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LesH

Dirty Oil..............

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LesH
I have a 2 cylinder side shaft Briggs on a lawn tractor. It runs fine and is a grass cutter only, not run hard. The only question is that the oil gets real dirty, only after an hours worth of cutting. I use Valvoline SAE 30 and do not over fill. Engine does not burn oil. Air cleaner is a new paper fiklter style. Any ideas???

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rsnik
Les, The problem may be heat related. I bought a new Murray lawn tractor back in '96 with a 48" deck. It had a V twin 18.5 hp vertical Briggs. Even when new the oil would turn dark after one mowing in the summer. The engine was simply running too hot and "cooking" the oil. Granted I had 2/3 acre of lawn. I had to mow in the early morning or evening when it was cool. I also had to remove the tin on the engine and clean out any chaff and debris frequently to help the engine run cooler. What worked best was getting rid of the Murray and buying a Simplicity. :D

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perry
does the oil smell like gas ?. i have seen the fuel pump diaphrams go bad and the gas leaks back into the crank case. but usually it will start burning oil from the exhaust when the oil this out.

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BLT
Maybe the oil it doing its thing, lubricating and cleaning. The only way to know for sure is have the oil analyzed by your oil producer or an independent lab. It generally costs about $60 a pop. That will tell everything you wanted to know plus some stuff you didn't know. I have some engines that the oil turns dark after a few hours of running but consumes next to nothing. At least you don't have to squint on the dipstick to to see where the oil is.:)

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dhardin
It's one of two possibilities. Or a combination of the two. A) It may have or have had the cooling fins around the cylinder plugged with dust, Causing the rings to over heat. Not bad enough to weak in the top compression ring . But the bottom oil ring and center compression ring is weak. Check for excessive "blow by".If you have a lot of blow by you well may have found the problem. But the cause could be as mention or any number of reasons. B). 2 fold but the sane symptom. air filter or intake/carb is letting dirt get into the piston chamber. Hence wearing the rings and sidewall enough that the dirty oil could be very fine particles of dust sucked into the engine. OR) some one has not changed the oil on a regular bases or have not got all the old oil out when changing oil. This small amount of duty use oil left in the bottom of the pan over time will accumulate to slug/gunk. SO you change the oil and the first time you run it up to operating temp the gunk is totally contaminating the new oil. A good tip it to always change your oil after you mow. Not before. the hot oil will drain out the slug better. As well as when changing the oil open the drain and the get a jack and tilt the complete mower/tractor so the drain plug is on the low side. Hence getting ever ounce of old oil out of the bottom of the pan. Don't be in a hurry. Let it compliantly stop dripping. Aways change oil filter when changing the oil if equipped.

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