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B112_son

Briggs 12 hp from B112

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B112_son

The original 12 hp Briggs in my B112 started smoking, very badly on start up but then clears up. I moved it from my shed to the garage yesterday so I could try to start working on it. Today I went out and there was a pretty large spot of oil that had apparently leaked. This was on the exhaust side of the motor. A little inspection and it appears oil is coming out from the engine around the breather tube. So does the means the rings are so worn I'm getting that much blow by?

Anything else I can check that may be an 'easy' fix?

My dad has had this since new and the engine has never been touched.

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B112_son

Thanks for the quick reply. That's what I was afraid of. Hopefully I can get through winter. I know I really won't know till it gets torn into but is it possible to just re-ring and have good results. Or would you recommend a complete overhaul?

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B112_son

This is weird. Has anyone heard of the carb sucking oil out through the breather? My dad was talking to someone explaining the problem and he suggested the carb. I thought he was crazy, except this fall I changed the carb out with another of unknown condition. Since then I rebuilt the original carb but didn't bother changing it out because it was running fine. I took the air filter off and the carb was sitting full of oil. So I changed the carbs out and so far so good. No smoking, and I left the filter off to see if oil was coming through the breather and none so far.

Has anyone ever heard of this?

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MikeES

If you have excessive blow by from your rings, your breather has a difficult time expelling all the gasses. With that volume of gasses and if your breather needs some attention you will get a lot of oil carry over/out of the breather and into the carb. Like stated above a plugged air cleaner will lower the pressure in the carb and create even more suction on the breather.

Now if your breather is bad and not sealing off the crankcase from excess low pressure (suction from carb) you will suck oil out of the crankcase into the carb.

I have a Kohler twin that DOES have a lot of blow by, it was sucking a lot of oil into the carb with the exact same symptoms as your Briggs. I disconnected the breather hose from the carb and vented it to air. No more blue smoke and no more oil consumption. So this tells me that my oil rings are fine and not allowing excess oil on the cylinder walls. I have fair compression (110 psi), but I must have compression ring leakage. A trick I learned on this web site is to clamp a rubber glove oil fill or dip stick (cap or stick removed) and start the engine and see if you quickly start filling the glove with gasses... if so a bad breather or excess blow by more than the breather can handle.

Check the breather first. Make sure the oil separator screen is still in place to separate the oil mist from the gasses.

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B112_son

Thanks for all the help. The air filter was in good clean shape. And it's only about a year old. When I changed the carb in the fall I put a brand new breather tube on. I replaced the breather tube because the old one was so hard I could not get it in the holes. Come to find out my dad had been running it this way for years without the breather hooked up. So when I replaced the carb and put the new breather tube on it was the first time the breather had hooked up. So Mike, it sounds like maybe a very similar situation to your Koehler. I haven't had a chance to work the engine as we have no snow or anything. It sounds like I need to do the rubber glove test and, if the problem continues, maybe unhook the breather tube again.

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chip61

I had a vertical shaft with a bad breather. It would allow so much oil into the carb it would choke the engine out. I replaced the breather and haven't had any more trouble-that was 5-6 years ago.

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MrSteele

The crankcase breather stopped up has made me a decent amount of money, now I do it for free. The breather stopped up has made a lot of engines to be scrapped because of the smoking problem. Most folks simply throw the engines away and get new ones. Clean your breather by soaking in solvent to loosen build up inside. Shake it til you can hear it rattle, then blow it out and simply put it back on. The stopped up breather is an indicator, though, of ring failure. Oily carbon will not get there if the rings were in good shape. Cleaning the breather is easy, and I have been known to do that several times before going to the effort of new rings. The older engines with the foam or bristle breathers did not have the problem of stopping up as easily, but they did it too. Same job..soak, blow it out, put it back on

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B112_son

It's been a while but I have an update. Rebuilt original carb and brand new breather hooked up I worked the engine hard over the weekend with a lawn roler. No smoke and no oil going through the breather. I have not done the rubber glove test and I probably need to do a compression test but for now it is running as good as it has in a long time.

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