Lawnmower Oil Leak – How to Fix Yourself - Fast & Cheap

Lawnmower Oil Leak – How to Fix Yourself

lawnmower oil leak

why is oil leaking from my lawn mowerA lawnmower oil leak is not only a messy problem but can spell a bigger problem than just simply drip drip. And when this problem occurs in the engine, the performance of the lawnmower will eventually fail, and worse, the engine can even get damaged. Oil can  leak from different parts of the lawnmower like the exhaust, carburetor, and air filter. If this happens, you must do a quick inspection, cleaning and fixing or even replacing of broken parts. 

There are a lot of causes why oil leaks happen and this is the best time to answer the most common questions by many of our readers – why is oil coming out of my air filter on my lawn mower, why is my lawn mower leaking oil from the exhaust, and why is oil coming out of my carburetor on my lawn mower.   

Why Is Oil Leaking from My Lawn Mower

According to many experts, the most typical causes of oil leak from the engine can be due to worn-out engine gaskets, degraded or improper sealing of seals, and the lack of maintenance, especially the need for regular changing of engine oil. When oil doesn’t get replaced when it’s due, it will get contaminated and can destroy seals and gaskets resulting in oil leaks from different parts of the engine.  So if you’re asking why is oil leaking from my lawn mower, usually this is one of the causes brought about by dirty oil. The engines have become toxic to the gaskets and seals.  

Nevertheless, there are also other causes for oil leaks with lawnmowers. But when these happen, you can easily see the problem right on the spot. You may see some specks of oil on the cement floor the first time but in a few days, the spot can become a small pool of oil.

What Happens When Lawnmower Oil Leaks

Most of the time, people who use mowers don’t realize that their machine is leaking oil because they don’t see the drips on the grass as they mow. And if they park their machines on the ground, the oil leaks get absorbed by the soil and it quickly disappears. 

Oil leaking from the lawnmower can bring the machine to a halt due to overheating. Beginning with the crankshaft, the piston and piston rings will bear the consequences. And as the metals inside the engine grind on each other and produce friction, This can mean the end of your lawnmower. 

The leaking engine oil can deprive the engine of its power because a lack of lubrication will prevent the engine’s parts from moving smoothly. And if you force the engine to run, further damage can happen and can destroy the engine block for good.  

How to Determine Lawnmower Oil Leak

lawnmower oil leakIf you suspect that your machine is low on oil but don’t see any leak on any of its parts, the best way to determine a lawnmower oil leak is by relying on the machine’s dipstick. Every dipstick has a gauge which tells the maximum amount of engine oil level that’s in the engine. So if you see that the dipstick is not reaching any oil level and comes out dry, your engine needs engine oil refilling badly.  Checkout How Often To Change Lawn Mower Oil here.

Another way of knowing if your lawnmower is leaking oil is by observing the performance of the machine. If there is a clunking sound like metal grinding or the engine is overheating quickly, better check the oil level of your unit immediately. Don’t forget to observe your lawnmower where you’re leaving it because oil tends to leak faster while the engine is at rest and when the oil is warm. 

Lastly, always double-check the machine for signs of oil leaks before and after using it, and don’t just check the underside of the engine because leaks can occur on the exhaust, air filter and, in the carburetor. See How To Drain Oil From Lawn Mower Here.

Why is My Lawn Mower Leaking Oil from the Exhaust and How to Fix It

People get concerned and ask why is my lawn mower leaking oil from the exhaust? Well, this happens for a number of reasons. It could be caused by tilting the machine on its side and some of the oil shifted to the exhaust part of the engine. It could also be that the crankcase is overfilled with oil that there’s no other way for the oil to go but to come out from the exhaust. And the other possible cause of lawnmower oil leak on the exhaust is a damaged piston rings.  

When oil gets into the exhaust, smoke is produced and the color of the smoke can indicate the most possible causes.  

Black smoke.

If the black smoke comes out for a brief moment from the exhaust, there is nothing to get alarmed at. This means that the carbon from the burnt fuel that has accumulated in the exhaust was suddenly released. But if the release of black smoke continues, that means the contaminated oil has reached the exhaust system and also contaminated the air filter.   


To prevent lawn mower oil leaks from reaching the exhaust, you must regularly change the oil of your machine for every 100 hours of use or every season that you use your lawnmower. Do not add new oil to the old oil otherwise, the sediments that have formed inside the engine will produce blockage to the tubes and joints and will cause leaks. Some of these leaks can reach the exhaust system of the lawnmower.   

White smoke.

 If your lawnmower is a riding type, leaking oil from the exhaust and producing white smoke can indicate a damaged head gasket. The gasket is usually made of metal and graphite and is located between the cylinder head of the engine and the engine block. This part is designed to prevent the leakage of coolant and engine oil from coming into the cylinder while sealing the cylinder to reach its maximum compression. 

What happens when the gasket gets damaged is that the burnt coolant can seep into the engine and make it overheat which in the long run can damage the engine itself. In this case, white smoke may come out from the exhaust due to the mixing of coolant and oil. 

If your lawnmower is a self-propelled type, white smoke coming out from the exhaust can mean your machine has an overfilled oil in its reservoir or the same, damaged gasket. 


To solve the riding lawnmower oil leak, the gasket must be replaced. So if the engine always overheats and releases white smoke, check the gasket as soon as possible. Also, do not overfill the coolant cylinder to avoid a leak. 

For the self-propelled lawnmower, just release some of the oil little by little from the reservoir and use the dipstick to gauge until the optimum level is reached.  The optimum level is the first line you’ll see on the dipstick. 

Gray or Blue Smoke.

When this type of smoke comes out from your lawnmower’s exhaust, this may mean there’s oil leaking and getting burned in the combustion chamber along with the air-fuel mixture. This problem can damage the catalytic converter and hamper the release of hydrocarbon thus the result is blue or gray smoke getting released thru the exhaust. 


The best thing you can do to prevent future oil leaks from the exhaust is by replacing the crankshaft oil seal on both ends of the crankshaft that may have already corroded. Then drain out the oil completely and refill with high mileage motor oil. 

Why is Oil Coming Out of My Air Filter
on My Lawnmower and How to Fix It

To answer the question why is oil coming out of my air filter on my lawnmower, according to experienced lawnmower owners, there are two ways why oil comes out from the air filter. 

Leak Near the Carburetor

When you fill the oil cylinder with oil, the oil will travel to the crankcase. But before this will reach the crankcase, it must also pass the breather cavity. This cavity has a filter composed of small holes. However, when these holes get plugged up with dirty oil, the oil can flow back into the oiling system and will produce a leak near the carburetor as well as on the air filter. 


The only solution to this problem is by removing and cleaning the breather cavity with a rag and using a metal wire to clear out the holes. The breather cavity is located underneath the oil tank of the engine. Drain the oil out, clean out the air filter like washing or replacing if necessary and refill oil using fresh engine oil only. 

Problems With the Oil Pump

lawnmower oil leakWhen oil leaves the tank and goes to the pump, it will be pushed into the crankcase. However, if the dirt on the oil gets the pump clogged, the oil may flow back and go to different areas of the engine including the air filter compartment. And this is how oil leaks can happen through the air filter. 


The engine may need to be disassembled to get access to the oil pump. This may require the help of a mechanic.

Why is Oil Coming Out of My Carburetor on My Lawn Mower and How to Fix It

lawnmower oil leakThe same as we discussed above when oil travel from the oil cylinder but must pass the breather cavity to reach the crankcase and the breather cavity gets clogged with sediment caused by contaminated oil, some of the oil may backflow and some of it may reach the carburetor.  And because the carburetor has small inlet tubes where the gas flows, the sediments can also clog up these inlets and will cause carburetor and engine flooding. 


To fix this kind of lawnmower oil leak, clean the breather cavity as discussed above and disassemble the carburetor and clean it with a carb cleaner. Check the inlets of the carburetor and detach the bowl located on the belly of the carburetor by unscrewing its nut. There’s a hole on this screw that maintains the air pressure inside the carburetor so clean this with a pin before reattaching it to the bowl. Drain the oil and better drain the gasoline as well from the tank to release any possible contamination. 

If you still have the user’s manual of your lawnmower, don’t hesitate to check for the troubleshooting tips especially if you see signs of oil leaks. And if your lawnmower is still under warranty coverage, call the customer service right away for free advice or repair service if necessary or probably for parts replacement. 

Conclusion on Lawnmower Oil Leak:

Some of the causes for lawnmower oil leaks can be easy or hard to fix depending on the parts that need to be fixed. Lawnmower parts are replaceable and the only thing you must do is to find where the problem is coming from. So don’t feel bad when you see some oil leak signs with your lawnmower because some of the causes can be easily fixed.