Editing Wankel engine (section)

===Sealing===
Early engine designs had a high incidence of sealing loss, both between the rotor and the housing and also between the various pieces making up the housing. Also, in earlier model Wankel engines, carbon particles could become trapped between the seal and the casing, jamming the engine and requiring a partial rebuild. It was common for very early Mazda engines to require rebuilding after {{convert|50,000|mi|km}}. Further sealing problems arose from the uneven thermal distribution within the housings causing distortion and loss of sealing and compression. This thermal distortion also caused uneven wear between the apex seal and the rotor housing, evident on higher mileage engines.{{Citation needed|date=December 2010}} The problem was exacerbated when the engine was stressed before reaching [[operating temperature]]. However, Mazda Wankel engines solved these initial problems. Current engines have nearly 100 seal-related parts.<ref name="JhYt4Sa"/>

The problem of clearance for hot rotor apexes passing between the axially closer side housings in the cooler intake lobe areas was dealt with by using an axial rotor pilot radially inboard of the oils seals, plus improved inertia oil cooling of the rotor interior (C-W {{patent|US|3261542}}, C. Jones, 5/8/63, {{patent|US|3176915}}, M. Bentele, C. Jones. A.H. Raye. 7/2/62), and slightly "crowned" apex seals (different height in the center and in the extremes of seal).<ref>Kenichi Yamamoto, Rotary Engine 1981, Page 50</ref>