Topic: Gear Oil Smell

[83MT]

I got my truck (with rebuilt engine & new L52HD) up to highway speeds for the first time yesterday. Drove out to a friends to return tools. On the way back home, and again this morning I noticed a pretty strong smell of gear oil. I did a search and it looks like it could be a transfer case leak? mabye getting onto the exhaust? Although mine isn't a burning gear oil smell, just hot gear oil. I guess I should be looking for leaks? Whatever it is, I haven't noticed oil spots on the ground, so I can't be leaking too bad.

[Rocksurfer]

Check the shifters, it's the most common area for a leak, or you may have overfilled it and it's coming out the breather.

[83MT [OP]]

Alright thanks, I'll check that out.

[OOPS]

Do you have the boots on the shifters?

[Joey88RUNR]

yea mine is coming from the shifters too

[83MT [OP]]

Yup, I do. I'll open up the fill plugs on the tranny and t-case this weekend & see if I get some overflow.

[83MT [OP]]

So, I drained excess fluid out, made sure everything on the shifters was tight and that the boots were on. Still a very strong gear oil smell. Would just a small leak somewhere else cause it to smell so strong? I know my front diff is leaking a little, and I heard from a mechanic that my t-case rear output shaft was leaking. The front diff leak will leave a 2-3 drip puddle under the truck if it's parked longer than 3 or so hours, but that's it. No noticeable leak from the t-case. Would a leak out of the shifter area need to be noticeable to smell pretty strong? I tried looking on top of the tranny & t-case and it doesn't look wet at all.

[RABIDYOTA]

you said new trans  the heat of running the truck could cook off the oils on the out side of the trans case  L52 castiron right  cast iron has to cure just like a skillet

[jimbo74]

yeah, im thinking its fine..... jsut let it get warm for a bit... if its still stinky after a week, then start investigating

[83MT [OP]]

That's actually interesting. Hadn't thought of that.
But, I've been driving it over 400 miles now; almost time for my first oil change. Should it still smell? Maybe I'll do like my skillets at home & just use bacon grease to cure it! No good in bear country, though...

[RABIDYOTA]

only if you bait with you'r truck just don't sleep in the bed!!!

[83MT [OP]]

So I changed my fluid for the first time, and put in GL4 instead of 5. I took it on a 2 hour trip. I don't smell it at highway speeds. Just getting sucked away by the air flow instead of coming in the cab? Or could GL4 instead of 5 make a difference? Also, I do have a front diff output shaft leak, and a t-case output shaft leak. Would those little leaks be enough to stink up my cab?

[BUDDERS]

Yup, especially is that front diff output shaft is flinging gear oil up onto hot engine parts.

[83MT [OP]]

Alright thanks. Driving it this morning, I don't smell oil yet, so maybe the highway trip did something....
After that trip, and having the inner axle seals replaced (although I don't see why that would have anything to do with it), the front diff leak is much worse, so I guess I'll be getting to that next anyways.

[8D3TOY]

Just changed all the gear oil in my 83, trans, Tcase, and diffs and I also got the heavy gear oil smell but no leaks.  It is gone now but had me worried.

[83MT [OP]]

Yeah, I never smelled it before I changed all the fluids either. I guess if you spill any on the gear boxes it's got to cook off, but I don't think that was my problem. I've been driving it around town for about a week now and no gear oil smell! That's nice. I ordered the pinion seals and nuts for my diff and t-case leaks, and got my front diff breather working again. It was clogged. After I get to that stuff....I should be completely leak free on this truck.

[BUDDERS]

Yeah, if your diff breather is clogged, that gear oil will find the path of least resistance and start spewing.  It happens because of the pressure increase inside the axle housing assembly once everything starts heating up.

[Cheesemaker]

My read diff breather was plugged and I fixed it with a hose barb, hose and a cheap fuel filter!  Up high and out of the way!  All for less than $20.  I hated the smell of gear oil on the muffler!