E36 Cooling System Flush and Refill Part II

Once you have ran the car enough to get your BMW up to operating speed, and have it on jackstands, shut off the car and pop the hood. Look under the car, at the radiator bottom on the driver's side. There is a blue plastic plug. Get a bucket. Use a 10mm socket or flathead screwdriver to remove the plug. DO NOT do this without letting the car sit and cool for awhile first, or risk getting burned by hot coolant!!! You don't even need to remove the plug fully for the coolant to drain. Open the radiator refill tank. A couple of inches to the right of the radiator fill cap is an air trap valve that looks like a large plastic screw. Open the screw with a flathead screwdriver. Now the fun part of changing radiator fluid/coolant on any six cylinder E36 BMW...draining the engine block. The 19mm (or was it 17mm...can't remember off the top of my head) drain plug is located on the side of the engine block. Get under the car headfirst from the front passenger side. Look up - the engine block drain plug is located amidst the headers/collector pipes of the exhaust manifold. Towards the back, near the firewall. There is not enough room for a socket to fit, but a box or open end wrench will fit. Again - DO NOT loosen this plug when the coolant is hot or risk serious burns. Also, this part of the job makes a big mess. I used a cat litter box to collect most of the coolant, but be warned that it's going to get everywhere. Make sure you hose down the driveway good afterwards and keep pets away from the area until dry. Once empty, reinstall the drain plug and tighten. Optional: flush the cooling system with a hose. I prefer to refill the system entirely with distilled water, run til up to operating speed, and drain the distilled water in the same manner. This way you can be sure you've truly flushed the system. . Now, tighten the blue plastic plug under your E36 BMW's radiator, and with the air trap valve open, slowly refill the radiator, block, and coolant expansion tank. I run a 50/50 mix of G12 and dstilled water. Remember glycol-free coolant is a must as E36 BMWs have aluminum alloy engines. As you pour the coolant and water in, squeeze the two upper coolant hoses to help bleed the system of air. Air bubbles and fluid will exit via the air trap valve. Once full, run the car with the heater on full blast, and continue to work the coolant hoses. One article refers to this as 'massaging' the hoses to get the air out. Tighten the trap valve only when coolant that is free of bubbles comes out. This article pertains to all E36 six cylinder BMW cars, including the 1991 325i (Europe), 1991 325is (Europe), 1992 325i, 1992 325is, 1993 325i, 1993 325is, 1994 325i, 1994 325is, 1994 M3 (Canada and Europe) 1995 325i, 1995 325is, 1995 M3, 1996 328i, 1996 328is, 1996 M3, 1997 328i, 1997 328is, 1997 M3, 1998 323i, 1998 328i, 1998 328is, 1998 M3, 1999 M3, 1999 323i, 1999 323is, and all 325ic, M3 Convertible, and 328ic models. Four cylinder 318i, 318ti, and 318ic models powered by the M42 and M44 engines should expect a VERY similar procedure, but check your owners manual for cooling system capacty differences.