Oil in intake manifold: The Causes and How To Fix It

It is not easy to manage engine problems. This is why oil buildup in the intake manifold could cause serious issues. However, there are some problems that aren’t that tricky to deal with.

These are the causes. This guide will help you diagnose and repair oily intake manifolds quickly. 

There are many reasons to take oil in intake

An oily intake manifold could result from a bad PVC or an obstruction in one of the oil passages. You could have a leaky valve seal or an inoperable turbocharger that allows oil to enter the intake manifold. If that’s not the problem, you should also take a look at the piston rings.

It could still be normal if the intake manifold has a small amount of oil. It’s when it’s flooding the intake manifold and causing blue smoke from your exhaust pipe, you should be worried.

1. PVC Valve Faulting

The car’s PVC valve is needed to regulate the vacuum in the intake manifold. If it starts to fail it can allow oil into the intake manifold. The engine will start smoking when this occurs.

This is one of the easiest problems to fix among what’s found on our list. In a moment, we will talk more about this. 

READ MORE: 7 Symptoms of a Bad PCV Valve (& Replacement Cost)

2. Turbocharger Failure

Turbochargers can cause oil leakage in intake manifolds if they fail. Leakage can occur when the turbo stops working.

The intercooler is where most oil goes. However, it’s also possible to see some in the intake. 

3. Oil Passage Clog

The engine has oil passages through which the fluid must freely flow. The manifold could be clogged if oil is not flowing freely through one or more passageways. 

The result will be a smokey engine. Plus, it’s not as simple to repair as the PCV valve. It’s best to keep the passageways clear, so this never becomes a problem. Regular oil changes are essential, as well as maintaining filters. 

4. Leaking valve seal

To secure the valves in the cylinder heads, the valve seals must be installed. Leakage can lead to oil getting into the manifold.

You will need to handle engine smoke if it happens again. Most average at-home mechanics won’t want to handle this repair on their own.

READ MORE: 6 Symptoms of a Bad Valve Seal (& Replacement Cost)

5. Bad Piston Ring

To seal the motor's cylinders, the piston rings also need to be replaced. They can also wear over time.

Oil can leak when this occurs. The oil can leak into the intake manifold causing a smokey engine. 

RELATED: 4 Symptoms of a Bad Piston Ring (& Replacement Cost)

Oily Intake Manifold Symptoms

If oil is found in the intake manifold you'll notice signs that indicate the problem. Here are some of the symptoms that most often indicate engine smoke.

Of course, most of these problems can also occur with other faults, so it’s difficult to determine that these are caused by oil in the intake manifold. You might have low compression or dirty filters.

Only a professional mechanic can diagnose and check the system to be certain. If you don’t have the equipment or skills to perform a diagnosis, take it to a professional mechanic. 

Intake Manifold Repairs Oil

1. Clean/Repair PCV Valve

It is best to check the PCV valve for any problems. This job can be done at home in most cases with very little equipment. It is possible to complete the job at home if you have an oil trap pan and some rags.

Start by disconnecting the negative battery terminal, so there’s no chance of electrical hazards.

The PCV valve is located in the cover. You will find it in the valve cover depending on your vehicle's age. You can remove the valve cover and clean it. You can wipe off any oil on the valve with your degreaser. Also clean the ports and the surrounding area. 

Sometimes, just cleaning the item is all that's needed to make it work again. If that doesn’t work, you might need to replace it. However, the part shouldn’t cost you much more than $25 and you can put it on yourself. If you must pay for labor, there’s no reason to pay more than one hour.

Once everything is finished, clean the intake with your degreaser. Be sure to pay attention to tight spots that might be overlooked. When you feel confident everything is in order, it's time to reconnect your PCV valve. Before you go on your test drive, make sure to attach the negative terminal. 

2. Replace Turbocharger

You can have the turbocharger repaired or replaced if you are certain that it is failing. The cost to replace the turbocharger can range from $750 to $1250.

However, it might not be necessary to replace the entire engine. You might be able repair the issue if you are skilled with turbos depending on what went wrong. 

3. Valve Seal Replacement

You should be able repair the leaky valve seals at your home using the correct tools. It can be expensive to get all the seals professionally installed. 

The cylinder head may need to be removed from the motor to access the seals. You can now inspect the seals of each valve for wear. You can remove worn seals if you find them. It's always best to replace all seals to prevent future problems, regardless of how expensive they may be for your vehicle. Normally the cost is minimal if the cylinder head doesn’t need to be removed.

RELATED: 5 Signs of a Bad Intake Manifold Gasket (& Replacement Cost)

4. Piston Ring Replace

Replacing piston rings can be the most expensive repair. The job can be costly and may cost anywhere from $1,000 up to $5,000.

To perform this repair you will need to remove the pistons and cylinders. Before you begin the repair, you will need to identify the worn rings using a compression test. Once you’ve identified the worn rings, you can replace them. Just like the seals, it’s best to replace all the rings to ensure they are in good shape.

5. Clean Oil Passages

Cleaning out oil passages within the engine is not an easy task. It’s not something for the faint of heart as it will take some time. You will need to remove any components from the front end of your engine before you can get going. 

It is also necessary to drain any oil remaining in the engine. After that, use wire brushes to access the passageways and clean them. If you aren’t sure what you are doing with the engine, you should never attempt to do this yourself. A small mistake can cause engine damage that could be very expensive. 

READ MORE: 6 Symptoms of a Bad Intake Manifold (& Replacement Cost)