the mini-truck and haven't had any leaks so far.

Bob

 

[Beast II]

Diff Sealant

That's good to know. I panicked a bit when I was taking it apart and saw some sealant around the housing. I put the gasket in dry as you guys specified, tightened all nuts to spec and then put some ultra grey around the entire thing. Should be ok right ?!?


Did the front axle service too. Those oil seals are a bugger to get in. I bent the hell out of one of them and had to get a comparable one at Napa - I bought 4 just in case. I bent two of them and finally got the third one in after sanding the sides down a bit. Whole job wasn't too bad - just very messy.