Oil Leaking On Exhaust Manifold – Causes And Fixes

After working for a certain time and distance, most vehicles may appear signs which seem to be undesirable.

Those occurrences mostly signify engine-related obstacles. One of them is the situation where oil leaking from exhaust manifold.

Although this phenomenon is popular, many auto owners don’t know the reasons and how to solve it.

Therefore, this post is going to present the basics of oil leaking on exhaust manifold cases, including a brief definition, possible sources, and resolvings.

What Is Oil Leaking On Exhaust Manifold?

Oil Leaking On Exhaust Manifold

As the phrase described, oil leak from exhaust manifold is the phenomenon where you can see oil condensing in the exhaust pipes and then dripping down all the ways you drive through.

In most cases, this problem can lead to even more significant complications for cars, so don’t be indifferent.

Note: don’t be confused with the muffler leaking water problem.

Possible Causes Of Oil Leaking On Exhaust Manifold

PCV Valve

The PCV valve removes exhaust gasses from the crankcase and then sends them to the intake manifold for re-ignition in another process, resulting in a cleaner and more efficient exhaust system.

If there is a blockage in this valve, it may cause an engine’s crankcase to be overpressurized. Subsequently, oil can be condensed into the vehicle’s exhaust system.

This clog may also potentially result in liquid buildup in the vehicle’s intake piping, throttle, or exhaust pipes.

Valve-Train Seal

The poor valve seal is one of the common causes of lubricant leaking. Simply put, oil loss results from adjustments in the seal’s structure, which can be size, elasticity, or flexibility.

Those elements could diminish gradually, affecting the oil entering amount and other lubricant drain complications.

A popular symptom of damaged valve seals is that outgoing fumes can be grey or blue. Oil leak in exhaust manifolds caused by valve-train seals usually occurs in old vehicles.

Head Gasket

A head gasket, placed between the cylinder heads and engine block, is an essential component for the progress of internal combustion.

This component aims to separate the coolant fluids and engine lubricant, ensure compression, and keep those liquids from dropping into cylinder heads.

As a result, when the head gasket is blown, perforations can make the oil engine flow into the cylinders.

The combustion chamber may overheat, which can end in overheated car issues. Later, this is a possible case that can make oil leaking out of exhaust manifold.

The Manifold

The manifold itself can be the cause of lubricant leaking. During the combustion processes, it is exposed to lots of continuous cool and hot temperature changes.

Therefore, the structure or its small components, including manifold bolts, screws, etc., can be cracked or damaged somewhere.

This undoubtedly affects the exhaust system, which can result in oil leaking onto exhaust manifold.

Piston Rings

Those metallic rings are intended to seal the combustion chamber, preventing combustion gasses from entering the engine crankcase.

Moreover, they help to prevent lubricants from flowing into the combustion chamber.

During operation, the rings move continuously and vertically based on the movement of the cylinders.

If those rings are damaged at a certain level after a long time of collision and heat-bearing, the oil leaking into exhaust manifold potentially occurs.


The piston is responsible for forming the combustion chamber together with the cylinders and engine cover in the internal combustion process. 

Occasionally, the piston’s head can be broken after transmission processes. Those cracks and space can let the oil appear in the chamber.

Only a part of the appearing oil in the combustion chamber participates in the burning process.

After that, the leftover flows into the exhaust manifold, even creating lubricant condensation in the release pipe.

Valve Guides

Valve guides are usually small metallic tubes, functioning as supporters to the valve steam. They help the valve work stably through proper positioning and reduce the heat created during combustion.

In addition, this component also helps prevent engine oil from going into the cylinder heads, which can later result in the exhaust system.

Like other components, those valve guides can be worn out and damaged. From there, the lubricants can penetrate the engine exhaust system.

The oil in exhaust manifold will happen if the leak is intense. A common symptom, in this case, is the grey fume pushed out.

Head & Block

An engine’s structural components include a block and cylinder heads.

For the engine to work at its best, these key structural elements must be in good condition, which means they aren’t clogged or ruptured.

Although it’s rare to happen, these structural element cracks occasionally come up. These engine block or cylinder head failures frequently cause oil to leak into the combustion chambers.

Later, the lubricant will pass downward and eventually appear in the vehicle’s tailpipes.

Troubleshoot Oil Leaking On Exhaust Manifold

Troubleshoot Oil Leaking On Exhaust Manifold

1. Detect The Cause

When you notice an oil leak from the drain, the first thing to do is to determine the cause. Ask the question, “Why does my car have oil in the exhaust manifold?”. Once we know where the problem lies, we can solve it properly.

Please consider the following steps.

  • Observe the signs: Is anything unusual besides having oil in the exhaust? For example, it can be gray or blue smoke.
  • Note those signs: This step is to backup for some necessary cases. For example, we need to contact a car repair shop if the damage is severe. We’ll tell them about the symptoms.
  • Check the parts: PCV valves, valve-train seals, head gaskets, valve cover gaskets, piston rings, pistons, manifolds, valve guides, cylinder heads and blocks.
  • Identify the root: Look for those components’ cracks, dust, and damage.

2. Fix Or Replace The Damaged Accessories

After identifying the part causing the above situation. Shall we see how that damage should be dealt with? As follows

  • PCV valve: Normally, it will be clogged. It’s simple to solve. We’ll remove and clean it. If it cracks, we should find a similar model to replace it.
  • Head gasket: Let’s find and replace a new one if the head gasket is damaged. When replacing, we need to take note of the order carefully, so we won’t get confused when reinstalling.
  • Valve-train seal: When seals are worn out, it’s best to replace them. We should go to a repair shop to do this because fixing this part requires certain skills. A mechanic has to disassemble the whole engine to fix it.
  • Valve guides: A common problem in this part is worn. We can replace it with a new one or repair it with resizing, knurling, etc. However, both repairing and replacing this part requires professional skills.
  • Piston rings, manifolds, pistons, head & block: If the fault lies in these parts, we should go straight to the repair shop. Although there are many tutorial videos on the internet, they all require a certain understanding of the engine. Also, fixing these errors takes time and calls for technical knowledge and experience.

3. Re-check After Repair

If we are replacing or repairing any part at home, be sure of the following

  • The correct order of installation of parts.
  • Tighten screws and bolts to ensure that the parts can work smoothly.
  • Check if there are any redundant parts after reinstalling.
  • After ensuring the above factors, start the engine. At this point, we will check the oil leak, fume color, abnormal noises, etc.

In case we take the car to the repair shop, make sure

  • Correct replacement of damaged parts.
  • Check if the symptoms are still present. For instance, smoke color and smell, noise, oil on exhaust manifolds, etc.


Oil leaking on exhaust manifold is not immediately dangerous but gradually destroys the engine performance, leading to more serious broken issues. Therefore, it requires timely recognition and precise solutions. 

Remember to look at the floor and the exhaust pipes to recognize the problem as soon as possible. To the causes that can be addressed ourselves, pay attention to the details and carefully solve them.

If the issues are more serious, don’t hesitate to contact experts to avoid further damage and failures.

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