Oil Leak From Intake Manifold Gasket (Causes and Fixing)

Engine problems are some of the most complex and expensive challenges to fix in a car. No wonder vehicle manufacturers and professional auto technicians recommend swiftly responding to any suspicious malfunction.

An oil leak from intake manifold gasket is a malfunction that requires a swift response to avoid unnecessary escalation of the problem. If your vehicle is currently suffering from this issue, do not fret.

This article reveals the causes, symptoms, and possible solutions to the problem. Carefully follow this guide to the latter.

oil leak from intake manifold

Oil Leak From Intake Manifold Gasket – Causes

Sometimes, having a very small amount of oil around the engine compartment is normal. However, if the area becomes flooded with fluid, it is a sign that you have a problem to deal with ASAP.

If this is the case for your car’s intake manifold gasket, the following issues may be responsible for the oil leak.

Worn piston rings

Worn Piston Ring

The piston rings are designed to serve as a seal to the cylinders in the motor. Unfortunately, these components are prone to wear out over time.

Meanwhile, the worn piston rings could give access to oil leakage, which may end up leaking into the manifold. When this happens, the oil leakage can cause the vehicle’s engine to vibrate and smoke.

Bad PCV valve

The PCV valve is vital as it plays a powerful role in regulating the intake manifold’s vacuum, preventing oil leaks. If this component becomes defective, it will be easy for oil to gain access.

Of course, when the fluid gains access through the intake manifold, you will most likely experience a smoking engine. 

Blocked oil passage

Vehicles are designed with a couple of oil passages that enable the free flow of the liquid from one spot to another until it reaches all the necessary components. Unfortunately, dirt and debris may clog one or more of these channels, obstructing the flow.

When this happens, oil may find its way around the intake manifold gasket of a vehicle. Like a bad PCV, this can also result in smoking from the engine oil cap.

Failed turbocharger

For vehicles designed with a turbocharger, it is possible to experience an oil leak in the intercooler and intake manifold due to a failed turbocharger. The turbocharger failure negatively impacts the obstructed return line or seals, causing oil leakage.

Leaking valve seal

A vehicle’s cylinder head valves are securely held in place by valve seals. However, the valve seals do not last forever.

In other words, when the seals are compromised, oil will easily leak into the intake manifold. Again, like the bad PCV, this can result in a smoking engine. 

What Are The Symptoms Of Oil In The Intake Manifold?

Excessive oil in intake manifold comes with a series of malfunctions that can easily be noticed in a vehicle. If you see the following symptoms, you likely have oil in your car’s intake manifold.

Smoking engine

As stated above, a bad PCV valve, worn piston rings, leaky valve seals, and blocked oil passages will easily trigger engine smoke. This particular symptom ranks as one of the most obvious signs that you have oil inside intake manifold.

However, other vehicle malfunctions can trigger engine smoke apart from oil in the intake manifold. In other words, it is important to carefully diagnose the actual cause of the smoking engine before attempting to fix the problem.

Fouled spark plugs

Oil leak from intake manifold can easily impact the spark plugs, resulting in the components being flooded with the fluid. When this happens, you will experience other symptoms like engine misfire and difficulty starting your car.

Engine misfire

Several vehicle malfunctions, including oil leakage in the intake manifold cause engine misfire. So, if you notice this particular symptom in your car, carefully figure out which faulty component is responsible for the issue. 

Engine power decline

Lastly, if you have oil leaks in your vehicle’s intake manifold, you will most likely experience a decline in the engine power, resulting in poor acceleration, excessive fuel consumption, etc.

Again, these symptoms can also be traced to other malfunctions. So, you must be strategic when attempting to fix the problem. That’s why you should contact a professional auto mechanic to conduct the diagnosis and fix the problem.

How To Fix Oil Leaking From Intake Manifold?

Fixing oil leaks from your car’s intake manifold is pretty straightforward. However, the workload or cost may differ due to the cause of the problem. The following are simple ways regarding how to fix oil in air intake manifold.

Clean/Replace PCV valve

If a bad PCV valve is the cause of oil in the intake manifold, fixing this problem can be relatively easy. Take a moment to get a degreasing agent, an oil catch pan, and a rag. Then, remove your car battery’s negative terminal.

After that, locate the PCV valve somewhere in the valve corner, depending on your type of car. Then, take off the component. Once you get the component off, carefully clean off any oil on the component. Ensure to clean up the part thoroughly.

However, if cleaning up the PCV valve doesn’t restore the component, you may have to replace the part with a new one. This will only cost a few bucks, somewhere around $25.

Clean oil passageway

Cleaning the oil passages will help to rectify the oil leak in your vehicle’s intake manifold if this is the case. However, the task can be very burdensome if you’re not an auto mechanic. The process requires uninstalling various engine parts before accessing the designated area.

Additionally, you will need to drain out the engine oil. After that, you can clean the passageways using wire brushes. Never try to perform this task yourself if you don’t know what you’re doing.

It is advisable to outsource this job to a professional auto technician to handle it, as any inconsistency in the process of cleaning the passages can lead to costly engine damage.

Replace the failed turbocharger

The remedy for a failed turbocharger is to replace the component with a new one. Depending on your car type, replacing a turbocharger can cost around $750 – $1,250. Meanwhile, contact an expert auto technician to fix the component to avoid any complications.

Alternatively, if you discover that the turbocharger is not completely bad, you may want to fix it personally. However, this job is for a confident DIYer who can handle such a task.

Replace the leaking valve seals

If you discover that the oil in the intake manifold is caused by leaking valve seals, replacing the components will help to rectify the problem.

You can choose to do the replacement personally if you’re a DIYer. However, allowing an expert to replace them would be best.

Replace worn piston rings

Lastly, replacing worn piston rings is the costliest as far as oil in the intake manifold is concerned. However, this is due to the cumbersome nature of fixing the components. The cost of replacing the piston rings is estimated at around $1,000 – $5,000.


Like most engine-related vehicle issues, oil leak from intake manifold gasket can degenerate into more severe engine problems. Hence, identifying the issue early enough would be an advantage.

So, you must not take any slight manifestation of the symptoms above lightly until they escalate. Ensure to swiftly respond once you notice engine smoke, fouled spark plugs, engine misfire, and a decline in engine power.

Following the recommended solutions in this article can help you rectify the oil leak from your vehicle’s intake gasket. However, do not attempt to do a job exclusively reserved for the professional to avoid complications.


Mr. Shafiqule Islam is a graduated Mechanical Engineer and has more than 15 years experience of repairing and maintenance of different brand vehicles like Toyota, Mitsubishi, Ford, Mercedes, BMW etc. He is also giving training to Mechanics. He has started writing to share his practical knowledge to Vehicle Owners, Drivers and Mechanics to keep their cars at best fit.

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