Hot rubber smell after climbing hills

The last leg of my drive home from work takes me up some fairly steep hills over the last few miles. When I stop at the mailbox I usually notice a smell from the engine compartment that smells like hot rubber. It's a faint smell and there is no sign of smoke.

The really weird thing is that I've had two Tacomas and both of them have done the same thing. The first truck was a 2005 four cylinder two wheel drive, the current one is a 2013 V6 4X4.

When I noticed it on the first truck I assumed it was the serpentine belt heating up and changed it out but the smell persisted right up until I traded the truck. The newer truck does the same thing. I probably look strange sniffing around by the front tires and anything else I can think of that could possibly smell like heated up rubber and I never find anything. I've even shut the truck off and reached in to see if any of the pulleys feel hot but nothing, and no sign of rubber dust.

Has anyone ever noticed such a thing or have an idea why my Tacomas both smell like that?

Thanks,
Matt

 

Mine had the burning belt smell after heavy/full throttle due to the tensioner allowing the belt to slip.
Check all the idlers and tensioner and look at the belt plus spin the compressor, PS pump, and alternator and see if smooth and not rough/grating.
Had 155k miles and 10 years old when happened.
Changed all the idlers and complete tensioner assembly with a new belt and did alternator same time.
Just a note that to change tensioner (whole assembly) requires pulling the alternator and unbolting the AC compressor so takes a few hours.

 

And it's a right PITA.

There's one AC compressor bolt that is impossible to get to and get leverage on amd naturally it's the tightest.

Do your VVT-i screen baskets while you're in there.

 

Thanks for the information. As my wife likes to say often, "timing is everything". I had the compressor replaced in July and had a new belt put on then, that project set me back over $900. The alternator wasn't charging as it should so that is fairly new as well. There was no way I could wrestle with that problem on my own then or now. Had I been able to do the work myself I probably would have checked the pulleys and such myself.

The smell seems to come from the right side of the truck so I'm beginning to think the P/S pump might be the culprit. The 2005 had idler pulley problems and the alternator replaced when the mileage got high and the smell never went away. I never messed with the P/S pump on that one either.

I should develop the habit of checking into "what else can I do while X is going to be off the truck?"

 

My '05 has done that since new on the steep last leg of the road to my driveway. Never liked it much, but never caused a problem that required fixing...at least not yet.

 

That was my experience with my 05 and I drove it for 6 years that way. I did change the belt early on because it was getting noisy and the new belt lasted until I traded the truck in. I don't remember if the smell got worse when the alternator bearings started growling or not.

I usually just keep an eye on the belt and listen for any sounds coming from the pulleys and deal with them if they start making any noises. As far as the P/S pump, compressor and alternator I use an old time method to listen to them, I use a piece of old broom handle or a piece of hose to get a close listen for any unusual grinding.

The only reason I even asked the question was because I was climbing a very long, steep grade and pulled off onto the shoulder of the road to check for a cell signal and got a strong smell of burned rubber. I had the heater on high and I think the breeze wafted the smell right into the intake.

I had the oil changed about 200 miles prior and now I'm suspecting they dripped oil onto the belt (no garage to work in right now and a foot of snow and temps in the teens makes outdoor work suck). I hadn't thought about the oil drip possibility until just now. I've been so busy and had so much crap on my mind I had "forgotten" about the oil change.

IMO that upside down oil filter on the top is about as good an idea as getting rid of the transmission dipstick is.

 

Maybe your motor mounts are shot and when you're under heavy torque load from going up hill it's twisting the exhaust into the power steering lines?

Only other thing I can think of is there's a breather line for the transmission and transfer case that goes up the passenger side and could have popped out of its retainer and is touching thr exhaust and the smell is traveling up the tunnel into the bay?

When I did my clutch I noticed the breather lines had some burn marks and replaced them.

 

Just thought I would give an update.

A few days after posting this I took the truck to a local garage owned by some friends. One of the guys took the truck for a run in the hills a short way then brought it back where it could go on a lift. It was a slow day and some of the other mechanics came around to see and smell what they could.

Everybody was able to smell something of the hot rubber smell. There were some bizarre suggestions from guys that only half listen to what is being said and just to humor them I let them look to see if there was some roadkill stuck to the pipes. I wasn't sure how baked on skunk, or even horse manure would smell like rubber but it didn't hurt to let them look and sniff around. Incidentally, my wife doesn't always bother to dodge piles of road-apples left behind the Amish buggies and roasting horse manure has a very distinct stink from her Subaru, not at all like hot rubber. A couple of guys that can't tell the difference between hot brake pads and rubber or burned oil checked all sorts of things.

The end result was that we isolated the smell as coming from the right side rear of the engine compartment. We found no hoses or wires near any of the exhaust components. No broken motor mounts which I would expect to hear and feel if the engine was lurching away from the frame. In total there were 5 mechanics plus myself looking the truck over, shining lights into small spaces, handling parts to see if there were any unexpected heat sources and we found exactly nothing.

Over the last few weeks the smell seems to have dissipated. I have even been hauling a loaded trailer up hills in the area. I've noticed no new issues with the truck so I can only hope that what was burning was something it didn't need anyway.

Some things about these trucks seem to be destined to remain mysteries.

 

Any fresh roadwork in your parts? I've had chunks of asphalt get stuck and offgas for quite a while.