stubble

Hey all, just curious if anyone else has seen this issue. My front diff appears to be leaking from the drive shaft output. it's not enough to leave drips but the skid plates are oily. Having the dealer look next week. 60k on a 2011 460.

Valley101

Before going to dealer I would wipe it all down and then drive for a few days and check again. Unless you are sure it is differential oil, it could be oil that dripped down from a previous oil change and the wind blowing under your vehicle could move it around as it dripped. Would not hurt to do this. Might save a costly visit to your dealer.

Jacket

Or the diff breather could be clogged so that a rapid pressure change caused it to blow a bit of oil past the pinion seal.

But like Valley suggested, I would look for other potential sources first. The above isn't as likely on a 4 year old vehicle that doesn't see significant time off pavement.

stubble

Thanks for the replies. Pinion seal was funky and leaking. Cost about $400 to replace including another part (a flange of some sort that is nearby, not exactly sure.) That plus drivetrain fluid changes and brake flush totaled about $1500. But they gave me an RX to drive for a couple days to ease the pain.

Now I should be good for 30k on that stuff.

ninja250

Anyone had the same problem ? I began to feel a slight sweet burning smell, rear wheel driver side, it went away pretty quickly. Drove a few thousand miles, finally, after a 1600 miles drive it started to smell burnt oil. I got under the car and the undercarriage was all covered in oil. It has no strong smell, but probably because it has been there for a while already. It is not engine oil, as the level of the oil did not change for many thousands of miles. After removing the two shields I think I have identified where it leaks - driver side, front differential, pinion seal, where the drive shaft enters the differential. I have found a few videos how to deal with that on a Toyota car, but nothing Lexus specific. I suspect that the job is going to be the same or very similar - remove the front shaft, pry the flange and old seal, clean, put the new seal, assemble, drain, refill. Has anyone done this job already? Any new parts except for the pinion seal itslf and crusher washers?

Video for a different toyota/LX470 here:

A few pics of the issue attached. Oil is splattered on everything, it seems that it drops on the tray/shield and then the air carries it all along the undercarriage.

Acrad

I'm not remembering offhand a report of that one here. I'll have to search through old posts. This would definitely be a rare reported one anyway on the 460.

zippymbr

I just rebuilt the rear diff on my GX470 that had 270K and the pinion seal is a ***** to get out, and that is with the third member out on the bench. I have never seen the pinion seal go on a 470 or a 460 for that matter. Now the CV axel seals leak all the time if not perfectly installed and only the OEM ones have worked well for me. To get to the seal once you remove the driveshaft you have to remove the nut that is on the pinion flange. Then the pinion flange is hard to remove, I used a hydraulic puller since I was rebuilding the diff. You have to be very careful in reinstalling the flange and nut as it sets the preload on the pinion bearing. I would not try to just replace the seal as you could just ruin your pinion bearings by leaving the nut too loose or too tight. Watch this vid for clarification,

Acrad

ninja250

Thanks! I plan to pull out the seal (only) and to replace it. Why would you pull the bearings out? Do they get worn out and need to be replaced, too? RE not over-tightening the nut, I will count the threads and tighten it exactly to the same position as it was before.

Yes, this seems not very typical that the pinion seal starts to leak, but you can find videos for the 470 people fixing it, which means that this happens from time to time
I looked around and there is nothing else that seems to be leaking - I can try to wipe it all in the first place, also open the fill plug of the front differential and see if the oil is up to the level, if not refill and wait for further leaks. That may be the way to go before opening the can of worms which is the diff.

ninja250

Great stuff, thank you very much Acrad.
Any chance to know the torque for the bolts/nuts flange to the front shaft?

Also - 273 ft lb torque - the nut - this is serious.

Acrad

Check out bottom pic on post #50 here for all torque specs

https://www.clublexus.com/forums/gx-...l#post11135485

ninja250

So, I have removed everything - the shaft, flange and seal. And now - there was nothing damaged at first sight. Two problems arose:
- the seal I have put in is super super tight - when inserted (or better hammered in - through a pipe, not with a hammer directly, took over an hour) has 'developed' a lip. Not sure if leave like this or get another seal and try to put it again. I am inclined to leave like this as it is still very very tight. Not sure if this will leak, I hope not. One thing I am 100 sure - it will NOT fall out.
- I have watched a few pinion seal videos and they talked about grooved flange - my flange developed a groove and that may be the reason the thing leaks, not the seal itself. So, debating if I need to get a new flange now. Which is probably what I will do.
Any takes on the two items above? Any experience with the flange issue?

Pics below - the lip on the seal and the grooved flange.

tntcandy

I would personally replace the worn parts, as you already have it apart, no need to risk it.
Even if its not leaking in the beginning, the groove will cause a different wear pattern and I'm sure it will fail again.

Seen it too many times on other machineries that have seals and moving parts like axels or rams.

ninja250

Thanks - this makes a lot of sense and confirms posts from other forums and even other car brands - the groove on the flange is a pretty common occurrence and a cause of a oil leak from the diff. I would blame the flange quality on this.

So - next - off to ordering the part and exchanging all the damaged elements.
I also noticed other things - the torque is 275 ft-lb on the nut on the pinion shaft, but - when I torqued it back with a regular electric power tool, it went back into the position (where it was previously torqued) very easily. When I got to 150 fl-lb it was already over the position it has been previously torqued to. It almost seems that it was factory under-torqued. Not sure if this is/was a problem, because I don't see how it could impact the groove on the flange. Just an observation.

ROSCOGX470

The under factory torqued bolts may have been responsible for your leak. How hard would it be to replace the pinion bearing while performing the seal replacement? I may have a whine in that area that may be a worn pinion bearing in the front diff. I’m other words could a driveway mechanic handle a pinion bearing replacement.