Engine Burning Oil

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  #1  
Old 08-05-02, 09:42 PM
garyv
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Angry Engine Burning Oil

I have a White lawn tractor with a Briggs and Stratton Engine that has a pressurized filtration system. Similar to a previous posting - my engine also burns oil after a few minutes of use. The oil is coming from the breather tube that is locating within the air cleaner. I have also noticed some smoke coming from the dipstick when it is removed. Other than the smoke, the engine runs fine when idling and some light driving. I have checked the oil level and its low, I have also changed the air filter. I was considering changing the breather element ( Is this considered the PCV valve? ) but was not sure if that would help my problem? The motor is only 4 years old - any suggestions?
 
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Old 08-05-02, 09:51 PM
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If the smoke is coming from the pcv tube, then the valve is probably OK. How old is this mower, more importantly...how much use has it seen? It sounds from your description like your rings are bad. Is the engine a 2 cylinder? Vanguard, or just twin?
 
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Old 08-06-02, 02:46 PM
garyv
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The specifics on the engine are as follows:

-16Hp OHV, 1 cylinder, Pressurize Filtration
- Model#: 31777
- Type: 0120-E1

The engine only has a 3.5 years of use; however I do have a moderate hill and a sloping lot to cut.

Is the PCV supposed to allow both oil and Air to vent from the CrankCase? When the engine is idling, I have noticed with the air cleaner off, the PCV tube is puffing a lightly smokey mixture.

I do believe the oil is coming from the PCV tube because the Air fillter case has oil splashes on it and the intake snorkel has puddles of oil in it. If you have bad rings does the oil enter the cylinder around the rings? Or could it force the oil through the PCV valve.

If it is the cylinder rings - would the engine run poorly?
Is there a test I could perform to evaluate my piston rings?
 
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Old 08-07-02, 10:28 PM
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Hello garyv!

The PCV valve (Positive Crankcase Ventilation valve) allows the crankcase of the engine to vent pressure created by the back and forth motion of the piston, and combustion gasses that escape past the rings. This venting air should only be air. The engine squeezes air with the piston. The rings make a seal around this piston. When they begin to wear, they don't seal as well, and this "squeezed" air leaks past them into the crankcase. This creates more pressure in the crankcase and it must escape through the PCV valve. When such a high volume of air begins to flow through the valve, it carries oil from the engine with it. (more than the PCV valve can catch and drain back into the engine). This oil goes into the intake and gets burned causing smoke.

Also, There is one ring that is intended to scrape the excess oil off of the cylinder walls. This is the oil ring. If it wears too much, oil will not be removed from the cyl. walls as intended. This extra oil gets into the combustion chamber with the fuel and air, and gets burned during combustion. This also causes smoke, but not so much oil in the breather. For your breather to be filling with oil, the compression rings are most likely worn, and probably the oil ring too. A compression test done properly will tell you if your rings are bad. Rings normally won't cause it to run too badly until they get pretty bad.

Another thing...now that we know what engine you have, and it is an overhead valve engine, you may also check the head gasket. If it blows between the cylinder and push-rod chamber, it will smoke and blow oil through the PCV valve. If you don't have lots of hours on this engine, and it has been well maintained, then I would tend to think this is your problem rather than rings.

I hope this helps! Let us know how it goes!
 
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