Gear oil smell inside vehicle after gear change

[Steampunk]

Hello everyone. A month or so ago I had the differential gears changed on our 2002 TJ Sport, Dana 30/Dana 35. It had the original 3.07 gears in it and has 33" tires. I couldn't stand it, so I had the gearing changed to 4.56. Perfect for all around driving and off road trailing. Here's my conundrum: After the gearing was changed, I noticed the smell of hypoid gear oil (if you're familiar). There are no leaks. I did notice that the small valve on top of the front axle vent was gone, so I replaced it. No difference. It smells more going uphill under load. Has anyone else had this issue and if so, what was the remedy? I'm going to take it to the guy who did the change for me this week and see what he thinks.
BTW, I love the gearing for my purpose. I did do the break in procedure per Revolution Gears. I'm at about 600 miles and it's time to change out the oil, per Revolution Gears.

 

[hosejockey61]

Either they spilled gear oil and you're smelling remnants, or your diff is spitting out the excess (through the vent line) as it tries to find its happy spot.

Just my guess.

 

[JKP]

Did you check the rear axle hose/vent?

The rear is going to be the hot one if you're not in 4WD.

 

[Harold&Cat]

I had overfilled my front differential and the gear oil was walking up the front axles . Took a while for the smell to dissapate .

 

[Steampunk]

Either they spilled gear oil and you're smelling remnants, or your diff is spitting out the excess (through the vent line) as it tries to find its happy spot.

Just my guess.

I think it may be number three. Thank you!

 

[Steampunk]

Did you check the rear axle hose/vent?

The rear is going to be the hot one if you're not in 4WD.

No, I haven't. Tomorrow I will take a look. I was thinking it had to be. from the front, but that's a definite possibility. Thank you!

 

[Steampunk]

I had overfilled my front differential and the gear oil was walking up the front axles . Took a while for the smell to dissapate .

I'll check the level when I drain the old to install new. I know the gearbox was over-filled. Thank you!

 

[CharlesHS]

In warm weather I noticed that on my '01 4.0L w/ NV3550.
Took me a while to track down the odor, but I found that the inner shifter boot was ripped and the (4) shifter bolts were loose causing gear lube seepage.
I wiped down the seepage, tightened the (4) shifter bolts and replaced the inner boot.
No more odors... and that was more than three years ago.

 

[Steampunk]

In warm weather I noticed that on my '01 4.0L w/ NV3550.
Took me a while to track down the odor, but I found that the inner shifter boot was ripped and the (4) shifter bolts were loose causing gear lube seepage.
I wiped down the seepage, tightened the (4) shifter bolts and replaced the inner boot.
No more odors... and that was more than three years ago.

I will check that Charles. I didn't get to try anything today as it was raining and then this evening had a three hour bout with Afib. Probably Wednesday is my first opportunity. That boot could be a problem as our Jeep has a B&M quick shifter on it. Strange though, it never had the odor before the gear change. Thank you!

 

[AndyG]

Don’t be surprised if you need to wash down the undercarriage with degreaser a couple of times

That stuff has a stench….

 

[Steampunk]

My apologies for totally forgetting about this post. I drained the gear oil that was used by the shop that installed the new carriers and 4.56 gears. I refilled with Amsoil Severe Gear. Smell is gone, wife is happy. Well....mostly. Thanks for the tips and advice.

 

[GoldenGorilla]

Smell is gone, wife is happy. Well....mostly.

The best we can hope for.

For future reference if appropriate for your diffs, the synthetic gear oil without friction modifiers smells slightly less bad.