Causes and Fixing of Oil Leaking on Exhaust Manifold

Oil leaking on exhaust manifold has serious implications if not rectified immediately. The exhaust manifold is designed to collect exhaust gases from the engine cylinders. It further directs them to the exhaust system.

When oil leaks onto the manifold, it can create various problems. The combination of heat from the manifold and oil can lead to burning smells, smoke, and even potential fires.

Additionally, oil leaking out of exhaust manifold can affect the engine’s performance.

This article will explain why and how oil leaks on the exhaust manifolds and the possible ways to rectify the problem.

oil leaking out of exhaust manifold

Causes of Oil Leaking on Exhaust Manifold

A clogged PCV valve is one of the most common causes of oil coming out of exhaust manifold. Other causes include; a cracked head or engine block, worn valve guides, bad valve cover oil seal, and a defective manifold.

Clogged PCV valve 

The PCV system removes blow-by gases from the crankcase and recirculates them back into the engine for combustion.

If the PCV system becomes clogged or fails, pressure can build up in the crankcase. This can cause oil to be forced out and potentially leak onto the exhaust manifold.

The manifold

Oil leak on manifold can also be caused by a defect in the manifold itself. The reason is that the manifold is exposed to a consistent interchange of cool and hot temperatures.

The temperature fluctuations can result in a crack or damage to the structure of the manifold screws, bolts, gasket, etc. When this occurs, you will most likely have lubricant leaking onto the exhaust manifold.

Bad valve cover seal

The valve cover oil seal is an essential engine component for sealing the cylinder head and the valve cover. It is found on the valve cover. Unfortunately, the seal is susceptible to wear and tear, which affects its elasticity, size, and structure.

When the valve cover seal wears out, its compromised nature can result in oil leaking onto exhaust manifold. In most cases, oil leaking onto the valve cover results from leaking valve cover oil seal.

Cracked head or engine block

A vehicle’s engine is built with a block and one or multiple cylinder heads. These components help to maintain efficient engine performance. Unfortunately, cracks can occur within the cylinder heads or the engine block due to overheating.

These cracks can result in the loss of engine oil in the combustion compartment. When this occurs, leaking oil can find its way down to the exhaust manifold.

Power steering pump leak

The power steering is an essential part of the steering system. It houses and pumps the steering oil to other steering components like the rack and pinion. If the pump is overfilled or leaking, it may spill oil on the exhaust manifold.

How to Fix Oil Coming Out Of Exhaust Manifold

Early diagnosis and repair will help prevent oil leaking on the exhaust manifold from causing severe damage. Therefore, the following are some recommendations to help you fix the issue immediately.

Inspect the power steering pump

Examine the power steering pump reservoir and see if there are any oil leaks. Check the pipes that connect to the steering rack and pinion for leaks. If there’s a leak in any of these areas, the leaking fluid can be dripping on the exhaust manifold.

If you spot any leak, fix it as needed. Often, all you need to fix the problem is to reduce overfilled fluid or bleed the steering pump.

Clean the PCV valve

Typically, you can locate the PCV valve on the intake manifold. Take it off of the valve cover while leaving the hose attached. Then, place your finger over the open end and check if it suctions. Once it is verified, it means the valve is okay.

If it doesn’t suction, ensure to clean it. You can use a carburetor or brake cleaner to remove debris or dirt. Then, blow off the fluid with compressed air. If this doesn’t work, kindly replace the PCV valve.

Inspect the valve cover

Visually inspect the valve cover and see if there are any oil leaks around the area. If engine oil is dripping from the valve cover, the valve cover oil seal is the culprit.

Loose the bolts holding the valve cover and inspect the oil seal. If the seal is dry, brittle, or broken, replace it. But if the seal is still okay, remove it and clean it properly. After that, reinstall it on the cover and apply a slight sealant to it. Install the cover.

Check for other damaged components

Now, carefully perform a physical check on other components within the engine compartment. Inspect the intake manifold, engine block, cylinder head, etc.

Once you identify a faulty or damaged part, replace the component as soon as possible.

Contact an expert auto technician

Finally, if you’re not sure of accurately diagnosing and fixing the exact cause of the problem, ensure to contact a professional auto mechanic for help.

It’s okay to reach out to a mechanic if you don’t feel comfortable doing any task, no matter how easy it may be. You don’t want to cause more damage in the long run.

How Much Does it Cost to Fix an Exhaust Manifold Leak?

The cost of fixing an oil leak on an exhaust manifold can vary considerably depending on various factors, including the severity of the leak, the make and model of the vehicle, labor rates in your area, and whether any additional parts are affected or need to be replaced.

Generally speaking, you might be looking at the following potential costs:

Diagnosis: Before any repairs are carried out, a proper diagnosis needs to be done to pinpoint the exact cause of the leak. This could cost anywhere from $50 to $100.

Gasket Replacement: If the oil leak stems from a faulty gasket, replacing it might cost between $200 and $400, including labor and parts.

Oil Line Replacement: Sometimes, the oil lines might be the culprit. Replacing them could set you back between $100 and $300, depending on various factors.

Exhaust Manifold Repair/Replacement: In more extreme cases, if the exhaust manifold itself needs to be repaired or replaced, this could cost between $250 and $900.

Miscellaneous: Apart from the above, other minor repairs and parts replacements might be necessary, adding to the total cost.

Please note that these are just general estimates, and actual costs can vary. It is always best to get quotes from a few different repair shops to better understand the potential costs in your specific case.

Is it Bad to Drive with an Exhaust Manifold Leak?

Yes. Driving with an exhaust manifold leak can cause severe carbon monoxide poisoning. A leak in the manifold will most likely allow gases to enter the passenger compartment. This can be harsh to the eyes and even dangerous to the respiratory system.

On the other hand, oil in exhaust manifold signifies a problem within the engine compartment. Oil dripping on a hot exhaust manifold can cause a fire outbreak.

Can Oil Leaking on Exhaust Manifold Cause Fire?

Yes, oil dripping on exhaust manifold can trigger a fire outbreak. This can be very dangerous, so why you should track the root cause and fix it once you spot it. As the heat on the exhaust manifold intensifies, it can trigger an open flame within the exhaust system.

Fire outbreak is a latter consequence of exhaust manifold leaking oil. In other words, a driver should have observed other early symptoms like the burning odor emitting from the engine bay.


Driving with oil leaking out of exhaust manifold is like a time bomb waiting to explode. However, this occurrence comes with symptoms that enable you to identify and fix the cause immediately.

Address the cause of the issue to avoid triggering other faults, or else it can gradually damage your car’s engine. So, take swift action and fix the problem to avoid costly engine repair or replacement.

While it may seem easy to fix this problem, feel free to contact a certified mechanic if you’re not okay with the task.


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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