Still dealing with a rotten egg/burning grease smell

Ozark Bushwalker

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I mostly smell it after a long drive when I open the window, I thought it was coming from the engine bay but I'm not sure.

It improved somewhat after tearing off the hood insulation, but it's come back with a vengeance. I topped up the trans fluid too and no change. Doesn't seem to be coming from the brakes either.

It's vaguely like a mix of rotten eggs and burning grease. Haven't noticed any grease on the exhaust though, could it be built up crud and oil on the block burning off? Or maybe oil or steering fluid leaking onto the engine?


Another theory I had was the cats plugging up, possibly with oil from the valve stem seals. Would a high flow cat fix that? What seems most likely here?

Thanks
 
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I mostly smell it after a long drive when I open the window, I thought it was coming from the engine bay but I'm not sure.

It improved somewhat after tearing off the hood insulation, but it's come back with a vengeance. I topped up the trans fluid too and no change. Doesn't seem to be coming from the brakes either.

It's vaguely like a mix of rotten eggs and burning grease. Haven't noticed any grease on the exhaust though, could it be built up crud and oil on the block burning off? Or maybe oil or steering fluid leaking onto the engine?


Another theory I had was the cats plugging up, possibly with oil from the valve stem seals. Would a high flow cat fix that? What seems most likely here?

Thanks
Sounds to me like a gear oil drip from a differential or knuckle that's hitting the exhaust and burning off.

That oil has a high sulfur content and it smells nasty anyway. Especially when hot.

Inspect your RF knuckle.
 

Ozark Bushwalker

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Sounds to me like a gear oil drip from a differential or knuckle that's hitting the exhaust and burning off.

That oil has a high sulfur content and it smells nasty anyway. Especially when hot.

Inspect your RF knuckle.
I don't see any leakage on either knuckle. Bearings were replaced a couple years ago. Haven't noticed anything on the diffs either.
 
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I don't see any leakage on either knuckle. Bearings were replaced a couple years ago. Haven't noticed anything on the diffs either.
Check the T-Case as well.

I had an issue that I got grass into the seal area around all of the U-Joints on both the T-Case and the pinions. It caused all of them to leak for about 3 moths as it wore the grass out of those areas. Any little drips would platter on the bottom of the truck in a stripe perpendicular to the driveshaft and would contact the exhaust.

Look under the truck for telltale signs of a leak that's being slung by a rotating part.
 
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Rotten eggs = gear oil
 

Ozark Bushwalker

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Yea I hadn’t noticed heat oil getting flung around but I haven’t been under there while the truck is running either.

It’s not possible for the cats to cause a simile smell?
 
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Yea I hadn’t noticed heat oil getting flung around but I haven’t been under there while the truck is running either.

It’s not possible for the cats to cause a simile smell?
Yes, that is very possible.

If you're buying cheap gas (87 octane E-10/15) and buying from certain vendors, yes that's VERY possible. Depending on their supplier, some gas stations use a higher sulfur content gasoline and you get a significant rotten egg smell when driving. I only use the following gas stations when I travel in order to maintain my fuel system and avoid the rotten egg smell:
QT (QuikTrip)
Caseys
Love's

Shell gas stations have actually shut down because the sulfur content got so high in their gasoline that it caused system malfunctions in cars.

I would say this is a very distinct possibility.
I know I would usually encounter this as I travelled north and east. Not sure where you went, but it does tend to be a regional issue.
 

clx16

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Leak out of your transfer case seals will spin and throw gear oil on your exhaust
 
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Yea I hadn’t noticed heat oil getting flung around but I haven’t been under there while the truck is running either.

It’s not possible for the cats to cause a simile smell?
Why do you want it to be the cat's?

Way more likely it's from the transfer case.
 

Ozark Bushwalker

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Yes, that is very possible.

If you're buying cheap gas (87 octane E-10/15) and buying from certain vendors, yes that's VERY possible. Depending on their supplier, some gas stations use a higher sulfur content gasoline and you get a significant rotten egg smell when driving. I only use the following gas stations when I travel in order to maintain my fuel system and avoid the rotten egg smell:
QT (QuikTrip)
Caseys
Love's

Shell gas stations have actually shut down because the sulfur content got so high in their gasoline that it caused system malfunctions in cars.

I would say this is a very distinct possibility.
I know I would usually encounter this as I travelled north and east. Not sure where you went, but it does tend to be a regional issue.
Hmm do you get the stuff with no ethanol? Or the 10% from the stations you listed?
 

Ozark Bushwalker

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Why do you want it to be the cat's?

Way more likely it's from the transfer case.
Just open to all possibilities. I imagine the TC would be a cheaper/easier fix anyway.
 
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Hmm do you get the stuff with no ethanol? Or the 10% from the stations you listed?
I use both, but the majority is the E-10, but I also run the 89 octane in my LC. I drive hard and I CAN tell the difference. If the no ethanol is available and is within $0.15 of the E-10, then I will use the no ethanol.

If I'm in a rental, I still run the 87 octane E-10/15, but I still choose the gas stations accordingly because I don't want to smell that when I'm in a truck for 14 hr/day.
 

clx16

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Couple weeks ago that was my plan when i pulled the viscous coupler out and put in a correct size speedo gear. But mine were dry. My speedo gear seal was leaking pretty badly though. I didn't change it, but it doesn't look too bad to do. I am just trying to stop fixing things that arent broken.
 
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Ozark Bushwalker

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Search didn’t turn up much. Any ideas of the cost to fix it if it does turn out to be the TC?

I’ll try runnning 89 or ethanol free and see if it makes a difference.
 

clx16

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To be clear the seal of concern would be to the flange holding the rear driveshaft as that would be the flinger. The other one to the front i don't think can fling on the exhaust due to the TC being in the way
 
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Search didn’t turn up much. Any ideas of the cost to fix it if it does turn out to be the TC?

I’ll try runnning 89 or ethanol free and see if it makes a difference.
Dude. Go inspect the transfer case, especially spots like where the speedometer attaches.
 

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