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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 26741
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a 12 hp Briggs & Stratton on my riding mower. Forgot

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I have a 12 hp Briggs & Stratton on my riding mower. Forgot to check the oil, ran it, and right as I was running out of gas while mowing the engine got loud. I shut it off and as the engine wound down there was a loud pop and white smoke came out the top and out of where the air intake is. Two days ago I topped up the oil, it started and i made a couple passes on the lawn but the power was real weak. I would stop, put the clutch in and it would rev up and get real loud, then when I engaged again it was so weak it was practically stalling out. It got so weak I just shut it off, then when I did I got the white smoke coming out again. The engine runs so hard and loud its deafening and I can feel it vibrating the whole mower. Is there any fix to this problem you might reccomend?

Curtis B. :

Welcome to JUST ANSWER small engines, let me try to help you !!

Curtis B. :

This is the older flat head design engine. You likely have damaged the piston and rings and the only help for ti would be to remove the piston, hone the cylinder to see if it will clean up. then replace the piston and rings with new parts.

Curtis B. :

The white smoke is oil bypassing the piston.

Customer:

I noticed some oil leaking out the bottom of the engine where it attaches to the mower too. This doesn't sound too good, kinda what i expected. I'm going to try and take a shot at fixing it tomorrow...Pretty pricey if I were to bring it in to a repair shop?

Curtis B. :

Is the mower worth putting the time and money in? Or is it time to replace it?

Curtis B. :

Mower shop repair would be expensive, figure 400 to 500 dollars.

Customer:

Time to replace I think. It was an older one..I got it off Craigslist for $300 & mowed my lawn perfectly it's first time. Then this haha.

Customer:

Ok, well thanks for the advice. I'll give it a shot taking it apart tomorrow but given this info, i wont set my hopes too high.

Curtis B. :

Put it back on Craig's list, you can get something for it, somebody will but it for a project!

Customer:

Good call!

Curtis B. :

Here is site with breakdown and parts

Curtis B. :

Here is site for specs.

Customer:

Nice..thank you. I appreciate you answering everything so fully. From what I googled online it sounded like running it without oil had caused permanent damage & it was time to buy a new one...but wanted to hear it from an expert before I think about spending $1k.

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