Oil On Top Of Intake Manifold [5 Easy Solutions]

If there is oil on top of the intake manifold in your car, there could be a few reasons behind it. The most common reasons for oil ending up in the intake manifold are a damaged PCV valve, not changing oil, a jammed air filter, leaky intake manifold bolts, and leaky volt covers.

Keep reading to understand what causes the oil in the intake manifold and how you can solve these problems.

Oil On Top Of Intake Manifold [5 Easy Solutions]

We’ll discuss all the common reasons to explain what causes the oil in the intake manifold. The solutions for each of these problems are also provided.

1. Damaged PCV Valve

The burnt exhaust used to be released to the environment before PCV valves were used. The Positive Crankcase Ventilation valve was built to reduce carbon emissions. Instead of releasing the leftover gas through the exhaust system, the PCV valve sends it back to the engine via the intake manifold.

The job of PCV is to regulate the flow of air. The flow of air will be imbalanced if the PCV valve becomes damaged. A faulty PCV will cause the build-up of oil in the intake manifold.

Testing Whether PCV Valve Is Okay

A common sign of a faulty PCV valve is that your check engine light will be on. Test whether the PCV valve is working or not by is by removing it from the hose it is attached to. It’s working if you can hear a metallic sound. You have a malfunctioning PCV valve if you don’t hear the noise. 


The first thing you should do is clean the PCV valve. There’s a chance that you can salvage it if it hasn’t been heavily clogged. Try cleaning it and see if it works. Your problem should be solved if it’s working.

You’ll have to replace it if you can’t fix it by cleaning it. You should check the PCV valve at regular intervals to make sure this doesn’t happen again. It’s also a good idea to replace the hose around it as it can get damaged from time to time.

2. Not Changing Your Engine Oil

The oil passage of your car’s engine can become clogged if you don’t change the engine oil with time. The rusty oil will accumulate as sludge and it’ll block oil from passing through it. Eventually, the oil will build up and move up to the intake manifold through the PCV valve.


You need to use the engine flush formula to get rid of this problem. Pour the mixture into the engine oil and run your engine a few times. This should clean up the sludge and open the pathway.

Change the engine oil once the passage is cleared. Keep changing your engine oil with time to avoid running into this problem.

3. Jammed Air Filter

The air filter ensures the proper mixture of air and fuel so that the combustion process goes well. It does so by preventing dust and debris from getting into the mixture. The air filter will become clogged over time as the dirt it has blocked will stay on it.

A jammed air filter will cause the engine to emit black smoke through the exhaust. The problem will eventually lead to the intake manifold and oil can end up in the intake manifold.


Clean your air filter from time to time. Replace it when it’s necessary. Replacing an air filter is pretty cheap. Replacing the air filter will save you from spending money on major repairs. 

4. Leaky Intake Manifold Bolts

The intake manifold has some bolts around it. It needs to be placed tightly. Otherwise, you can find oil sitting on top of intake valves. If the leak is coming from the bolts, you’ll be able to guess where it’s coming from. The concentration of oil will be the maximum in that area.


Identify the leaky bolts and snug them down with a sealer or gasket maker. The sealers are made of silicon. Make sure the bolts are clean and dry before you cover them with the sealants. Don’t overtighten the bolts. Doing that will also cause a leak of oil.

5. Leaky Valve Covers

The valve cover of your car’s intake manifold can leak oil if they are not sealed properly. Check the torque of your valve covers. Over torquing or under torquing the covers will cause the leakage of oil on the intake manifold.

Clean the valve covers and run your engine. You’ll see the formation of oil after a while if the valve covers are leaky.


Torque the valve covers correctly. Otherwise, they will leak oil. Use valve cover seals or gaskets on top of that to make sure that no oil leakage takes place.


Is it normal to have oil in the intake manifold?

Having a little oil is normal. But a pool or puddle of oil in the intake manifold can lead to a much bigger problem like engine failure.

How to clean oil out of intake manifold?

Using a degreaser is the best way to clean the oil. Turn off your engine and spray the degreaser. Wash it off with light mist using a hose. Run your engine for a while to let it dry.

What are the symptoms of oil leaking from intake manifold?

The most common sign is that your check engine light will be on and your engine will be overheated. You’ll also see white smoke coming from the exhaust and your engine will frequently misfire.

How often does an intake manifold need to be replaced?

The intake manifold should run perfectly for the first 50000 miles. But it’s not uncommon to see the intake manifold get damaged before that due to the excessive wear and tear it undergoes.


Now you know what causes oil on top of the intake manifold and what you can do to solve it. There’s usually no immediate consequence if this happens. But it’ll cause severe performance issues of your engine if you don’t get it fixed soon.

We hope the tips have helped you to solve the oil pooling on top of intake manifold problem. Leave a comment if you have any questions!

About John M

John contributed as a technical head at an automobile company just 2 years after his post-graduation in Automobile Engineering. He loves to lead a free life, so he left his job & started blogging. Now, he does research on every automotive problem, part & product and seeks a better solution & best products & shares his findings with his readers to help them as well as to minimize their struggle.

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