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GWGAllisfan

23D smoking

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GWGAllisfan
I'm having a smoking problem with my FDT landlord, with the 23d engine. Recently, since Murphy came to visit the engine on the 7112, and the driveshaft on the 712, this old landlord has become my mowing tractor. The first time I mowed the yard all was fine, so the second time, all I did was check the oil, adding some, possible a bit much since the tractor wasn't on perfectly level ground. Late in the 2 hours of that mowing the tractor started smoking, but not out of the exhaust. I finished that time and cleaned up the oil on the block and around the engine faceplate, and thought I'd try again and see where the oil was coming from. Last night, I made sure the engine was level, checked the oil, and it was right at the run out level in the plug, like it should be. From the start the engine smoked, again not out of the exhaust, but more like at the spot where the fins of the cylinder meet the crankcase, and even from the underside of the points box. I considered that it might be a bad breather, so I removed that ( this is the one that is under the S/G on the right side, not the one on the valve cover like later motors) and cleaned it out with brake cleaner, put it back and same thing happened. There is no smoke visible from the exhaust, the plug is dry and light coloured, engine runs good except it seems to labor a bit more when it smokes, but that could also be that is the heavier grass, too. Any ideas? maybe still too full of oil? Maybe blowby pressurizing the crankcase?

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dentwizz
The 23D breather has no ability to valve the flow, so what you get out the breather is directly related to combustion blow-by. It is sometimes hard to gage where it comes from because the routing is into the cooling air path. If the oil is set to the factory level and the rings are not perfectly sealing(a long way from 'bad') it will smoke some initially. A minor mix variation could fix it, or simply a heavier grade of oil(I sometimes ran 15-40w or 30w on mine when it still had a 23D). The ring gaps can sometimes 'line up' with these producing a temporary increase in blowby until they re-skew themselves out of line. Are you running it at half/full throttle or staying low? Higher throttle is a bit better at using up the smoke oil and keeping the temp a little higher at the plug.

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GWGAllisfan
so all that together sounds like it's just vapourising excess oil in the crankcase and pulling (or pushing)it out the breather. The spot the oil seems to come from is right where the breather tube ends under the cover. I try to run at nearly full throttle, but I have to watch for the throttle control to vibrate back closed. It seems to smoke more at high speed, of course at high speed there would be more crankcase pressure. The exhaust is dry. There is no oily residue in the muffler. Sounds like I just need to watch the oil level carefully and run it some more.

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