A couple in my neighborhood have an ’04 DII with only ~85,000. I’ve helped them out before, reading codes for them. An afternoon doing Option B is in our future.

Recently they called with another issue. They reported a strong smell of gear lube after a 200 mile road trip, and when he looked under the truck there was a lot of gear lube on the right-side frame rail and on the handbrake drum.

I walked down the street to take a look, and unfortunately he had already wiped off the gear lube he could reach. Given the location of the leaked lube, it seems obvious it is coming from the transfer case.

I talked with him about the bottom (inspection) cover gasket being a known, common problem, but because he had cleaned up everything he could reach it wasn’t obvious that was the source.

Then, walking home, it occurred to me that a leak of the amount reported may be coming from one of the output shaft seals. Now that I think about it more, I expect that’s the case.

I advised him to drive the truck more to see if the source of the leak will be easier to see once more oil finds its way out of the t-case.

What do you guys think? Does the size of the leak and where the lube ended up indicate the rear output seal more than the bottom cover gasket as the problem? Thanks.

 

Well there is an output seal for the transfer case basically inside the handbrake, not really but yo need to pull the hand brake to get at it. But check the transfer case oil level, before they drive it no gear oil and that thing will eat itself.

 

^^^ I had this problem last year. I noticed fluid leaking out of my parking brake and then a few days later noticed a spray pattern of oil all around the frame and unbody. The output seal nut backs off over time. Easy fix, just remove the rear driveshaft and parking brake drum, and you have direct access to the nut. I'd clean off the parking brake drum and retighten the parking brake if it needs to be tightened. Took me ~45 minutes total.

 

check to see if the transfer case breather tube is still attached to the fire wall and hasn't fallen onto the exhaust manifold - if that happens it can melt shut and then the tcase will build up pressure and blow the gear lube out - happened to me on my D1 and case self-destructed while driving from lack of gear lube

 

Wow. Worth a try. Certainly better than diving in to replace the seal.

We should always start with the least invasive, least expensive solutions, unless like head gasket repair in a bottle, there is a reason to not do so.

We were not expecting this to be a DIY solution, but we could try to tackle what you described. The owner is in his late 70s, and doesn't have much appetite for DIY at this point, but I may be able to talk him into trying this in my garage. There is little to no downside in trying, it seems.

I'll wait for other responses too, but barring any other persuasive response I think this is worth a try. Thank you.

 

You may be able to access it without removing the parking brake drum, but I decided to just to clean out the excess oil and tighten up my parking brake. All you need to do is remove the rear driveshaft if you don't need to remove the parking brake drum. Not sure if you have the factory roto flex or an after market drive shaft, but the hardest part imo is getting the driveshaft off. A good shop should be able to do this within 1-2 shop rate hours. Not sure what it is in NC, but where I am its $150+ per hour for a LR shop. So I try and do all the work I possibly can myself.

Glad I could help! I had to phone a friend for this one last year so I'm just passing along the knowledge.

 

Also verify his vent lines didn't melt and are blocked allowing the TC to build up pressure inside and leak gear oil from the seals.