yeah, diff oil is very stinky

^This is what I'm thinking of too. I did one time smell the diff and it seemed like it's coming from it. I did track my stock diff pretty hard that day and it was hot as hell. Knowing diff oil smelled the worst...I think it's closer to that than anything. As for everything else, i'm not sure. The smell didn't change since the track day. It incrementally got worst throughout track day from 3/4 of the day. Then when I parked it in my garage it just got really really bad.

As for my CAT setup (Test Pipe or HFC) I've had it like that for a long time so I don't think it's that. It doesn't smell like what an old Muscle car that's running really rich. Like if I close the garage with the car inside, after 15-30 mins, the garage would be filled with this nasty smell.

funny thing was the first day i discovered this, I started cracking bottles of Motuls sniffing everyone of them....sigh. I might need to bring the car into a mechanic with all interior stripped. Definitely not the GT Mat, I stripped the darn trunk. Still stinking up the garage.

are you using the exhaust canisters as a rear lift point? :wtf2:

:icon18:　nono, his car is already on jackstands. i think he's using that to support the weight while he undid the flanges to the rear section.

It almost has to be the diff fluid... That stuff smells HORRIBLE when it's fresh. I can only imagine what it would smell like when its burnt. :eek:

i'd like to see that happen ...lol

Problem solved...

Just got a call back from the mechanic. Yep it's the diff oil being burnt after tracking really hard on a very hot day. They had to change it twice to reduce the smell of it.

Man, crazy! I even upgraded from Redline to Motul a couple of days before track.

You drive too fast!

Well,
The "real" Scruffydog knew where it was coming from, and tried to tell you but you wouldn't listen.....

Maybe it is time for a Quaife diff.

I have a friend with a 350Z who was burning his diff fluid every track day.
It was so bad that he was changing his diff fluid at the track before he went home.
(BTW he is a HPDE Instructor and a mechanic that specializes in Zs)
He also started going through right rear wheel bearing on a regular basis.
He upgraded his diff to a Quaife and both problems went away.

I plan on installing a Quaife Diff sometime next year.
Every one I talk to that is big into track and/or autocross have one.

It is time to upgrade the diff, but I just bought a new car for the wife to be. So I need to hold off on modding the Z for awhile.

http://i358.photobucket.com/albums/o...psb80d0129.jpg

The smell is still pretty strong still (still stinks up the garage but took an hour instead of 15 mins). A buddy told me that I should find the Vent tube that comes out of the diff, follow it till the end, and find the residue from the vented tube. Supposedly when the diff gets overheated, it goes out of this vent tube at the top of the diff cover and kinda goes into an open space in the left rear section of the subframe next to the rear diff bushing. (which explains why when I smelled the bottom of diff case, it's not very strong, rather it's all over the place).

Wish me the best of luck, still gotta fix it myself. Turns out the mechanic didn't really do much for me. $ down the drain.

Man, I hope you get this resolved, its awful to think the diff oil vents into an area where you cant get to then you just have to live with the smell forever.

Duct tape a straw to the vent out the back! :icon14:

So last weekend I jacked up my car and hosed down my entire rear suspension arm, differential housing, exhaust, pretty much the whole cavity of the rear. I did notice the over flow tube that ones out of the differential ends at one of the main structural cross member over the differential. It almost looks like it goes inside the hollow member. So what I did was forced water (no soap) thru it and hosed down as much as I can. I ran out of brake cleaner.

Long story short 75% of the smell went away!!! Super happy but when I park the car I can still smell the burnt oil residue. Its been another week already since, maybe I just need wash that area again with gunk or brake cleaner. Better yet have someone steam clean the car.

I'm going to track again in September at Laguna, hopefully I won't have to deal with this issue again. Sigh