Halcyon Auto Parts - For BMW 750iL Engine Coolant Reservoir Cap-Base 1991. 1991 BMW 750iL Base Sedan 4-Door 5.0L 4988CC V12 GAS SOHC Naturally Aspirated. Type : Engine Coolant Reservoir Cap. 1991 BMW 318i Base Convertible 2-Door 1.8L 1796CC l4 GAS DOHC Naturally Aspirated.