Mysterious Undiagnosed Burning Smell (1 Viewer)

[dickson1kyle]

Hoping someone can shead some light on an issue... I have a 2008 LC with 180k miles, and recently I've noticed a burning smell coming very specifically from the rear passenger side area near the wheel (you smell it when walking by the rear wheel well and passenger door). I looked at it myself and took it to two shops, all with no diagnosis. No fluids are leaking, the calipers are not locked, there's no heat in the wheel area at all that would indicate it's braking-related (other than maybe the E-brake I suppose, but wouldn't the caliper be locked up?), and it's not throwing any codes. It started soon after I had the radiator and hoses replaced, but any newnest would have burned off by now, and it's not remotely in the same location. And when it's on a lift and you're under it, it's clearly coming from higher up than the wheel - moreso slightly forward from the wheel area and apparenly from somewhere else.

As I said, not one drop of fluid is leaking, it's running perfectly with no noises and nothing that's a usual culprit like a stuck caliper seems to be the issue. Everything looks good mechanically under the truck. I'm hesitant to drive it any significant distance, and I certainly don't like the general idea of driving it out until something goes wrong (let alone catches on fire).

Could it be an axle, maybe something in the muffler/exhaust getting old? Could it have anything to do with replacing the radiator even though it's on opposite ends of the truck?

Has anyone experienced this?

 

[unclemat]

Dragging brakes?

 

[TeCKis300]

Wheel bearing?

In that area also has heater hoses and A/C pressure hose. Though leaking fluids of that type don't usually result in burning odors?

 

[RET2]

Water intrusion in door jam area?

 

[dickson1kyle]

Thanks for the replies! It's totally dry of fluids and water. Tested the e-brake and it's fine, and the calipers are not locked or rubbing. Neither of the garages believe it's anything with the wheel or braking function.

The burning smell is very mechanical, it doesn't smell like fluids (and there aren't any leaking, bone dry under there).

 

[RET2]

Thanks for the replies! It's totally dry of fluids and water. Tested the e-brake and it's fine, and the calipers are not locked or rubbing. Neither of the garages believe it's anything with the wheel or braking function.

The burning smell is very mechanical, it doesn't smell like fluids (and there aren't any leaking, bone dry under there).

Start and let idle for a period to weed out mechanical source? Enlist another sniffer to help find source?

 

[bloc]

Mine has done this from time to time, usually pretty subtle and at the rear, and almost always after a long highway stint. Over the years I feel like I've seen others post about it on occasion too. This is over 100k miles of ownership.

I never have figured it out, and just about everything in the rear has been replaced.. shocks twice, both axle bearings, brakes two or three times, including full parking brake internals once.

Wish I could figure it out but I never have.

 

[dickson1kyle]

Mine has done this from time to time, usually pretty subtle and at the rear, and almost always after a long highway stint. Over the years I feel like I've seen others post about it on occasion too. This is over 100k miles of ownership.

I never have figured it out, and just about everything in the rear has been replaced.. shocks twice, both axle bearings, brakes two or three times, including full parking brake internals once.

Wish I could figure it out but I never have.

YES! That's mine too. All new brakes, calipers, and bearings.

 

[Sandroad]

Mine does that too. Slight oily hot smell in rear wheel wells when it’s worked hard. It doesn’t really take much heat on a tiny bit of grease/oil to smell hot. I’ve looked carefully and nothing is wrong. Maybe just a hint of greasy sand from greasing the u-joints on mine or maybe just a tiny spot of grease flung on the exhaust or maybe just a warm differential. Anyway, if nothing obvious is leaking it’s not something to keep in your worry box.

 

[ryanCA]

is it possible you have a leak underneath which splatters when you drive, and as you pull over you can smell it?


Mine at 270k miles starting smelling from front tire - oil

led me to change valve cover gasket (not cam tower leak as initially suspected) and smell and hot smoke all went away

 

[RET2]

Mine has done this from time to time, usually pretty subtle and at the rear, and almost always after a long highway stint. Over the years I feel like I've seen others post about it on occasion too. This is over 100k miles of ownership.

I never have figured it out, and just about everything in the rear has been replaced.. shocks twice, both axle bearings, brakes two or three times, including full parking brake internals once.

Wish I could figure it out but I never have.

Have you tried finding the source with an infrared thermometer?

 

[liv2bike]

I get this smell occasionally. As mentioned above, it’s usually after highway driving or going up and over mountain passes when she’s been pushed a little. It’s like a burning rubber smell. I’ve given up trying to figure it out. It’s been doing it for years.

 

[vipergrhd]

Did any of you check the vents on the diffs. and transfer case? Just my 2 cents.
Maybe it's venting out?

 

[Sandroad]

Did any of you check the vents on the diffs. and transfer case? Just my 2 cents.
Maybe it's venting out?

^^^ This. I suspect it may be fumes from the breathers. When the gears get hot the breathers would vent and the smell is similar to gear oil.

 

[EverywhereBear]

I had this issue on my 2018 LX. But the smell was on the driver side rear wheel. It ended up being an issue with the parking brake. I can’t exactly recall what the issue was. Also, I believe the parking brake system on the 16+ are different than on your 08.

 

[bloc]

Have you tried finding the source with an infrared thermometer?

Yep, nothing out of the ordinary.

 

[RT Cruiser]

The smell is coming from one of the TENOK sensors. You ask what is this? Great question. This is the Toyota-Engineer-No-One-Knows sensor. The Toyota engineers did something so strange that not even they know what they did. Although these sensors are located on various parts of the 200 series, they are incredibly hard to find. The good news is no matter what reading or smell they provide, the sensors do not impact your rig one way or another. If the smell is coming from this TENOK sensor, you're good to go.

I have a 2008 with 318,000 miles. I've smelled those TENOK sensors before several times and learned to smile and count my blessings she's still running strong.

 

[manofthewoods]

Did any of you check the vents on the diffs. and transfer case? Just my 2 cents.
Maybe it's venting out?

I had a smell like the OP's description.
Turns out my center diff fill plug was not very tight (my fault), and a drop would leak on the exhaust and burn. Almost a plastic type smell. Never a drop on my garage floor.
Weird