Briggs 18.5 OHV mower smokes when mower is engaged

Big T

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  • / Briggs 18.5 OHV mower smokes when mower is engaged
Got a 9 year old Craftsman 42" cut mower with a Briggs 18.5 Intek OHV engine. Just started smoking when the mower deck is engaged. Runs fine otherwise with no smoking. When the mower deck is engaged and engine is at full throttle, it leaks oil from the breather in the fuel pump and smokes from the muffler. When you open the air breather, smoke comes out of there, and out of the oil fill unit when you take the cap off. However, none of this happens when the deck is not running. So the extra torque needed to run the deck is causing some type of issue in the engine. We've had the carb cleaned and it still does this. The air breather is brand new and spotless. I'm not an engine guy, so I have no idea what might be causing this. Any idea what the problem might be? I was told that it might be a bad ring on the piston? Engine shot?
 

ohioboy15

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  • / Briggs 18.5 OHV mower smokes when mower is engaged
Yep bad ring/s just use thicker oil. Same thing happened to mine. Upgraded to 5w-30 which is the thickest i can buy locally and its stopped its smoking after a few runs :)
 

Big T

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  • / Briggs 18.5 OHV mower smokes when mower is engaged
Thanks for the tip! Question though. If it is a bad ring, does that mean the engine is on it's last legs and the thicker oil will just get me by until it eventually blows. Or will the thicker oil keep it running for the foreseeable future? We have about 2 acres to mow, so it gets put through its paces. But I've always been good about changing oil and filters several times each summer. Do you think going with 5W-30 will get me by for a while, or is just a temporary bandage and I'll eventually need a new engine or mower? Thanks so much for the help!
 

ohioboy15

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  • / Briggs 18.5 OHV mower smokes when mower is engaged
Well hard to say, i have bad rings in mine and it burned through normal oil so fast and smoked so much it choked everyone in the neighborhood(that bad like a firework show ;) ) so since i started using 5W-30 its been so much better, only get a few times here and there where it will smoke for a few minuets then stop. This has been for almost 2 years now and i cut the grass 3 times a week and i have almost half an acre so you should replace the ring if you have the skills but if you dont(i dont thats why i havn't yet) then this will hold you over for a nice amount of time.
 

panabiker

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  • / Briggs 18.5 OHV mower smokes when mower is engaged
Yep bad ring/s just use thicker oil. Same thing happened to mine. Upgraded to 5w-30 which is the thickest i can buy locally and its stopped its smoking after a few runs :)

I though the larger the number, the thicker the oil. Wouldn't 10W-40, which is common, be thick than 5W-30?
 

Big T

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  • / Briggs 18.5 OHV mower smokes when mower is engaged
I thought the same thing. Other blogs have mentioned using 15W20, or going to a 40 weight, such as 15W40, or straight 40HD. One guy said all the landscape companies in his town run straight 40HD in all their mowers. The idea is that the thicker the oil, the more film it puts around the rings to prevent the oil burning. Any thoughts?
 

Lawnranger

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  • / Briggs 18.5 OHV mower smokes when mower is engaged
I though the larger the number, the thicker the oil. Wouldn't 10W-40, which is common, be thick than 5W-30?

Yes, 10W40 has a higher viscosity compared to 5W30. 20W50 is even higher but that viscosity is to be used in engines that are designed and built to tolerances that will handle a higher viscosity oil.

This is my opinion only but using a higher viscosity oil to cover up a "usage" problem is like putting a Band-aid on an axe wound.

No harm in trying, though, as the damage has already been done.
 

Rivets

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  • / Briggs 18.5 OHV mower smokes when mower is engaged
I would take a look at the possibility of a bad head gasket and not bad rings. With the engine running at half throttle, unscrew the dipstick and set it loose on the tube. Does it jump up/down? If the answer is yes, replace the head gasket.
 
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