I bought a 1997 528i with 2.8l six cylinder. i am going to fix it for teenage daughter to drive. It overheats in about 4 miles. The previous owner replaced the water pump six months ago. He also replaced the thermostat,housing, and overflow tank. He did this this past weekend. He got mad because it still overheats. I am not a mechanic but like to tinker. Any ideas what would cause this.Thanks in advance.