assembly. Until the cylinder head casting was redesigned some time in 1998, some vehicles would require this repair more than once, and replacement cylinder heads could develop the same crack. It was estimated that between 2% and 5% of SOHC Saturn S-Series vehicles were affected by this defect. DOHC engines had a different cylinder head, and did not suffer the same issue. DOHC LL0 The DOHC cylinder head had 16 valves and was made of lost foam cast aluminium. The camshafts were held in the cylinder head with bearing caps and driven by a chain off the front crankshaft sprocket. Motion from the camshafts was transmitted to the 16 valves by direct-acting hydraulic lifters. LL0 cylinder heads were changed slightly in 1995, when Saturn adopted electronic, linear EGR mechanisms, over the previous vacuum actuated design. The head casting was changed to accommodate different mounting surface of the new valve. All LL0 engines used MPFI and were rated at at 6000 rpm and at 4800 rpm. The DOHC engine was available on the upper-level model S-series vehicles (SC2, SL2, SW2). A revision of the LL0 appeared in 1999 and used a roller camshaft with hydraulic lifters and rocker arms, but power was unchanged. Also for 1999 provisions for a new air injection reaction system was introduced aimed at improving engine emissions. Gallery References Saturn Corporation engines Straight-four engines Gasoline engines by model