Gear oil smell no leaks

Help needed on my 300k 1997 3.4L manual taco...
I'm smelling very strong, nasty whiffs of gear oil while driving, but no visible leaks. It started after changing the fluids in the transfer case and differentials, months ago. No smell in the cab, only under the truck body. Oddly enough I smell it when depressing the clutch. New clutch as of a week ago, thinking maybe I smelled the clutch slipping, but that wasn't it. No visible leaks. Any ideas?

 

Have you replaced the valve cover gaskets? They could be leaking, mine does and you can smell the oil. They're getting replaced soon

 

Valve cover gaskets replaced about a month ago. What I smell isn't that oil though, it's gear oil. The nasty pungent smell

 

It might be just from whatever spilled out when you did the fluid change. The nasty smell is sulfur in the gear oil; its there as a pressure additive. If its just from spillage it will get weaker over time.

 

When you roll your window down does it smell like you are driving near a cow pasture?

 

As things warm up with warmer weather pushing fumes out the vent perhaps.

Do you smell it when parked ?

There are many smells worse then gear oil it smells good to me any more

 

I had a trans shop overfill my manual trans with gear oil when they replaced the clutch. It smelled like gear oil bad inside my truck when the trans heated up on a long drive. Could smell it from the shifter area.

They were able to overfill it because they filled it from the top (not using the fill hole on the trans). Did you recently change your fluids or did a shop do it?

 

I recently did all my gear oil swaps and smelled it just like you, maybe not so bad. I'm 99% sure its just whatever you spilled. As you know that smell is strong and unmistakeable.

 

It will fade, mine stunk for weeks when I first changed the trany/transfer and differentials.... the stink kinda clings to everything, like if you run over a dead skunk. Get a little green tree ... lol

 

My 2014 has this problem also.

No leaks and it is definitely gear oil not motor oil.

I am the only person that services this vehicle and I am certain that it is not over serviced

 

Well it's been over ayear now and I still can smell the gear oil. And still no signs of oil leakage anywhere underneath the truck or in the engine compartment. Funny thing is, during last winter I didn't smell it at all...

 

Warm/hot weather makes it smell more I bet, makes everything smell more lol.

 

torn rubber manual shift boot

 

The gear oil smell usually hangs around for a little while. When I did mine, I cleaned as much of the gear oil off as I could with brake clean but there was still a hint of the smell which went away gradually over time. Just keep an eye and make sure you have no leaks.

 

Does anybody have any more insight on this one? I changed all my gear oil earlier this summer (front and rear diffs, manual trans and transfer case), and I have the exact same issue. I especially notice mine when I'm under load at altitude, ie going up steep hills. I'm not getting any leaks, and I filled them from the side ports. I measured my oil per the owners manual to make sure I didn't overfill. It's been several months but still very noticeable... it's driving me crazy.

 

How are the breather caps and lines? Did you do a rear diff breather relocate?

It's also possible you just used more volatile gear oil with more sulfer content than the previous oil. I notice Castrol synthetic smells worse than Lucas or Pennzoil/Quaker/Shell synthetic, for example.

 

I did the rear breather mod as well, and located along the gas filler neck under the bed (I didn't bore through to the gas cap). Front breather was still fine.

 

I feel like I can smell it coming from the my shift lever - I've yet to tear apart my center console.

 

Spilled some gear oil on the carpet about 6 years ago. When the heats on blast it stinks sometimes. lol You might have too much in there and it's making it's way out the shifter area.

 

Might be a cracked transmission breather line?