car has bad smell when I run it coming from under the hood

When I got our of my car this morning I smelt something coming from my car that smelled like something I can't describe. Now my car needs an oil change once ever 3000 miles and it's only 1000 over that now. There's no smoke coming from my car. And just Friday the ac won't blow anymore out of the front vents. The dash ac is fine. I wonder if they r related. Pls help

My car has 97160 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
For this diagnosis it would’ve been helpful if the smell was described in more detail to help you with the problem. For example, the smell of a dead animal versus the smell of burnt oil. If you cannot describe it then I suggest having a mechanic check the car out in person to see what the problem is.

There are a number of things that can be at fault here and without assessing this issue physically I can only speculate. It’s possible that you’ve got mice in the car’s interior and in the A/C system. They tend to chew on wires and cause all sorts of problems. Have the vehicle inspected by a qualified technician who can diagnose the smell in person and make the appropriate repairs.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

If Your Car Smells Like Acrid Smoke Or Burning Oil

If you notice the smell not long after an oil change, the leak might be caused by a loose drain plug or filter that wasn`t properly attached—or an oil cap that wasn`t screwed on tightly enough.

A burning rubber smell

If your car smells like burning rubber, turn off the engine and check under the hood to see if anything looks out of place. Chances are that the smell results from a belt or other part slipping and rubbing against the hot engine. If you can`t identify the problem, take your car to a mechanic.

Fumes/Exhaust Smell

If you notice fume-like smells while driving, particularly when you`re idling or driving slowly, pull over immediately and exit the car. The smell of fumes could indicate a leak in the exhaust, meaning dangerous levels of carbon monoxide could be entering the cabin.

Over time, engines can develop small oil leaks that would otherwise go undetected. However, if the oil leak forms somewhere high in the engine, and the oil drips down onto a hot component like the exhaust pipe and burn there, you`ll detect an unpleasant smouldering smell in the cabin.
Boil a vinegar and water solution.

Bring 1 cup of water and 1 tablespoon of vinegar to a boil in a small saucepan. Let it simmer for a few minutes. Some people add bay leaves, fresh rosemary, vanilla extract, lemon halves or peels, or cinnamon sticks to cut down the vinegar-smell (and add a pleasant natural odor).

Generally speaking, burnt oil will have a thick, acrid odor. Its unpleasantness will stand out during your drive, and more often than not, you won`t be able to overlook its presence. When this happens, you should safely pull over to examine your engine and check for the cause of the foul smell.
Failing Catalytic Converter (Sulfur Smell)

Over time, the catalytic converter can become overheated, contaminated with gasoline in the exhaust or simply wear out. When this happens, you`re likely to notice a rotten egg, sulphurous smell coming from the exhaust.

5 Common areas that can cause a burning smell from your car: 1) the clutch – may result from riding the clutch or needing a replacement, 2) the brakes – can occur from heavy break usage or riding the brakes, 3) an electrical short, 4) the heater – may result from debris in the system or from a bad motor, or 5) burning …
Using a deodorant may help keep your running clothes fresh in some situations. But it may depend on your body and the type of product you buy. Since odor is produced when bacteria come in contact with sweat, you`ll want to buy a deodorant that also helps to reduce sweating6. These are called antiperspirants.
If your oil smells bitter, soapy, or its smell reminds you of chemicals, it`s most likely rancid. If smell alone isn`t enough to tell if the oil is rancid, take a small sip. A harsh, bitter taste is another sure sign of rancidity.
Clogged PCV Valve

When the PCV valve becomes clogged, it can cause oil to be pushed out of the engine and onto hot engine components, creating a burning oil smell.

The gasket is probably the most common cause of oil leaks, especially in older vehicles or vehicles that are used frequently & have a high number of miles. The gasket is a seal that joins the head two metal parts of the engine, such as the between the block and the head(s) as well as the engine block and the oil pan.
Damaged O2 Sensor

If one (or more) of the oxygen sensors in your car is damaged, your engine may be using too much fuel and not enough air. This could also cause the exhaust to smell like sulfur or rotten eggs, so the presence of this smell alone isn`t enough to determine what the underlying problem is.

You must know there are three things that can cause your car to have this offensive smell. You can have a broken catalytic converter, your fuel pressure sensor may be failing or you may have a fuel filter that is worn out, and you may have old transmission fluid.
A Bad Catalytic Converter Can Burn Through Overtime

If you have to deal with a fully plugged catalytic, avoid driving your car. If you notice smog coming from your car, it is best to seek professional help immediately.

Once the new oil enters the engine and starts removing soot and varnish deposits from the valves and cylinders, it may lead to using (burning) more oil and smoke emitting from the vehicle.
Running the Engine

The oil burns out during the engine`s operation in a matter of minutes.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Soap smell coming out of car after cabin change. Changed filter the the smell is still coming. What to do about this strong smell?
ANSWER : Hi There,
As you know, your car has a cabin filter that serves to filter the air that is introduced to the cabin inside the vehicle. The best way to remove your cars interior ac odor is to use a cleaner that uses enzymes. Enzymes in cleaners kill odors at the source and completely kill the smelly substance material and therefore stopping the a bad smell. To get rid of the smell, try the following: First turn on the ac to full, make sure the “recirculate” button is not on, spray a large amount of cleaner with odor killing enzymes into the EXTERIOR air intakes that are located just below the windshield wipers, let the car run for about 10 minutes with the ac on, after 10 minutes turn off ac and spray the cleaner into the ac vents on the INSIDE of your car. After doing all this, let the car sit for 20 minutes turned off and windows rolled up. Then repeat if the smell is still in the car. By doing this you are killing the bacteria or mold in the car ac vent ducts and also the evaporator mold that may be present.

car has bad smell when I run it coming from under the hood
ANSWER : For this diagnosis it would’ve been helpful if the smell was described in more detail to help you with the problem. For example, the smell of a dead animal versus the smell of burnt oil. If you cannot describe it then I suggest having a mechanic check the car out in person to see what the problem is.

There are a number of things that can be at fault here and without assessing this issue physically I can only speculate. It’s possible that you’ve got mice in the car’s interior and in the A/C system. They tend to chew on wires and cause all sorts of problems. Have the vehicle inspected by a qualified technician who can diagnose the smell in person and make the appropriate repairs.

When I turn on my AC the radiator fans do not turn on. The fans do come on when the car warms up so I know they are working and the fuses are good. The AC compressor does come on and the air blows ice cold when the car is moving. Car is a 2006 Chrysler Sebring Sedan 2.7l v6.
ANSWER : The control circuit for the fans needs to be checked. For example, there is usually a condenser fan relay in the A/C electrical controls. There could be a fault with that relay and/or wiring problems, perhaps even just a loose connection, blown or loose fuse, and so forth. To resolve something like this, the recommended service is an electrical component diagnostic. If you request that diagnostic service, the responding certified mechanic will get the problem pinpointed and resolved. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Replaced alternator on car 2 times each time shows it’s charging 14v let car run for a little bit then test drive and car voltage
ANSWER : There are reports that the replacement alternators will not communicate with the engine computer and will not charge correctly. I recommend using only the manufacturer approved replacement part. It can be new or remanufactured but approved for use in the vehicle. Some lower cost alternators on the aftermarket will have charging problems since they will not communicate with the ECM on the vehicle and will stop charging.

Will a bad battery cause my car to shut off and my EPS light to come on? What would cause it to come on?
ANSWER : Hi there. This is a serious battery problem if the battery is now swollen and has no power. There has been an obviously internal fault. This will cause the vehicle to power down and the EPS light to come on as well. The EPS light is the warning indicator for the electric power steering. I strongly suggest having a qualified technician do a diagnostic inspection to determine the root cause of the battery behavior and if there has been any compromise to the other electrical systems. It may only be a failed battery. If you’d like to have this checked, YourMechanic has several technicians available that can assist you with an electrical inspection and can replace your battery as needed.

Charging warning light comes on when i turn the key and try to start the car and the car want start but when someone tried to give
ANSWER : Hi there:

If you recently replaced your battery, the issue may be caused by a malfunctioning alternator or other electrical component that comprises the charging system on your Nissan Sentra. The best way to find out which item specifically is faulty, is to have a professional mobile mechanic complete a car is hard to start inspection. This will allow the mechanic to determine the precise source of what’s going on with your Sentra and recommend or complete the right repairs.

Power steering loss, no belts are turning but the car is running fine. I also have a soft pedal. Whats wrong with my car?
ANSWER : I have only seen this situation once in my 30+ years and it turned out to be a broken crankshaft pulley. Belts are driven by the engine. The crankshaft pulley spins the belts, which in turn spin the air conditioner compressor, power steering and water pumps, and the alternator. The vehicle should be towed to your local repair shop and not driven. Without the water pump spinning to circulate the coolant, the engine will quickly overheat and result in more extensive damage.

Heard a pop under hood while driving and my car suddenly started running hot.
ANSWER : The first thing I would do is to open the hood and do a visual inspection. Look for a broken drive belt, or something else broken like a pulley or presence of fluid leaks. The loud pop and overheating symptoms could also mean that you have a blown head gasket. I recommend having the vehicle inspected as soon as possible to determine the cause of the overheating issue and pinpoint the fixes that are needed to prevent further damage.