its a cylinder problem
Bilt 5.5hp Self Propelled Mower

Experienced gardeners share their insights in answering this question :
What do you mean by blowing oil?Do you mean when you run it,oil splatters everywhere,like on your legs and everywhere?Is it localized to one spot or all around?

How to Identify and Fix Common Gardening Problems ?

We provide a variety of viewpoints on how to identify and fix common gardening problems. Our sources include academic articles, blog posts, and personal essays from experienced gardeners :

Broken Seals on a Troy-Bilt Mower

Broken seals and gaskets also cause mowers to smoke. A broken diaphragm gasket in the carburetor allows too much fuel into the combustion chamber. Broken piston parts like cylinders, rings and gaskets will leak fuel into the exhaust or muffler, causing smoking.

If it`s clogged, the combustion chamber may not be getting enough oxygen, resulting in a too-rich fuel mixture that will cause the engine to run poorly and even spew smoke. The solution is to change the air filter, a relatively easy task. Blue and white smoke is the result of oil on the engine.
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.
White Smoke

In extreme cases, you will need to replace your head gasket. At the first sign of white smoke you can try head gasket repair treatment to seal the leak before you do serious damage to your engine.

What causes lawn mower smoke (and what to do about it) In the majority of cases, a lawnmower engine suddenly bellows out blue or white smoke because oil has spilled onto the engine. The spillage can happen if you added or changed oil and slopped some or overfilled.
Blue or white smoke coming from your engine usually indicates burning oil, which can be caused by: Overfilling the crankcase with oil. Incorrect oil grades. Operating engine at greater than a 15 degree angle.
Clogged or Dirty Air Filters

It is one of the most common problems that cause lawnmowers to sputter. The mowers take the air from the surrounding through air filters and mix it with fuel inside the engine. So, if the air filter is clogged or dirty, it will affect the flow of air into the carburetor.

Clogged or Dirty Air Filters

Dirty air filters are one of the most common reasons lawn mowers sputter. Dirt can be present in the apertures that lead from the carburetor and the fuel filter and interrupt the flow of fuel supply to the combustion chamber. You want to be sure to clean or replace dirty air filters.

A burning rubber smell

If your car smells like burning rubber, turn off the engine and check under the hood to see if anything looks out of place. Chances are that the smell results from a belt or other part slipping and rubbing against the hot engine. If you can`t identify the problem, take your car to a mechanic.

If your engine smells of burning or smoke, there are two possible reasons for this: it`s overheating or there`s a problem with the oil. Generally if it`s overheating, you`ll know about it because a warning light should appear on the dashboard.
Black exhaust smoke

When your exhaust pipe gives off black smoke, one of the things to get worried about are bad or worn out spark plugs. It means fuel burning in the combustion chamber is not being done 100 percent or burnt fully. It also means that air is not being well mixed with fuel to burn effectively.

Sign #2: You Can See (And Smell) Engine Exhaust

So if you see anything that looks like smoke, it could be a sign that the oil is old (if it`s not a sign of a major mechanical fault like a cracked head gasket). Ditto for if you can smell any hint of burning oil in your exhaust.

The easiest way to diagnose gas is to smell the fuel in question. Oxidized gas has a sour smell and is much stronger smelling than fresh gas. The other method is to drain a sample from your machine`s fuel tank or your gas can into a clear glass container. If the gas is dark in color, it has more than likely gone bad.
Dirty air-filters that do not allow sufficient air (oxidant) into the combustion chamber for complete combustion of the fuel charge contribute to black smoke.
White smoke can often mean material is off-gassing moisture and water vapor, meaning the fire is just starting to consume material. White smoke can also indicate light and flashy fuels such as grass or twigs. Thick, black smoke indicates heavy fuels that are not being fully consumed.
A faulty or dirty spark plug could be the reason your lawn mower won`t stay running. It might produce the initial spark, but the spark won`t be enough to keep the engine running if the plug is clogged with dirt and oil. Spark plugs are usually located on the front of a push lawn mower and connected to a black cable.
If blue smoke is coming from your lawn mower, it typically means that your machine is burning excess oil. If you wait it out for 10-15 minutes, the blue smoke should soon dissipate. You probably just need to wait until the extra oil burns off.

Discover Relevant Questions and Answers for Your Specific Issue

the most relevant questions and answers related to your specific issue

Oil leaking too much from the oil filter and blowing out smoke
ANSWER : Kathy there is too much oil in the mower. Drain some out and try again.

Dont know what type of oil to use – Toro Power Lawn Mower
ANSWER : Put straight 30 weight motor oil in it. Not 10W30 or any multi-viscosity oil. Straight 30 weight motor oil. If you’re doing a complete oil change, then you may want to use Synthetic 30 weight, which will last longer between oil changes and also make your engine last longer (but it costs more too). Best of luck to you.James

YARD MACHINE MOWER NOT A YEAR OLD YET AND IT CRUDDIES UP EACH NEW SPARK PLUG AND SMOKES, NOT RUNNING WELL. ITS RUNS REAL FAST AND THEN REAL SLOW, SPUTTERS. I HAVE ALWAYS KEPT AIR FILTER CLEAN AND OIL CHANGED. WHAT COULD BE THE PROBLEM? MY SON THINKS ITS THE RINGS AND SAID I SHOULD TAKE IT BACK TO HOME DEPOT BUT I’VE HAD IT FOR 11 MONTHS. WHAT SHOULD i do??
ANSWER : Return the mower if possible for warranty repair or call MTD with the issue. MTD mowers typically are good quality and should run like new for a long time with proper care. Depot may give you a 1-800 number instead of customer service so before you load up the mower talk to them. It does sound like a bad valve seat or rings either one is not typical wear and tear.

I have a troy bilt riding mower. I put a new battery in it last summer. This yr., my son left the key in on positon when he got done cutting the grass. Naturally it killed the battery, I jump started the mower and cut grass for 4 hrs., but the battery did not charge. What could the problem be?
ANSWER : It may not be charging due to a bad connection to the battery or to the generator on the engine. The generator on the engine may be going or has gone bad.I hope this helps.

Blowing oil out of the engine – Toro 52" 27hp Z Master Zero Turn Lawn Mower
ANSWER : Check oil level fuel could have flooded through into the engine oil which will cause it to blow out if so clean out carby and check that needle in the carby is sealing

I have an early 90’s cub cadet rider and it was over filled with oil. Now it smokes and blows oil out the exhaust. Could over filling it cause this? If not are there any common causes of blowing oil
ANSWER : Yes, over filling can cause this. The fix for this is to put the oil level back to normal, and run your machine normally, until the oil residue burns back off. Some “side effects” may be fouling spark plugs and occasionally residue build up in the muffler, so, keep this in mind. Normally, though, everything goes back to normal. It’s better to run the machine for a while than starting and stopping it, to allow the machine to get up to operating temperature and clean out the exhaust system.
Best regards, –W/D– please feel free to rate this solution.

My craftsman lawn tractor smokes when I start it and it is blowing oil out. What is causing this?
ANSWER : Check the oil and see if it smells like gas the needle valves int he carb have had alot of problems seating and gas over flows into the crank case change the needle and seat and change the oil

Pouring out oil.
ANSWER : Where is it pouring out from? Might you be over filling the mower? Is your drain plug tight? the right thread? (meteric vs non-metric?) if the casting is cracked, you are done. The other items are probably correctable.