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Step Wear on Irons

Old 07-31-18, 01:28 PM
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Step Wear on Irons

I'm pretty sure this iron is not reusable but I'm wondering what can cause this much of a step on the irons? Motor is an S4 13BT.
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Old 07-31-18, 06:31 PM
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Step wear on the side housings is due to insufficient air filtration. Dust gets between the oil rings and side seals on the side of the rotor and has no way back out, so you end up with lapping paste instead of lubrication.

I cringe when I see people running with NO air filter, let alone with any vacuum leaks! Having no air filter is a quick death for a rotary.
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Old 08-01-18, 03:21 PM
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iSeems like a good bet that this iron has been lapped previously, removing the nitrude layer. Curious, if you know how many miles on that rebuild?
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Old 08-07-18, 12:35 AM
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I might not too sure on the mileage the previous owner said just a few thousand miles. I bought it mainly for the housings.
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Old 08-12-18, 05:42 AM
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I usually don't worry about the vertical line at the spark plugs, that is going to be there on any engine that has run any real length of time because that is where chamber pressure is highest, and the rotor is moving the side seal in a slicing motion there rather than a sweeping motion.

However when I see something that I call delta wear, I prefer not to use that side housing anymore.



See the curved line that is tangential to the main wear groove that sweeps inwards across the oil seal tracks? That is the side seal wearing the surface in a sweeping motion. That line will also always be there if you look real closely, but if it has a hard edge that can catch a fingernail, it's time to replace, or have the housing ground and re-Nitrided. By the time you have this much wear, that vertical line is generally through the factory Nitriding, as is the very peak of the delta in bad cases.
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Old 08-12-18, 05:49 AM
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Forum software is broken and won't let me edit. Sorry for the huge image, I didn't think it was that large.

There is a secondary reason why that delta wear is bad, besides forcing the side seals to have to flex and follow an irregular surface. It won't have to cross that line, after all the line is the definition of its boundaries, the seal only has to deal with the surface not being perfectly flat. However the oil control rings DO have to cross that line, and they will die a very rapid death if forced to do so. Soon you have an oilburner on your hands.
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