Stinky Rear-end

Ok, this one has me stumped. The rear axle on my 03' is putting off a horrible gear oil stench. I replaced the pinion seal about a month ago and I cant find any new leaks. I have been checking the level every week but its not going down. I believe the axles is vented, so it could just be vapors, by why am I just now smelling it?

usually when you smell gear oil it means it getting overheated.. perhaps something is about to go.. i smelt it before mine went out but i had a replacement to put in so i wasnt to conserned..

What is about to go? The fluid looked fine when I changed it after replacing the pinion seal.

Make sure your vent is not plugged.

i would pull the cover off and inspect the gears for play/cracks/chips.. like joe said, sometimes when you smell something like that, the rear could be going.. if it's overheating, i suggest switching to a new gear oil

I will pull the cover off this weekend if I get the chance and check it out. The thing that is bugging me is why the smell is so sudden.

semocoachworks wrote:

Make sure your vent is not plugged.

Does the AAM 11.5inch 14-bolt have a vent? I looked for one but couldnt find it. Guess i'll just have to look harder.

yeah it should be on the left axle tube..

btw it should just be a vacume line running up to your frame or into your charcoal canister depending on where its located..

i believe all rears have vents.. i know all of mine were holding the rear brake line junction block against the left axle tube.. i think my s10 10 bolt is on the top of the pumpkin though

Yeah that axle should have a vent but I'm not sure that series of axle is alittle new to me! However like said before normally when your geal oil begins to smell it means it's getting over heated due to something out of adjustment. When you replaced your pinion seal you didn't mess with the backlash or the pinion bearing did you? Having the bearing preload off or backlash out of adjustment will cause catastrophic damage! When you drive does the rearend have a viberation? Not like a bad ujoint viberation but a very subtle smooth almost like a cell phone vibertion you'd be able to feel it in your seat but it wouldn't shake the whole truck. Also is you rearend louder then normal? If a rearend is adjusted properly you shouldn't be able to hear it at all but if the pinion is out of adjustment and is running to deep in the root of the ring gear then you'll get noise that sounds like a tire hum or like a gear drive hum having your pinion running deep into the root will cause the gear oil to get squeezed out of the mesh and the gears won't run as cool causing the oil to over heat. I hope it's not this but if it is then you may have to pull the rearend apart and reset the backlash and pinion depth If you axle has adjustable preloads like the 10.5 14blt then it won't be that difficult but still a PITA! Good luck bud hope you can get it figured out

No, I didnt mess with the backlash. Just replaced the seal, put her back together and filled it up. I havent noticed any vibration at all while driving. I've been checking the ground under the truck and there are no leaks. I am going to pull the cover off this weekend and see whats going on in there. Thanks for the input guys.

Yeah no problem Rob. I hope you get it figured out!

If ur rear stinks, WASH IT!

So it's Monday morning any updates?

Yeah, i'm broke, and so is my truck. I replaced the hub assembly last night and on the way home broke a brake line..... FML. I had the truck towed in and while the where at it look at the rear end..... turns out if was a cracked pinion yolk!!!!! I've never even heard of one breaking, but apparently I did it.

Yikes


At least it's not too hard to repair.

Not hard at all.... just another $400 in parts and an $80 tow.....

Yeah

how would the cracked yoke cause the smell though?>

The oil was leaking out past the crack.

gotcha

wow.. what a weird thing to break on a stock truck

Yeah that's what I was thinking! I've seen broken yokes on 1350 series 14bolt crawler axles(not in person) and that's why they upgrade to the 1410 series ujoints but on a stock truck that's crazy! Rob when was the last time you dropped your truck off a ledge and had the pinion hit first? lol But really how big was the crack because I think you'd've seen it when you replaced your pinion seal? Wait when you replaced the seal was it cold out? Because you may have cracked it putting it back on.

FaselZ71 wrote:

Yeah that's what I was thinking! I've seen broken yokes on 1350 series 14bolt crawler axles(not in person) and that's why they upgrade to the 1410 series ujoints but on a stock truck that's crazy! Rob when was the last time you dropped your truck off a ledge and had the pinion hit first? lol But really how big was the crack because I think you'd've seen it when you replaced your pinion seal? Wait when you replaced the seal was it cold out? Because you may have cracked it putting it back on.

Nope, no ledges.... I dont beat on my truck but I do work it. I've never heard of one of these cracking or breaking even in the motorsports world. I thought the u-joint would snap first.

I dont know how big the crack was, only big enough to let the fluid slowly leak out. When I replaced the seal I checked it over well and didnt notice a dang thing. I was in my buddies heated garage so it was between 60* & 70*