Burning Oil Smell Through Vents – Possible Causes and Fixes

Burning oil smell through vents can be frustrating to many drivers, and it could be caused by engine leaks, exhaust gasket leaks or others. Having burnt oil fumes and exhaust gasses escaping into your car through the ventilation intakes can affect your driving.

Therefore, it is essential to determine the problem and rectify it quickly. This article will guide you through the most common reasons for burning oil smell through vents and how to fix the issue.

What Are the Causes of Burning Oil Smell Through Your Car Vents?

The causes of burning oil smell through your car vents are mainly related to engine oil leaks. The leaked oil may spill on hot surfaces, causing it to burn and leave a stench in your engine compartment. However, there are many other probable causes of this issue.

Valve Cover Gasket Leaks

The valve cover gasket plays a crucial role in sealing the oil within the engine and protecting it from external elements. However, high mileage can cause wear and tear, leading to oil escape and burnt smells in the cabin, which is dangerous and harmful to the engine’s components. These leaks are challenging to detect as the oil dissipates quickly.

Engine design can lead to more oil leaks from the back of longitudinally placed engines, making diagnosis difficult. The problem is often caused by loosened or broken valve cover nuts or a damaged valve cover gasket due to the car’s age. Replacing both the bolts and gasket is recommended to prevent further leaks.

Exhaust System Leaks

Exhaust leaks in the engine compartment can lead to a burning odor in the cabin, often mistaken for a burned oil smell. These leaks occur near the exhaust manifold, pipe or catalytic converter and can allow exhaust gasses to enter the car. Significant leaks may alter the engine’s tone, producing a whistling or buzzing sound.

PCV Valve Leaks

The PCV valve is responsible for regulating positive crankcase ventilation. A faulty PCV valve can trap high pressure in the valve cover, leading to oil leaks in the engine compartment. You may smell burning oil if the PCV valve is faulty.

The system is designed to release pressure from the engine crankcase and prevent oil leaks. Consequently, you may perceive a burning smell when oil drips onto a heated surface. Checking the PCV valve and its vacuum hoses is crucial.

Low Levels of Engine Oil

Maintaining the proper oil level in your engine is crucial to prevent overheating and damage. The oil level should be between the high and low marks on the dipstick. Low oil levels may lead to engine overheating and engine smell through car vents.

Manufacturers typically recommend changing the engine oil every 3,000 miles or every three months. Regularly following this schedule ensures proper maintenance of the vehicle. Neglecting to check the oil level before driving can lead to severe consequences if a problem arises with the car.

Improperly Done Oil Change

Improper oil changes can lead to oil spilling into the exhaust system and other components. The oil spilled on hot surfaces evaporates when the engine warms up, causing a distinct oil smell. If no other leaks exist, the oil will eventually burn up, and the odor will dissipate within a few days.

Some common reasons for oil leaks after an improper oil change is the incomplete removal of the old gasket or improper installation of the new gasket. Therefore, having your oil changed at a reputable workshop is essential.

Faulty Catalytic Converter

Clogged catalytic converters can result in a burning oil smell through vents. Its primary function is to absorb fuel to prevent harmful emissions in the environment.

However, the converter’s efficiency can be compromised by the buildup of carbon or other materials, leading to incomplete absorption. Unabsorbed fuel then burns, causing the car to emit a burning oil smell.

Defective Engine Parts

As car engine parts wear out over time, their ability to seal oil in the engine diminishes, leading to oil leaks and a burning oil smell in the cabin. When suspecting worn-out engine parts, you should have a mechanic inspect the car and replace the necessary components.

Piston rings play a critical role in the compression system. It seals the combustion chamber to prevent oil from entering the exhaust and exhaust gasses from leaking back into the cylinder during driving. Damaged piston rings can cause a burning oil smell if not addressed promptly.

Main and rod bearings are common culprits of engine oil leaks. Main bearings support the crankshaft’s weight and endure constant pressure as it rotates. Rod bearings support the connecting rods. Thus, wear and tear is inevitable over time, necessitating their replacement.

How Can You Fix a Burning Oil Smell Through Your Car Vents?

You can fix a burning oil smell through your car vents by determining the cause of the issue. Then go ahead to fix any leaks discovered or replace components that may be causing the problem. An air freshener can temporarily make the smell disappear, but won’t provide a lasting solution.

Find Out the Causes of the Issue

Identifying the source of a burning smell in a vehicle requires understanding the possible causes. It could be an engine oil leak reaching the exhaust or severe wear in oil rings or gaskets. Determining the faulty component can be challenging due to the different viscosity oils used for the engine, brakes, and transmission.

A complete inspection by a professional technician or auto repair shop is advisable. A method similar to diagnosing a tire puncture can be used for a DIY inspection of exhaust leaks. Spray soapy liquid near the exhaust manifold and cold pipes of the cooled engine. Bubbles forming will indicate the location of the leak.

To examine the PCV valve, it can be removed from the valve cover. A functioning PCV valve should generate a significant vacuum when touched with a fingertip while the engine is running.

Don’t Ignore Any Signs

Ignoring early signs of problems in a vehicle can cause more serious issues in the later. Warning signs include gears not shifting correctly, unusual noises during gear changes, the engine running hotter than usual, and a dramatic drop in oil level without any apparent leaks. Delayed brake functioning is also a concerning issue.

These seemingly minor problems can escalate over time, resulting in a burning oil smell. Neglecting these signs might damage gear shafts, pistons and rings, causing leaking oil and the smell of burning oil. It is crucial to pay attention to minor symptoms and address them promptly to prevent further issues.

Fix Any Exhaust System Leak

Inspect your car’s muffler and tailpipe for any visible cracks or holes to check for an exhaust leak. If you notice such damage, then your car needs a repair job. Start by tightening all of the fasteners. If this does not resolve the issue, consider replacing damaged parts with newer ones from an auto parts store or mechanic shop.

Replace the PCV Valve

To fix the issue of a leaking PCV valve and eliminate the strong odor, the best solution is to replace the PCV valve with an updated version that performs better. To do this, remove the car’s valve cover and disconnect the old PCV valve from its connection point inside the engine. Then, install the new PCV valve by screwing it back into place using an adjustable wrench or a ratchet set.

Repair or Replace Faulty Catalytic Converter

If you’ve been detecting a burning oil smell through the AC vents, it indicates a potential issue with a broken catalytic converter. A damaged catalytic converter can cause internal harm to other car parts and emit toxic fumes through the vents.

To replace a broken catalytic converter, start by removing all four wheels to access the vehicle’s underside. Locate the catalytic converter on the engine (typically near or under one of two exhaust pipes), remove the bolts holding it in place, and then carefully install the new unit using new bolts.

Replace Defective Piston Rings

An oil-burning problem in a vehicle may be caused by worn piston rings, which allow more oil to pass into the cylinder and result in poor combustion. Remove the spark plugs and inspect the cylinders for visible carbon buildup to check if the piston rings need replacement.

If such buildup is present, it suggests damage to the cylinder walls from excessive blow-by gases escaping past seals or gaskets before being burned in combustion.

If worn piston rings are found to be cracked or broken, they should be replaced to resolve the issue. After replacing the piston rings, run another series of tests on the vehicle for about 10 minutes to ensure proper functioning.

FAQs

Should You Continue Driving if Your Car Smells Like Burning Oil?

No, you should not continue driving if your car smells like burning oil, especially if the burning smell is coming through your air vents. Likewise, you should stop driving if the smell is from a heating system problem. Wait for your mechanic to come and fix the problem.

Why Does Your Car Smell Like Burning Oil During Idling?

Your car smells like burning oil during idling because of oil leaks. This may present as a noticeable thick burning oil, mostly due to oil dripping on hot engine surfaces. It could also mean that your car is overheating, and you should check it as quickly as possible.

Can a Burning Smell Occur Due to Too Much Engine Oil?

Yes, a burning smell can occur due to too much engine oil. Overfilling of the oil may cause overflowing, thus leading to a leak. Oil leaking on heating engine components will produce an acrid burning smell. Therefore, you must ensure you carry out the oil change properly.

Conclusion

A burning oil smell through vents often indicates oil or exhaust leaks, and you should stop your car and fix the issue immediately.

Here are the important points we discussed in this article:

• The causes of the burning oil smell through your car vents are mainly engine oil leaks and exhaust system leaks.
• Other causes include PCV valve leaks, low engine oil levels, a poorly done oil change, a faulty catalytic converter or worn-out engine parts.
• The solutions to a burning oil smell start by determining the root cause of the problem and not overlooking even the slightest signs.
• Then repair or replace any faulty component that may be causing this problem, including the PCV valve, piston rings, catalytic converter, etc.

Remember that you should never ignore a burning oil smell through your vents. Therefore, you should check and fix the underlying issue or get your vehicle to a qualified auto workshop for proper inspection.