Date of Award


Publication Type

Master Thesis

Degree Name



Mechanical, Automotive, and Materials Engineering


Engineering, Automotive




Six ball plugs were used to seal the oil lines in Jaguar cylinder heads using the press-fit process. The balls were made out of the 7075 Al alloy and were produced by forging, whereas the heads were made from the 319 Al alloy and were low pressure cast at the Essex Aluminum Plant (EAP), and machined at the Cleveland Engine Plant (CEP). The ball plugs were inserted at the CEP. Leaking was observed through the ball plugs during the CEP engine quality control operation. An investigation was launched to determine and eliminate the cause of the leaks. In order to isolate the main leak culprits, tests were subdivided into sections, which included: the heat treatment parameters applied to the 319 Al cylinder heads; metallurgical and geometrical characterization of the ball plug including: ball and casting microstructural analysis, hardness and homogeneity analysis, casting scratch and compression tests, characterization of the ball/casting hole wall interface, ball plug insertion and pressure tightness tests, effect of the insertion speed, ball lubrication and casting microhardness on the insertion force; geometrical investigation of the cylinder head boss design; leak mechanisms SEM/EDS investigation, as well as the Finite Element Analysis of the stress distribution in the ball and cylinder plug systems. As a result of these studies it was recommended that the cylindrical plugs should replace the ball plugs. CEP acted on this recommendation by replacing the ball plugs with the cylindrical plugs at 4 of the 6 plug locations where the leaks occurred most frequently. Source: Masters Abstracts International, Volume: 44-01, page: 0428. Thesis (M.A.Sc.)--University of Windsor (Canada), 2001.