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Tips on Troubleshooting Smells That Come From the Car Engine

Troubleshooting Smells That Come From the Car Engine.

Car smells with no apparent origin often mean trouble and should never be ignored. Oftentimes, this strange odor comes from the engine. There are some issues you can troubleshoot on your own but there are other issues that need the immediate attention of a professional. Here we give you a list of common car smells that come from the engine with tips on what action you should take to address the problem. 

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Rotten Egg/Sulfur-like Odor


If your car starts smelling like rotten eggs, chances are there’s an imbalance in your engine’s fuel to air ratio. When you have fuel-injection issues, the unburned fuel can plug the catalytic convertor, and the exhaust gets trapped or clogged so your car won’t run. 


Course of Action: This issue cannot be addressed on your own. When this happens you should have a mechanic check your car immediately. If you are able to catch the issue early enough, you might be able to save the catalytic converter.


Moldy or Musty Smell


The A/C runs by pulling moisture out of the air. The water that is drawn out then goes into a box at the back of the dashboard which has a drain. Sometimes, papers or leaves can get into that box and clog the drain. When this happens, the water becomes stagnant and will get moldy. This is an expensive problem to fix. To make it worse, the water usually gets out of the box and goes onto your carpets and floor-mats. Molds can also build up in your duct system and to prevent this from happening you should regularly run your air conditioning system.


Course of Action: If your car starts to smell musty or moldy, have it checked out immediately. To prevent moisture from building up, make sure to run your A/C monthly for a few minutes even if you do not need to cool off. Doing this will also help in lubricating oil seals and bearings in the compressor which will help it last longer. 


But if the car still smells moldy after your A/C has been fixed then the problem can be caused by another issue. One of the common causes is a damp carpet. The floor can absorb and store moisture from an open window, the snow that gets in the car or a malfunctioning climate system. One way to fix this issue is to steam clean your floor and treat it with a carpet cleaner. You can use the air conditioner on recirculation when driving to dry out the interior of the car. You can also park in the sun with the doors open during a hot and low-humidity day. 


Sweet or Fruity Scent


A maple syrup scent coming from your engine is most likely a coolant escaping from the cooling system. This is an indication that you have a leak that could lead to a much bigger problem like overheating your car. 


Course of Action: You would have to check if your cooler has any cracks in it. The cracks may be small but they can leave huge hazards and repair costs. You should have your vehicle towed to the nearest repair center as driving your car with a coolant leaking can damage the engine.


Acrid Smoke or Burning Oil Smell


If your car starts smelling like burning oil, then you probably have an oil leak. This condition is dangerous. It could cause fire if it hits the exhaust. If it started to smell not long after you have your oil changed, a loose drain plug or an improperly attached filter might be the cause of the leak. It could also be that the oil cap was not screwed properly or not tightly enough. Also, an oil leak from a seal or bad gasket can lead to issues like oil dripping on the crankshaft seal or the timing belt. These are definitely not something to disregard as they could really damage your engine.


Course of Action: When this happens, you should stop the engine and jack the car up. Check the oil dipstick. It could be that your running out of oil or the engine is overheating and your temperature gauge may be malfunctioning. If the issue is neither the two then check around the engine for oil leaking onto the exhaust manifold or the engine block. If this is not the case, check your transmission fluid dipstick. A broken vacuum modulator can sometimes siphon the fluid out of the transmission and feed it to your car’s engine where it gets burned. Having a low transmission fluid can also burn in the transmission since the gears are not lubricated enough then they are getting very hot. Do not continue to drive when there is oil leaking for it may cause bigger problems. When there’s an oil leakage, you need to have it fixed immediately. 


Burnt Carpet Odor


When going down a steep hill and having your foot on the brake for a longer period, even just lightly, and you start smelling a burnt carpet odor your brake pads or rotors are overheating. This condition can lead to premature brake wear or in more serious cases, a brake failure. This odor can also be an indication that your brake pads are too thin or can also be caused by dragging or sticking brake calipers. If the smell does not go away and you have not been driving in a way that applies pressure on the brakes, then you better have your brakes checked immediately. Keep in mind that once you have your brake pads replaced, it is normal for them to give off a scent for the first two hundred miles. 


Course of Action: When going down steep hills, make sure you pump the brakes on and off. The piston caliper should also be in a position where it can be functioning properly. 


Exhaust or Fumes Smell


An exhaust leak that makes its way into the inside of the car can quickly increase the amount of carbon monoxide to hazardous levels. 


Course of Action: When this happens, roll your windows down immediately then pull over to the side of the road as soon as possible. Turn your engine off and have your vehicle towed to a repair center. 


Burnt Rubber Scent


This scent may be caused by a hose from the cooling or power steering that is rubbing on a belt and has begun to melt. It could also be a clutch problem. The burnt rubber smell is caused whenever you shift gears and the clutch’s face burns off when it slips. The surface of the clutch is a type of paper mesh so that’s why it smells rubbery. To prevent this from happening, you should use the clutch properly. Rule of thumb: Do not ride the clutch. If you ride your clutch frequently you’ll end up replacing it. 


Course of Action: Let your car cool down first. When it’s cool to touch, open the hood and check your belts and hoses. Rescue the hose before it melts through. You would need to replace the faulty belt. Make sure to check your belt every 6 months. If the smell does not go away, take your car in to be inspected. If the clutch is the problem, you need to replace the worn clutch. 


Burning Plastic Smell


A short circuit in the wiring might be the culprit. When the plastic insulation of the wires worn down or chewed off by an animal that has made its way into the engine, the wires that have been exposed can rub together and cause a short. This could result in a fire. Other kinds of shorts can burn or melt the plastic away directly. But the smell could only be caused by a plastic bag that has landed on the exhaust and got melted due to the heat. 


If the above mentioned issues are not the cause, then it could be your heater. If your heater starts smelling that something is burning then it could be that there is dust accumulation in the system especially if you haven’t been using your heater for a long time. However if the burning smell still persists even after regularly using the heater, then you may have some debris clogging the vent. It could also be that the heater is broken and the antifreeze is finding its way into the vents. The worst part is that most likely your heater has melted to cause this burning smell. If the smell becomes stronger and the vent is not clogged, have your car checked by a mechanic right away. 


Course of Action: Move to the side of the road safely. If the issue is some plastic on the exhaust, do not grab it because chances are it is very hot. If the smell comes from the heater, have your air filters cleaned or replaced if needed. Use antibacterial products for the vents. But if you can’t identify where the smell is coming from, or it continues to smell then have a mechanic check your car for diagnosis and repair. 


Gas Odor


A gas smell inside your car could be caused by a gas leaking in the engine or close to the exhaust (such as the fuel line). This is one of the most hazardous smells as a gas leak could start a fire when the raw fuel gets into contact with the rotating engine parts or the hot exhaust system. If your car is from the 1970s or earlier, a lingering gas smell after turning off the engine might be normal but if it is strong you still have to get it checked out.


Course of Action: Move to the side of the road safely and turn off the engine right away. Have your car towed to the shop. If you just had difficulty starting your vehicle, there is a chance that the car may be flooded. What you have to do is wait a few minutes and try again. If the odor comes from under your hood, check the fuel injection system or carburetor to make sure that there is no leaking fuel. You should also check the fuel pump (if not hidden inside the fuel tank). You will see  a clean streak across the fuel pump if there is leaking gasoline. Also check all visible fuel lines and hoses leading to the fuel tank. If they have worn down or are disconnected, you will smell fuel vapors but you won’t see any leaks. You can take a look under the vehicle after it has been parked overnight may help. However, fuel evaporates fast so you might only see stains instead of wet spots. 


There are many reasons you might want to do the troubleshooting on your own. But it is important to remember that when there is a burning smell from your car, it can be dangerous. The best option is still to take it to an auto repair shop immediately. 


If your car stinks and you have determined that it is not caused by a mechanical issue, you probably want to make it smell better. The first thing you should do is to make sure you remove any spilled food or drink or any food you have left inside the car. For stubborn stains on your carpet, one hack is to sprinkle it with baking soda. Leave it on for a few hours, and once it sets in you can vacuum it up. If you have already gotten rid of everything that could cause the smell and it still smells bad, you can leave a chunk of grilling charcoal in your car for a couple of days. The charcoal will absorb a lot of the ambient odor. If it still stinks, then you better begin shampooing the interior of your car on a regular basis. Remove the floor mats, mix water and detergent, and scrub the mats. And if it still fails, then you properly need to use upholstery shampoos. You can get them from auto shops. But if you have the budget then you can take the vehicle in to be cleaned. 

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