New Flyer Industries Ltd. (New Flyer) is recalling certain model year 2009-2012 C35LFR, 2008-2013 C40LF, 2008-2013 C40LFR, 2009 L40LFR, 2009 C35LF, 2013-2014 XN35, 2011-2014 XN40, and 2012-2014 XN60 buses, equipped with certain Cummins Westport ISL G engines. Excessive engine crankcase pressures may cause the 90-degree elbow of the vent tube assembly to detach from the crankcase ventilation breather, possibly allowing engine oil to come into contact with hot surfaces.