Lawn tractor oil leak. Head gasket guide: can a blown gasket be fixed and does sealer work

Too Much Oil In Lawn Mower? Read Our Easy Fix It Guide!

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What happens with too much oil in the lawn mower? Well, too much of a good thing can be bad for you! Right? Well, the same law applies to lawn mowers and engine oil. An overfilled lawn mower oil tank will lead to performance problems, failed starts, or an oily overflow mess. And much worse!

So, what other engine issues arise from putting too much oil in a 4-stroke lawn mower? And are these issues easy to fix?

Too Much Oil In Lawn Mower

Overfilling a lawn mower oil tank will negatively affect engine performance and possibly prevent the mower from starting. Too much oil in a lawn mower can easily clog the air filter, foul spark plugs, and potentially cause a hydro-lock, which could bend the connection rods in a multi-cylinder mower.

The way 4-stroke oil works in a 4-stroke walk-behind single-cylinder mower or a multi-cylinder lawn tractor is surprisingly straightforward:

• Lawnmower engine oil lubricates the engine and helps to keep it cool.
• The oil tank on a lawnmower feeds oil into the crankcase, where it is placed under pressure by the down-stroke of the piston during the combustion process.
• The air pressure forces the oil upwards to lubricate the piston and cylinder, as well as the crankshaft and con rod (piston push rod).
• The crankcase has a ventilation valve (breather) that releases pressurized vapor, which forms an oily mist.
• A rubber hose connects the ventilation valve to the mower’s air filter housing and carburetor air intake.
• The crankcase vapor passes through the air filter to the carburetor, where it mixes with the gasoline that fuels the engine.

What Happens When You Overfill the Oil In Your Lawnmower?

Too much oil in a lawn mower crankcase causes the vapor released via the ventilation valve to become oil-rich, which clogs the air filter, creating an overly rich air-to-fuel ratio that fouls the spark plugs and causes the engine to smoke and run poorly. Extreme over-oiling will stall the engine.

With too much oil in the mower’s oil tank, an excess amount of oil feeds to the crankcase, effectively reducing the volume (air space) of the crankcase, which increases the pressure in the crankcase during the piston down-stroke.

• The increase in pressure will force the excess oil through the ventilation valve into the air intake. From there, it will clog the air filter.
• The oil-rich vapor (potentially pure oil in extreme cases of over-filling) will enter the carburetor and blend with the gasoline that powers the engine.
• The overly rich air-fuel mixture will enter the combustion chamber and foul the spark plugs, causing the engine to sputter and stall.
• A severely over-filled lawnmower oil tank (and crankcase) will cause a hydro-lock, where the piston cannot move due to excess oil filling the combustion chamber (between the cylinder head and the piston crown).
• A hydro-lock has a similar effect to a seized engine – the engine stalls and won’t restart.
• Attempting to crank the engine of a multi-cylinder mower when hydro-locking has occurred could bend the con rods (piston push rods).
• Hydrolocked single-cylinder lawnmower engines generally don’t suffer con rod bending.

How Do You Know If You’ve Put Too Much Oil In Your Lawn Mower?

You’ll know you’ve put too much oil in your mower when:

• The oil on the dipstick is above the upper indicator line.
• Excessive smoke emits from the exhaust.
• The engine runs roughly and sputters.
• The engine stalls and won’t restart.
• The spark plug is oily.
• The air filter is oily.

Can You Put Too Much Oil In Your Lawn Mower?

Yes! You can put too much oil in a lawn mower if you fail to limit the volume of oil poured into the oil tank to the amount specified by the mower manufacturer. And filling oil into the mower directly from a large oil can without checking the dipstick as you fill the tank can lead to over-filling.

Note: Consult your lawn mower owner’s manual for the correct oil volume and grade.

Oil volume ballpark – Lawn mower oil volumes generally vary between 15oz to 20oz, ranging from single-cylinder walk-behind mowers to larger multi-cylinder ride-on mowers.

What Are the Risks of Overfilling a Small Engine With Oil?

The risks associated with overfilling a small engine with oil include the following.

• Bent con rods – which may require expensive engine repair!
• Your lawn mower air filter may spoil.
• Your lawn mower spark plugs risk soiling.
• Wasted oil – the ultimate sin for thrifty homesteaders!

What to Do When You’ve Put Too Much Oil In the Lawn Mower? Easy Fix!

The best way to fix an overfilled lawn mower is to drain the engine oil from the oil tank, crankcase, and combustion chamber. Remove the air filter and spark plug and clean them to remove all traces of oil. Crank the engine several times with the spark plug removed to purge residual engine oil.

How to Fix a Failed Mower Engine Due to Oil Overflow?

Do you need to fix a lawn mower that’s stopped running due to oil overfilling? Then follow these steps.

Get the Right Tools, Including the Following:

• A jug or can of the specified oil for your mower.
• A spark plug wrench.
• A screwdriver or wrench. These tools help to remove the air filter.
• A wrench! Wrenches are perfect for removing the oil drain plug.
• Pliers to remove the ventilation hose.
• A solvent. It helps to clean the lawnmower spark plug.
• Detergent! Warm water with grease-cutting soap works fine. It helps to clean the air filter.
• A plastic funnel.
• An oil drain pump – but only if the mower lacks an oil drain plug.
• An oil drain hose – is critical for ride-on lawn tractors.
• An oil drain pan.
• A measuring jug.
• Paper towel.

Troubleshooting Your Lawn Mower – Step-by-Step

• Disconnect the spark plug boot and remove the spark plug from the engine.
• Remove the air filter cover and ventilation hose.
• Remove the air filter.
• Clean the spark plug.
• Clean the air filter and dry it with a paper towel.
• Lightly oil the air filter to prevent it from drying out and perishing.

Drain All the Oil From the Crankcase and Oil Tank – Step-by-Step

• Remove the oil drain plug (on the side of the engine or under the deck) and drain the oil into an oil drain pan (large mowers may need an oil drain hose to attach to the oil drain valve).
• Pump oil out of the oil tank (for mowers without an oil drain plug) into an oil drain pan or disposable bottle.
• Tip the mower on its side with the oil tank cap removed (for mowers without a drain plug). And drain oil from the oil tank and crankcase into an oil drain pan.
• Crank the engine several times to vent oil vapor from the spark plug hole and crankcase ventilation hose.
• Let the mower stand with the spark plug, oil drain plug, and air filter removed for 45 minutes to evaporate oil-vapor residue.
• Refit the cleaned spark plug, air filter, and ventilation hose.
• Screw in the oil drain plug.
• Pour the manual-specified amount of oil into a measuring jug (you can DIY a used canned fruit tin or similar).
• Fill the oil from the measuring jug into the oiling tank via a funnel.
• Allow the oil to settle for two minutes.
• Screw in the dipstick and oil cap.
• Unscrew the dipstick and check the level. Top up if necessary. But don’t go over the upper marker line on the dipstick.
• Screw on the oil tank cap.
• Crank the engine. The mower should start.
• Allow the mower to idle for a few minutes.
• Smoke will emit from the exhaust as the engine burns away the remaining oil residue.
• Stop the mower and check the dipstick. Top up the oil if necessary using the measuring jug.
• Cut the lawn!

Conclusion – Re-Oiled and Ready to Mow

If you’ve overfilled oil in your lawn mower, don’t beat yourself up – it’s a common mistake! And, the remedy needn’t cost much more than the price of a new can of oil.

Irrespective of what type of mower you own, having the right tools for the job and following our step-by-step oil overfill fix will get your mower back into the field. Pronto!

In the meantime, let us know if you have more questions about what to do if you put too much oil in the lawnmower.

We have tons of experience tinkering with lawn mowers, tractors, engines, and small farmyard equipment.

And we’re always happy to help troubleshoot.

Too Much Oil In the Lawnmower References, Guides, and Works Cited:

Authors

Dan is our qualified diesel fitter and automotive mechanic. He’s been fixing machinery for over 30 years and has a real passion for the old stuff. he loves reviving things that others have given up on. He’ll fix anything with a cable tie and fencing wire and has had his hands on everything from log skidders, trucks, agricultural implements, tractors, and huge mining gear to outboard motors. He’s plagued by OCD. but that makes him a helluva mechanic! View all posts

Paul writes for a living, about trucks mostly. He lives away from the city and off the road, nurturing his love for all things outdoors –- like tiny house construction, country cooking, bushcraft, woodwork and power tools, alternative energy, and minimalist living. If there’s a way to Do It Yourself, Paul wants to hear about it, and try it out. Then he’ll write about it, and share his story with blog readers around the world. Paul was raised on a South African homestead where he tended two horses, a Jersey cow, and half a mile of split pole fencing. At age 16, he bought a dirt bike, pirated a punk rock compilation, and commenced a blind-rise adventure that continues to this day where words, Wabi-Sabi, cooking, all-terrain tires, and all things to do with canvas and wood are his fodder. His overarching existential question is – “What more does a man need than a cast iron pot and a pair of loose-fitting trousers?” View all posts

Head gasket guide: can a blown gasket be fixed and does sealer work?

A head gasket sits between a car engine’s cylinder head and block – and should be able to do its job for tens of thousands of miles without a problem. So what are the signs of a blown head gasket and why does it fail? This expert guide for DIY mechanics will answer all of your questions about how head gasket sealer works, head gasket repair cost and head gasket symptoms.

What is a head gasket?

A head gasket sits between the cylinder head and the block. Its job is to seal the two mating surfaces of the top and bottom halves of the engine.

This means, unlike any other gasket in an engine, the head gasket has to seal oil, coolant, and compression from the cylinders simultaneously. This makes it the most stressed gasket in an engine, and therefore one of the most likely to fail. Some engines have a reputation for getting through head gaskets rather quickly but others have gaskets that will never have to be changed.

How does a gasket work?

The head gasket needs to seal the oilways between the cylinder head and block, so that oil can freely circulate around the entire engine. It also needs to do the same with the waterways, so that coolant can also circulate freely around the engine.

But what makes a head gasket different from any other gasket is that it also needs to seal the cylinder to prevent the engine losing compression.

Inside an engine you have a piston going up and down within a cylinder. On top of the cylinder you have the cylinder head, which allows the fuel/air mixture to enter, and the exhaust gases to leave via inlet and exhaust valves. Without a good seal between the cylinder head and the cylinder, when the piston rises on the compression stroke some of the air/fuel mixture will be able to escape, resulting in a loss of compression.

In order to form a good seal around the top of the cylinder, the head gasket features steel rings, known as fire rings. These are actually crushed when the cylinder head is tightened onto the engine block to provide a seal capable of dealing with the high temperatures and pressures involved.

This is why you must always tighten the head bolts to the required torque settings you’ll find in your Haynes Manual; too tight and the gasket will be crushed too much to form a proper seal, too loose and it won’t seal enough.

How can a blown head gasket be repaired?

Head gasket repair has to be performed properly. If it’s not, there’s a risk it’ll have to be redone. At the very least, the cylinder head must be removed along with the old gasket. Then the cylinder head and cylinder block mating surfaces must be thoroughly cleaned before a new gasket and the cylinder head can be refitted. It’s also advisable to flush the coolant system to remove any gunge that could cause a blockage. However, while it’s removed, the cylinder head must be checked for distortion, and it’s common to have the mating surface skimmed to ensure it’s perfectly flat. In some cases, the vehicle manufacturers insist that the cylinder head cannot be skimmed, but must be renewed. If the vehicle is old, the cost could mean the car is an insurance write-off.

Head gasket repair cost UK

The head gasket itself is a comparatively cheap part – as little as £20-£40 in most cases. However, the labour involved by getting a garage to do it for you will land you with a final bill that’s likely to exceed £500. Luckily, if you’re a competent home mechanic, or have a friend that is and is willing to help, you can change your Every Haynes manual walks you through the process of head gasket replacement as part of the ‘cylinder head removal and refitting’ procedure. Find your print and online manual here and save yourself hundreds of pounds.

How long does it take to fix a blown head gasket?

Replacing the gasket can take anything from six hours to a few days, depending on the severity of the failure. A blown head gasket is one of the biggest failures your car can suffer, and to fix it properly takes time. Again, check your Haynes Manual to get an idea of the time involved.

Can I use head gasket sealer?

We don’t recommend head gasket sealer because it only delays the inevitable and can cause complications elsewhere in the coolant system. How does head gasket sealer work? It’s introduced into the radiator or coolant reservoir. The engine is then started and run for around half an hour with the ventilation heat and fan speed turned up to max. The sealant works its way through the engine and into the faulty parts of the head gasket, and then sets, creating a temporary seal. However, it’s just that – temporary – and could fail at any time, leaving you (quite literally) in more hot water than you were in before. Sealers also have a tendency to block small coolant passages, so you could end up with more blockage problems, which could lead to overheating.

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Back Yard Tips

Explore our collection of helpful information from some of the best horticultural minds around. All focused on how to make your yard beautiful.

A smoking lawn mower is never a good sign. Whether the smoke is blue, white, or black, here’s how to identity and address the issue without the help of a professional.

By Glenda Taylor and Bob Vila | Updated Sep 24, 2020 1:40 PM

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Q: Recently, my mower started billowing smoke when I powered it up, so I shut it off immediately. Why is my lawn mower smoking? And is it a fire hazard? I want to know how to proceed so I don’t harm the machine.

A: Your lawn mower can emit smoke for numerous reasons—many of which don’t require the services of an expert. A homeowner can usually identify the reason for a smoking lawn mower by gauging the color of the Cloud coming around the engine, then fix it accordingly before lasting damage occurs. Keep in mind that all mowers with internal combustion engines contain the same basic parts, but the configuration of those parts varies widely, depending on manufacturer and model. Consult your owner’s manual if you’re unsure how to access a specific part of your lawn mower’s engine.

White or blue smoke may indicate an oil spill on the engine.

If you’ve recently changed the oil in your mower and the engine is emitting white or blue smoke, it’s possible that some of the oil spilled onto the engine. Similarly, you could’ve spilled oil on the engine by mowing on a slope greater than 15 degrees or tipping the mower on its side. The smoke may look disconcerting, but it’s completely harmless. Solve the problem by restarting the mower and allowing the spilled oil to burn off. If you tip the mower often for cleaning or maintenance, check your owner’s manual to determine the best way to reduce the risk of oil leaks.

An overfull oil reservoir may also cause white or blue smoke.

Ensure you didn’t overfill the mower by checking the oil level with the dipstick located on the reservoir. To do this, remove the dipstick cap, wipe off the stick with a rag, and reinsert it into the reservoir. Then remove the dipstick once again and determine the oil level in comparison to the recommended “fill” line on the stick. If the level is too high, drain the oil (consult your owner’s manual for instructions), then refill the reservoir with it. Start checking the oil level with the dipstick after you’ve added about ¾ of the amount recommended in the manual. Continue to add small amounts of oil until the level matches the recommended “fill” line. Also note that using the wrong grade of engine oil may cause blue or white smoke. Consult the owner’s manual for the exact type of oil recommended for your mower.

Black smoke may indicate that the mower is “running rich,” or burning too much gasoline.

Your lawn mower’s carburetor regulates the ratio of gasoline to air mixture. If the carburetor isn’t getting enough air, the mixture has a higher percentage of gasoline, which can create black exhaust smoke. It’s possible that a dirty or clogged air filter is preventing sufficient airflow into the carburetor. Try replacing the air filter. (Note: air filters vary by mower model; view example air filter on Amazon.) Next, run your lawn mower for a few minutes. If the black smoke still appears, the carburetor might need to be adjusted in order to increase airflow. Either take the mower to a professional or adjust the carburetor yourself with instructions in your owner’s manual.

Take your mower to a repair shop if necessary.

If the previous steps don’t correct blue or white smoke, your mower could have a more serious problem, such as an air leak in the crankshaft (the cast iron or cast aluminum case that protects the moving parts of a mower’s engine). Continuing blue or white smoke could also indicate that some of the engine’s components or seals are worn out and need replacement. Similarly, if black smoking still persists after you’ve replaced the air filter and adjusted the carburetor, you could be facing a more serious mechanical issue. All of these problems require the help of a professional. If your mower is still under warranty, check with the manufacturer for the location of the nearest servicing dealer; problems stemming from a factory defect or poor workmanship may garner free repairs. If your mower is not covered under warranty, a reputable small-engine repair shop should also be sufficient to get the job done.

Why Is My Oil Filter Leaking?

sefa ozel/Getty Images

An oil leak can leave a few drops or a big puddle under your engine. Ignoring a leaky oil filter can quickly lead to expensive engine damage.

There are seven common reasons why an oil filter leaks. Knowing the possible causes will help you determine what steps you should take to correct the problem.

To remove contaminates before it starts its lubricating cycle, motor oil is fed directly from the oil pump through the oil filter. Under full oil pressure, a seemingly minor oil filter leak can quickly turn catastrophic. Unless oil is gushing from the oil filter, in most cases replacing an oil filter is a DIY operation. Never try to repair or reuse an oil filter.

Double Gasket

The most common mistake that happens while changing the oil filter is the “double gasket.” This happens when an oil filter is replaced. The old filter gasket sticks to the engine, and the new oil filter and gasket are installed on top of the old one.

After removing the old filter, check that its gasket is still mounted on the filter. If you accidentally double-gasket an oil filter, hopefully it will blow out (creating a nasty mess) as soon as the engine starts and not as you’re driving down the road.

Oil Filter Gasket

Check the rubber mounting gasket to make sure it is not cut, nicked, twisted or damaged in any way, and is properly seated and snug in the filter baseplate. Always install a new filter if the gasket is bad.

Be sure to clean the area where the gasket contacts the engine of dirt and grime and completely remove any old gasket material that may stick to the mounting surface. Use a degreaser to clean the gasket-contact surface and use your finger to spread a thin coat of new oil on the gasket before installing a new filter.

Over- or Under-tightening

Besides making it difficult to remove when replacing the oil filter, over-tightening can crush the filter gasket, causing it to leak. When not properly tightened, any vehicle part designed to seal against a leak will loosen from normal engine or driving vibrations and cause leaks.

Oil filters should be “hand tight” and then given a one-quarter turn to securely fasten without being too tight. Never use an oil filter wrench to tighten an oil filter — only to remove it.

Oil Filter Mounting Adapter (Filter Housing)

To mount an oil filter, some manufacturers use a filter adapter or housing that bolts to the engine, rather than attaching directly to the engine. Over-tightening the filter can damage not only the oil filter gasket, but the gasket between the adapter and engine.

Check that the nipple onto which the filter threads is tight inside the adapter. Nipples can be threaded on both sides and can loosen when unscrewing the old oil filter. The filter gasket may not fully seat if the threads are loose and leak. Leave this fix to your mechanic.

Damaged Threads

An oil filter’s baseplate threads are softer than the threads on the mounting nipple and can be cross-threaded if the oil filter is screwed on crooked when it’s installed. You’ll need to install a new filter if the threads are damaged. If you screw on the new filter without any problems, and there are no apparent oil leaks, it’s still a good idea have your mechanic check out the filter mounting nipple threads for damage.

Wrong Filter

Check your owner’s manual for the correct filter number for your specific engine. A filter may feel as though it is tight when installed, but the threads may not be exactly the same as the mounting nipple. This will cause the filter to loosen up and leak over time.

Also, the wrong filter may have the incorrect by-pass valve. The by-pass value opens to protect the engine from oil starvation if the filter becomes clogged. If you’re not sure you are installing the correct filter, leave it to your mechanic.

Damaged Oil Filter Housing

A rock, stone or road debris can puncture the oil filter outer housing shell. If oil is spurting from the filter, turn your engine off and immediately call for a tow to your repair shop.

Is it the Filter?

Oil from the oil pressure sensor, or just about any other engine gasket or seal, can leak over the oil filter. If the oil filter itself is not leaking, it’s important your mechanic verifies which seal or gasket is the culprit.

The most common cause of oil leaks is lack of maintenance. Going too long between oil changes causes oil to break down and become contaminated. Contaminated oil attacks and degrade gaskets and seals, which results in oil leaks.

An oil filter removes contaminants from engine oil. Replacing the oil filter every time the oil is changed is one of the least expensive and most effective ways to prolong engine life. Always follow local guidelines to properly dispose of used motor oil and filters. If you’re unsure what is causing a leak, have your mechanic check it out. Repairing leaks will save you from costly repairs.

Bob Lacivita is an award-winning ASE and General Motors auto technician, educator and freelance writer who has written about DIY car repairs and vehicle maintenance topics. His work has been featured in The Family Handyman, a Reader’s Digest book and Classic Bike Rider magazine. He has been a career and technical educator for 25 years teaching automotive technology, as well as writing state, federal and organizational foundation grants. He also helped design a unique curriculum delivery model that integrates rigorous, relevant academic standards seamlessly into career and technical education.