Blowing white smoke saber B&S 28n707-1135-e1


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Old 04-17-12, 08:22 PM
J
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Blowing white smoke saber B&S 28n707-1135-e1

I was running the mower, turned it off when I restarted it, the motor blew a huge cloud white or light grey smoke and eventually stalled. I was able to restart it after a few days but very quickly it began blowing smoke again. The engine runs smoothly so I think it's a carb problem. Oil is fresh and at level.

I pulled the new air filter and there was a lot of fuel in the top.

Any suggestions. I don't mind messing with the carb but only if I need to.

Jim
 
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Old 04-17-12, 09:25 PM
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Sounds to me like the head gasket is blown, allowing combustion gasses to pressurize the crankcase.
 
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Old 04-18-12, 11:15 AM
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Shouldn't the crankcase breather relive the pressure? I assume the head gasket is an easy repair. Is the gasket a common failure on a B&S. Never had one blown on any of my equipment in my whole life (60 years)
 
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Old 04-18-12, 09:24 PM
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Yeah, the crankcase breather relieves it, along with all the vaporized oil that goes with the large quantity of air, straight into the air filter through the breather hose, causing the smoke. Yes, it's common on these briggs OHV engines. Yes, it's an easy repair.

If you hadn't said the oil level was correct and the oil was fresh, I would have asked if the oil was too high and if it smelled like gas.
 
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Old 04-27-12, 09:53 AM
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It was a leaking needle valve

When I pulled the valve cover it was flooded and the oil level was high. It turns out I have a very slow leak in needle valve in the carb and this causes the engine to flood. The lazy easy fix was to add a shut off to the gas line, dump the oil and dry out the engine and replace the oil.

It now runs great but if I forget to turn off the gas I'll be right back where I started.
 
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Old 04-27-12, 10:20 AM
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Well, that was my original thought, but you said you checked the oil level and it was fine and the oil was fresh.

I suggest fixing the problem before it gets worse. If there is water and rust in the carb, you may be able to fix it now, but if you leave it there and rely on that shutoff valve, you may wind up having to replace the carburetor.
 
 

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