I recently purchased a 2005 automatic Hyundai Accent. A few weeks after purchasing it, I started noticing an alarming burning, rubber-like, smell coming from under my hood when driving up steep grades. The smell is more pronounced when I have the vents on or the window down, but I can smell it with both of these closed as well. It does not seem to matter whether I have been driving for 10 minutes or several hours, hot or cold, day or night. So far, the smell has only occurred when going uphill, several minutes after the road flattening out or heading downhill, the smell subsides.
So far, I have taken it to two mechanics who have run through all of the possibilities that they can think of. Unfortunately, neither one of them have been able to replicate the smell during test drives, even when driving uphill. (To my credit, several of my friends have been in the car with me and smelled this smell, which they described as “burning rubber.”) Both mechanics said that things looked great under the hood and that they were stumped.
Theories that the mechanics explored and decided weren’t the problem included:
leaks (oil/coolant)
broken fan motor (which the other mechanic credited as being a bogus theory)
drive belts need to be replaced
brakes (which wouldn’t explain the uphill timing of the problem)
I am trying to decide whether to keep the car or not. The smell is very alarming and I experience it three to four times per day on my commute. Even with the reassurance of the mechanics, I do not have any piece of mind!
Any theories or similar experiences that you can share would be greatly appreciated.
I am going to suggest that you have oil dripping on the exhaust system–probably the exhaust manifold. The oil is probably dripping when the engine is tilted at an angle when you are going uphill. Hot oil does smell like burning rubber. Some years back, I had a colleague who complained that her car smelled like burning rubber. The car was an early 1970s Oldsmobile. I went out with her and had her start the car. I watched the engine. As the engine warmed up, I could see the smoke rise off the exhaust manifold and the smoke definitely had a burning rubber smell. In her case, the problem was a leaking valve cover gasket–a very inexpensive repair. You might have a mechanic raise the front of the car when the car is at normal operating temperature and the engine is running . This might pinpoint the problem.
Got any weird electrical issues in the vehicle? I am hoping that you dont have something arcing out and melting the rubber insulation or something rubber being melted due to overheating/arcing electrical wires…that get displaced going uphill and start melting something…
Aside from something similar happening under the hood and hitting the exhaust manifold I cant think of anything else causing this. Take a look under the hood to see if there is anything melted…made of rubber…near your exhaust manifold…or same thing under the car near the catalytic converter or the first half of your exhaust starting at the front of the car and ending about midway. Seems like something is moving/displaced when the car is tilted nose up…and hitting something hot enuf to melt it…OR something electrical is happening with the car nose up and arcing out…but methinks you would see immediate electrical issues/gremlins… More likely I would be looking for rubber melting scenarios in relation to your exhaust…either under hood or near cat converter. That’s all I can come up with …sorry.
My first thought was also an oil leak onto something hot, as Triedaq says. It doesn’t take much oil to make a strong smell. On a calm day, can you get the car warmed up, park on a steep hill, open the hood, and watch for smoke? When my wife’s car had a valve cover gasket leak, we were able to see some smoke by doing this.
Has your oil level been dropping much each time you check it?
I’m incllined to agree with the oil theory. It may be happening going up steep hills because the loaded engine is pressurizing the crankcase more than normal. That’ll force oil past worn main seals (the ones on the crankshaft ends). With the car at an angle the oil could be running down onto the exhaust system.
Has the car been using oil?
Have you put the car on ramps and checked underneath?
Did the mechanic(s) check the PCV valve? A stuck valve will increase crankcase pressures.
Did one of the mechanics suggest a UV sensitive dye oil additive to find any possible leak (using a “black light”)?