Oil Coming Out of the Exhaust: Causes, Fixes and More

The sight of oil spewing from a car’s exhaust is not only unusual but also deeply concerning. This alarming occurrence hints at underlying problems within the vehicle’s engine and demands immediate attention. That said, we have penned why one would notice oil coming out of the exhaust system. We have also provided solutions to cater to these problems for prompt repair.

COMMON CAUSES OF OIL COMING OUT OF THE EXHAUST

A car exhaust system is crucial for the proper functioning of the vehicle since it exhausts harmful fumes from the cabin and engine. However, over time, it may be subjected to different issues.

One might notice water coming out from the exhaust or smoke in unusual colours. Similarly, oil coming out of the exhaust is another underlying issue in the vehicle. Let’s go through the potential causes of oil coming out of the exhaust and how to prevent them.

FAILED VALVE SEALS

The function of an engine valve involves valve seals which prevent oil to enter the combustion chamber. If they fail, oil can leak into the combustion chamber and be burned, which will cause engine oil to come out of the exhaust.

causes of oil coming out of exhaust due to bad valve seals — Failed valve seals cause the oil to expel from the car exhaust

FAULTY PCV SYSTEM

The Positive Crankcase Ventilation (PCV) system is responsible for redirecting blow-by gases from the crankcase back into the intake manifold to be burned. If the PCV valve or related components are faulty, excessive pressure can build up in the crankcase.

This causes the oil to be forced into the combustion chamber and subsequently out of the exhaust. Apart from these symptoms, one may also notice oil-covered spark plugs.

WORN PISTON AND PISTON RINGS

Piston rings are a vital part of the combustion chamber which prevents the oil from entering it. However, if one or more piston rings become broken or damaged, the oil leaks into the combustion chamber and expels through the exhaust. Also, oil burns with the air-fuel mixture and creates a blue smoke. It impacts the efficiency of the engine and is also a major fire hazard.

causes and symptoms of oil coming out of exhaust such as bad pistons — When piston rings become damaged, the oil leaks out of the exhaust and burns with the air-fuel mixture

CRACKED CYLINDER BLOCK OR HEAD

Located on the top of the car engine, the engine cylinder heads are a crucial part of the engine block. Although they are responsible for mixing gas and air, cracked engine cylinder heads quickly deteriorate a car’s working. Common symptoms of such damage include visible smoke from the engine, misfiring or oil coming out of the exhaust.

BLOWN HEAD GASKET

An engine head gasket is responsible for keeping the different car fluids separate from one another. However, a blown head gasket causes oil and coolant to mix. When this happens, the oil is burnt and expelled through the exhaust system. One may also notice other symptoms like white smoke, overheating, or coolant loss.

ISSUES IN TURBOCHARGER

The main purpose of a turbocharger is to boost the engine’s output power. However, in case of any rupture in this component, a vehicle’s functioning is compromised.

A failing turbocharger leads to the engine oil coming out of the exhaust along with sluggish acceleration, a check engine light or excessive consumption of fuel. It mainly malfunctions due to damaged bearings, worn seals or excessive oil pressure.

FIXES FOR OIL COMING OUT OF THE EXHAUST

After going through the potential causes of oil coming out of the exhaust, here are some practical ways to fix this issue. It is necessary to address such an issue at the earliest to avoid any further damage and seek professional assistance. One may also opt for dubizzle inspection services for cars to inspect such problems. These fixes are as follows.

simple fixes when oil comes from exhaust system of a car — Such issue must be inspected promptly to avoid further damage

OPT FOR A LEAK-DOWN TEST

Opting for a leak-down test helps to diagnose the underlying problem. One may make this test using professional equipment in the following manner:

Ensure the engine is turned off and cool.
Remove the spark plugs from all cylinders.
Set the piston of the cylinder you want to test to the top dead centre (TDC).
Attach a leak-down tester to the spark plug hole of the cylinder.
Apply compressed air to the tester.
Listen for any hissing sounds indicating air leakage and observe the pressure gauge on the tester.
Compare the pressure readings and listen for leaks at the exhaust, intake, or crankcase.
Repeat the process for other cylinders, setting them to TDC one at a time.
Analyze the results for variations in leakage percentage.
The point through which the air is escaping is the source of the issue.

CLEAN PCV VALVE

Among the fixes for oil coming out of the exhaust, cleaning the PCV valve is an easy option. It involves the following steps:

Remove the PCV valve.
Inspect the valve for any visible dirt, debris, or clogs. If necessary, use a small brush or compressed air to remove the buildup gently.
Soak the valve in a container filled with a mild solvent or cleaner. Allow it to soak for a few minutes to loosen any stubborn residue.
Use the brush or compressed air again to clean the valve thoroughly, ensuring all obstructions are removed.
Rinse the valve with clean solvent or water to remove any remaining solvent or debris.
Shake off excess liquid and allow the valve to air dry completely before reinstallation.
Check the hoses for any damage.
Reinstall the PCV valve.
If it doesn’t function after the above-mentioned steps, a new PCV valve is required.

oil coming out of exhaust Fixes such as cleaning the PCV valve — If the PCV valve is clogged, it must be removed and cleaned thoroughly

REMOVE OIL CAP

Carefully remove the oil cap while the engine is running to prevent any splashes. If a little amount of air blows from the filler cap, then the motor is running normally. On the other hand, if the air blows out excessively or one notices a fuel smell, it is a symptom of a clogged PCV valve which must be cleaned or even replaced.

CHECK TURBOCHARGER

A car turbocharger failure occurs due to several reasons which hinder the car’s efficiency. However, one may check for the root cause of this failure through different methods. Visually inspect the exhaust and intake impeller of the turbocharger.

After that, remove the intercooler hose to check the oil level. External damage on either of the impellers is a sign of a bad turbocharger bearing which causes an oil leak.

a failed turbocharger can cause oil to come out of the exhaust system — A failed turbocharger must be inspected by checking for external damage on the impellers

All in all, these were the main causes of oil coming out of the exhaust and how it can be prevented. Moreover, such car problems indicate a malfunction which must be looked into properly. Therefore, if you are facing such car issues time and again, it is better to opt for a better ride. To do so, sift through these used cars for sale in the UAE and find a car that best fits your budget and preferences.

Keep reading dubizzle’s auto blog for more on car problems, repairs and maintenance tips.

Oil Coming Out of the Exhaust: Causes & Fixes