# briggs stratton 20 hp mower engine



## wingman92

I HAVE A 20HP RIDING TRACTOR MOWER WITH A BRIGGS ENGINE .My Problem Is A Strange One. I Started The Mower Up And It Ran About 5 Min Before It Started Smoking Like A Locomotive, Smoke Was Blue Looking. I Turned Motor Off And Foung That About A Gallon Of The Gas Had Been Sucked Into The Crankcase. Anyone Know What Could Cause This? :


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## StaticInMyHead

Sounds like a cracked block to me. The only conclusion for that: trash it. It's probably useless now.


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## wingman92

thanks static, today i talked with a small engine stm who wants me to bring the carb to him tomorrow,we work at the same plant, he says the pump diaphram could fael and the gas could drain into the block thru the vac hose. im not sure, but im taking it to him tomorrow. i sure hate to give up on this mower engine, it cuts soooo good.


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## johnwill

I tend to agree that I'd look closer at other causes, I had a similar but less severe case with my snowblower, a new carb fixed it right up. :smile:


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## batty_professor

It was blowing blue due to the crankcase being so overfilled. The carburetor may have a problem, and that may have been caused by dirty gas supply. A new needle & seat should fix along with a new fuel filter. As a preventative measure, I must suggest getting in the habit of using the fuel shutoff petcock, it's there for that reason. You should also see this echoed in the user manual. Fix the fuel/carb problem, and change the oil, should be good to go. The worst thing about something like this is the explosion hazard. If you ran it to operating temperature it could have been a bomb.
The "pump diaphragm" you co-worker mentioned is not part of the carburetor. That would be part of a mechanical fuel pump, if the engine is so equipped. Those are usually not used unless the fuel tank is in a position where it will not gravity-flow to the carb.


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## JamesO

Some of the higher HP lawn tractors have a vacuum powered fuel pump. May tie into the crankcase somehow??? I have not looked to closely on these.

Trace the fuel line back from the carb, other than a fuel filter, you should maybe find this vacuum type of fuel pump. Rectangle about 1.5" x 2" with fuel line in and out and a vacuum line. If the fuel pump diaphram is leaking this could possibly fill the crankcase with fuel. 

If the mower was running fine until you saw smoke, it may not be a float level issue with the carb, could be a fuel pump issue.

JamesO


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## wingman92

thanks for the info ppl, we dissected the carb today and couldnt find a problem with it, its a carb with the diaphram on the side of it(briggs p/n 692815), I'll be off work tomorrow and am going to find a rebuild kit at the least.oh yea batty, i am also going to put a fuel shutoff in the line, that realization of the gasoline in the crankcase made me step back a few steps and wait til it cooled off before i drained that gas/oil mix out. Hope to report good news back here mon or tues. thanks


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## daniel432

i need to know how to set the timing on a 1996 20.5horsepower briggsandstratton engine


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