Oil leaking from exhaust

[Mowerdawg]

Prior to all this, was it using oil extensively? Had you added any just prior to this happening?
and he's right, exhaust seal......no fun...I'd rather unbolt the blade and engine and replace with a good on off a 25 dollar mower.....but that's me........

Oh, and seafoam or lucas fuel injector cleaner has been the best fuel stabilizer and all around additive i've used.....

 

[Briggs92]

Briggs does use valve seals on some models. You need the model and type of the engine and can look up diagrams on partstree.com

 

[Street Lethal]

I noticed this very thing when my flathead Briggs & Stratton engine was leaking oil from the muffler. Figured I was working on Chevy engines for so long might as well open up the lawnmower and give it an inspection. Pulled the cylinder head off, and immediately noticed that oil was leaking out of the exhaust valve when I turned the engine by hand. First thing I thought of was the exhaust valve seal might be bad. I removed the exhaust valve and immediately noticed that it didn't even have one, only the intake valve has a seal. So then I thought, hmm, maybe the valve guide is worn out, so I knocked out the old valve guide and reamed in a new valve guide, but when I installed the valve/spring and retainer back in oil was still leaking out of the exhaust valve when turned by hand...

Now, through all of this a great deal of oil was leaking out of the engine which of course needed to be replaced. I buttoned everything back up, stood the engine upright, then checked the dipstick to see how much oil was lost. In shock, the dipstick was still full, in fact, the oil was reading over the necessary requirement. Long story short, just as Kenny said in an earlier post, fuel was leaking into the crankcase, which would also explain why the fuel consumption was so great as I was only able to cut a limited amount of grass on just one tank. So, I drained the oil, replaced it with some fresh oil, and rebuilt the carburetor. Problem solved... :thumbsup:

 

[steverus]

I have an old MTD push mower with a Briggs 3.5 hp motor that I use at the camp. Hasn't been used in a couple months and noticed today the the could not pull the rope to start. when I turn the blade by hand it goes real hard and oil comes out of the exhaust. I noticed that the oil level is just over full. Any suggestions

 

[KennyV]

WELCOME to LMF...
Drain the oil, it is mostly gasoline anyway...
Remove the spark plug, turn the engine over a few times to blow out the oil, clean up the plug...
Then you will likely need to clean up the carb and check the float & needle seat... that's where the fuel should be turned off when the bowl is full... they can seep past & over time flood into the carb and down into the crankcase with the oil..... causing your problem..
To prevent this from happening in the future.. install an inline fuel shut off valve between the tank & carb... something like this: BRIGGS/DEERE/TORO FUEL SHUTOFF VALVE #494768 / #AM107340 / #54-3150 ~~NEW~~ | eBay
You can find them everywhere... :smile:KennyV

 

[Carscw]

And do not let the plug wire rest in front of the plug hole. Don't tell any one but I have done this and had to put out a fire

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