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Discussion Starter · #1 ·
I have a briggs...18 hp twin...it has two valve covers...one for each cylinder...both hoses go to the air cleaner or breather....one is producing some oil...the other is dry...what does it mean??...are the valve seals bad on this cylinder??....is this what is called blowby..or blowback..in a car??...could the piston or rings be worn on this side?..would that produce oil just on one side??...

I know that under the valve cover..are both vavle stems...valve springs...seals..and there is a hole that goes to the crankcase I think...could oil come up that hole?..or is it coming past the valve seals?

give me your ideas.. thanks!..
 

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How long has it been since the air filter was replaced. I have seen this a few times lately. The filter gets a little dirty and it starts pulling oil through the hoses.
 

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Discussion Starter · #3 ·
well..it does it even with the air dliter removed...but only through one hose...the other hose from the other valve cover doesnt produce any oil...and the tractror isnt smoking...if it were blow by...from a worn ring or piston...would it push oil up both hoses?..or just one?..could it be a valve seal?...or a blown head gasket??..let me know your thinking..

thanks
 

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Blowby woud pressurize the entire crankcase, and you'd probably get oil from both hoses. I'd pull the valve cover and make sure that any baffles are still in place.
Also, perhaps the other hose or valve cover is clogged - can you blow through the "dry" hose into the crankcase?
Do you mow on a slope so that one side is lower than the other?
Perhaps the other hose is sloped enough so the oil runs back into the valve cover.
Just a few random thoughts...
 

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Discussion Starter · #5 ·
Hey Fcubman..thanks for the advice..I will pull the vavle cover..is there some kind of air valve under there?...well..I am pleased you do not think its blow by....I think your right..seems like blow by would come out of both covers..i will pull the valve covers and let you know what I find out..thanks
 

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I doubt that there's a valve in the cover - probably just a baffle or two, no moving parts. It is odd that only one hose is "bleeding".
 

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Discussion Starter · #7 ·
the other hose is open..and air flows through it..but no oil...I checked the compression..and its good..about 115 each side...can the compression be good and still allow blowby??...could a valve seal do this?...or a leaking valve or head gasket?..I am racking my brain..but nothing makes sense to me...I must be missing something...
 
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