Smoke coming out of intake

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I should have known something would happen. The other day I switched from Craftsman 30wt oil to Pennzoil YB 10W-40. It seems to run great. After 45 minutes of mowing I look and notice a very thin white smoke almost invisible, coming out of the intake/filter. I shut it down, and as it slows down it starts puffing much whiter. Like puffs of white smoke. If I pull the starter cord slowly it puffs out the intake and exhaust, white smoke. If it was coming out of the exhaust I could understand, but... Out of the intake? Is this some side effect of the oil? Or is the engine messed up? Its a Briggs 675 Flathead with a season and a half of use.
 
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Are you sure you didn't overfill it? Also, when you changed the oil did you by chance tilt the mower with the carb on the low side?
 

Nick R

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I might have tilted the mower that way, but mostly on the side with the oil drain down. It might be a little overfilled, but I don't understand how that would make it smoke out the intake.
 

JTK

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Check the routing of the crankcase breather hose, but what you describe is the symptoms of being overfull. It shouldn't have anything to do with that minimal viscosity change. Joel
 
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Originally Posted By: JTK
Check the routing of the crankcase breather hose, but what you describe is the symptoms of being overfull. It shouldn't have anything to do with that minimal viscosity change. Joel
x2
 
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I'm starting to wonder if it's something they're putting in the gas nowdays. I've been working on quite a few mowers over the last week and I never seen so much smoke. Fresh oil does seem to help but even with fresh oil the 98 year briggs I've used since 01 has never smoked (unless you count the time I ran straight rislone in the crankcase). Could be the E10 the gas station I use isn't marked either way.
 
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Check your air filter. I don't think it's the oil. A good carb cleaning could also be in order. Sounds like fuel mixture isn't burning proper. Restricted air flow can cause this problem.
 
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I have a Briggs/Stratton 11hp mower yesterday it started running with quite a lot of smoke from the carburetor and exhaust also oil coming back through the carb. Anyone had this issue or know how to fix it? I have rebuilt the carb. in my engine I am sure it is the rings not sure if iwant to tackle that job yet.
 
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Originally Posted By: dbdeland
I have a Briggs/Stratton 11hp mower yesterday it started running with quite a lot of smoke from the carburetor and exhaust also oil coming back through the carb. Anyone had this issue or know how to fix it? I have rebuilt the carb. in my engine I am sure it is the rings not sure if iwant to tackle that job yet.
Check the oil level..you may have put to much oil in it. Or have tipped the engine to far.
 
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Warstud, I have done all of that. It is a riding mower and was not tipped a mower shop informed me to rebuild the carb. an it would solve the issue but after doing that the problem is still there oil level is just below the full line.
 

JTK

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Originally Posted By: dbdeland
Warstud, I have done all of that. It is a riding mower and was not tipped a mower shop informed me to rebuild the carb. an it would solve the issue but after doing that the problem is still there oil level is just below the full line.
I don't understand how a carb rebuild would rectify a crankcase pressure/blowby issue. Provided this is a flat head 11hp, I would check the breather assembly down on the side of the block. The separator element and reed in there might need a good cleaning. Joel
 
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JTK, Thanks for your reply but I replaced breather assembly when I rebuilt the carb. The reason the carb was rebuilt a mower repair shop informed me to do it I did not see how it would solve the oil issue but It need the rebuild anyway just trying to keep from installing new rings. Daryl
 
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JTK

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Daryl, did you do a compression check on this beast? Does it start easily and run real strong aside from the smoke? If it's just starting to loose some compression you could try a 15w40 or a 50wt engine oil to see if that seals her up some. Joel
 
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JTK, No I did not do a compression check it starts very easy and runs good.I have some 50wt oil I will give it a try again thanks for you help. Daryl
 
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I would use a HDEO Delo400 40w or even Delo400 30w over the Pennzoil 10w-40. From experience long term given temp conditions ranging from 72 F - 88 F...I've had experience with the Delo400 10w-30 that oil was like water long term..I believe it was out after 10 hours and the first and last time I would use any multigrade 10w-XXX. My opinion of course.
 
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Have a friend with an OHV 17.5 Single Cyl. Briggs. Just the other day it started running rough and puking oil back through the carb. Plug appeared to be burning correct. THe problem is the engine will run under load for 30 min then stop. Not sure on oil grade. He did change maybe put wrong oil in. Mower was on the side for a lil while, (belt change) any ideas? I am stumped.
 
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