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Discussion Starter · #1 ·
i have a 12 hp powerbuilt engine that seem to put out oil vapors on the right side of the engine, it has 125 hours, oil has been changed twice a year, air filter cleaned and changed regularly, it is a 1996 year model. it was used to mow around a new house and there was lots of dust until the weeds and grass got growing. is there a crankcase vent that needs to be serviced? it doesnt appear to have blowby out the oil fill tube. my other equipment has 800 plus hours and dont do this but werent used in dusty conditions. any advice other than the motor was a poor choice? thanks
 

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Its entirely possible to have a bad or clogged breather assembly on this motor and it would put out vapors as described, but it could still be a slight amount of blow by from rings, or it could just be the normal vapors that this motor puts out. The craankcase breathers arte pretty cheap and easy to change. There is a disk and a spring, and its not uncommon for the disk to crack or get carbon or sludge or debris between it and the disks seat and allow more vapors than normal to pass out. There should also be a vent tube that hangs down from this breather assembly or it could be vented into your carb air cleaner assy. Usually has 2 bolts or screw that attach it to the block.
 

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I will agree with Chipmaker my old 8HP did the same thing i changed the breather and that fix it. If you change the oil regular and with only 125hrs it has to be the breather.
Jody
 

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If I recall correctly, there is small hole/holes in the bottom of the breather assembly and inside the block for oil drainage back into the crankcase that could be obstructed.

Mark
 

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Yep, your right about the hole that allows oil to return to the sump. Its possible as you say, that it could be obstructed. All the breathers I have seen are usually located by the valves and removing it allows access to the valve stems. I can't say with 100% accuracy, about a B & S but the breaters on a Tecumseh is possible to put it in the wrong way as its in two or three sections and i its installed wrong will have the little disk that acts like a check pulse valce to be be too low to the galleys bottom and it will most definately make lots of vapors. I ran into that with my Crapsman Agri Fab Vac cart as it was doing the same thing, lots of vapors out of the breather but ran fine otherwise. Turned the breather assembly around and it quit. About two hours later though is when it threw a rod, but thats totally unrealted. I chalked that up to it being a Crapsman Tecumseh engine.
 

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Discussion Starter · #6 ·
just to recap on my original post, added oil dye to engine and checked with a black light, noticed dye from the bottom side of the motor on the right side looking up through the mounting hole on the frame. i unbolted the motor and raised it up and a bolt fell out that wasnt vivible from the bottom. found out it held the sump to the block, locktited it in and checked the rest. small amounts of oil would leak onto the top side of the drive pulley but was not vivible from the bottom side and the crank seal was always dry. i cleaned everything off good and will have to mow about 10 hours to verify repair, just hope the gasket wasnt damaged but i think i am back in business. there goes my thoughts for something new that i cant really afford right now anyway.
 

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Loose crankcase bolts on Briggs vertical shaft engines are a common problem. Don't ask me why but single cylinder 28 cubic inch blocks ( various hp 10 & up) are very prone to this . Model number will start with a 28XXXX.
Crazy thing is we've had homeowner customers run them that are so loose oil is coming out everywhere and the oil sump is moving around while the engine runs ! Freaky.
Got a brand new lawn tractor on the floor leaks
 

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Discussion Starter · #8 ·
thanks for the heads up Neil, looks like i will be checking them for spring maintenance. too bad the one that fell out is under the mower housing and not accesible with out raising the motor up. at least i know what to look for when dust and clipping start to stick below the motor mounting area and the lower part of the hood.
 
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