Holy S**t, this looks serious, no need to panic, blue smoke after an oil change is common, and usually, the fix is simple.
The most common reasons ATV’s smoke after an oil change is oil spilled on hot components and too much oil.
In this post, you’ll learn why an ATV smokes after an oil change and what you can do to fix it right now.
ATV smoke after an oil change usually fixes itself. Accidentally spilling some oil close to the exhaust will cause smoke as the exhaust heats up. When the heat burns off spilled oil, the smoke will stop and the problem solved. Similarly, jacking up your ATV to change the oil may cause oil to enter the cylinder. This, too, is a self-fixing issue and should burn off quickly.
If, however, the smoke doesn’t clear after ten minutes, shut down the machine and begin your investigation by checking the oil level.
ATV Oil Change
Changing the oil is, as you already know, super important. The oil helps cool as well as lubricate the internal components. The filter collects all the micro filings caused by natural engine wear and tear.
The filings, if allowed to roam freely inside the engine, would act like an abrasive prematurely wearing out internal engine components like crankshaft & camshaft bearings.
Oil quality is extremely important, but so too is quantity. Everyone knows too little oil in a motor spells trouble, but what about too much?
Excessive oil could damage your engine, but no oil definitely will. So, while too much oil is bad for your motor, it’s rarely terminal.
The moving parts inside the engine need room to move. The piston, crankshaft, and other components create pressure inside the engine as they move. (Known as crankcase pressure)
A crankcase is only partially filled with oil for this reason. The void allows room for positive and negative pressure. When this void is filled with oil, it causes excessive crank pressure, and oil is forced to move into places it shouldn’t.
What Causes The Smoke
Too much oil in an ATV engine has to go somewhere. The oil has no choice. The forces of the crank pressure are too great. The excessive oil often causes crankcase gaskets to fail and leak oil onto the ground.
Oil may also be sucked up into the carburetor via the breather assembly and ingested by the engine, which causes dramatic-looking blue smoke.
Oil can make its way past the piston rings and into the combustion chamber. This, too, results in blue smoke. In addition, excessive oil inside the chamber may be expelled into the hot exhaust system, causing even more blue smoke.
Fix The Smoking
This is usually an easy problem to solve. Allow the engine to cool and park on level ground; check the oil level carefully. Expect to see a reading that’s way over the full mark.
Some dipsticks need to thread all the way home until they seat to get a correct reading, and some don’t. Check your model’s procedure.
If it’s a case of too much, you can remove the excess oil using a siphon or drop some out of the bung. If you choose to drain the oil, don’t be tempted to keep it for top-ups. Crap from the underside can fall into the oil catch, contaminating the oil.
Oil Level Isn’t Too Full
If you’ve checked your oil level and it’s perfect. There are a couple of other likely problems to check, they include:
- Head gasket failure
- Incorrect oil type
1 Cylinder head gasket failure
Depending on your style engine and where the gasket fails.
A failed head gasket can cause oil to enter the combustion chamber, and that means smoke. The only fix here is to replace the gasket.
What’s a head gasket? It’s a heat-resistant graphite gasket that’s sandwiched between the cylinder head and the cylinder. Its function is to seal the combustion chamber. Head gaskets wear out, and gaskets are a pretty common failure.
But why would it fail after an oil change? Yea, it’s a fair question. I have had this happen twice in my wrenching career, and my thoughts are along these lines. I believe fresh oil, an already weak gasket, and blow-by are to blame.
What’s blow-by? Compression that escapes past the piston rings is blow-by. It happens naturally as the engine wears. Unscrewing the dipstick and watching its movement as an engine idles is a very loose gauge of how much blow-by a motor has.
Fresh oil is heavier and does a better job sealing leaking compression past the rings. Reduced blow-by ordinarily would be a good thing. However, with fresh oil, the now increased combustion chamber compression blows out an already weak spot in the head gasket.
The now damaged gasket allows oil into the cylinder as the piston moves down the bore. Oil in-cylinder equals smoke.
If you suspect a head gasket issue, run a leakdown test to confirm.
To perform a leak down test you’ll need test kit and a compressor. Fill the combustion chamber with compressed air and check for leaks.
2 Wrong Oil Type
The oil type specified by your engine maker is important. Engines are designed with specified tolerences, and clearances, oil weight (oil grade) is factored into these specifications. Using a thinner oil than specified If your machine requires mineral oil and you use a lighter semi or fully synthetic, you may notice the smoke.
This isn’t necessarily a problem with your engine. The tolerances of your piston rings may not be compatible with the much lighter oil type.
You’ll find the tools I recommend here on the ATV tools page and you’ll find common spare parts here on the ATV parts page.
You may find these posts helpful:
How often should I service ATV?
Will the bike start without oil?
Oil taking from the drain plug
- About the Author
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John Cunningham is a technical writer here at ATVfixed.com. He’s a Red Seal Qualified Service Technician with over twenty-five years experience. He’s worked on all types of mechanical equipment, from cars and trucks to ATVs and Dirt bikes.