Foley Develops a High Tech Rear Seal Kit. In response to customer input about leaky rear seals on Perkins 4108s, Westerbeke 40s and other engines, Foley now offers a replacement rear seal kit that will go a long way toward minimizing leaks. This braided, teflon coated graphite rear seal kit is superior to the original factory seal and comes with knife and installation instructions. Please call Foley Customer Service for more information.