So i bought a 91 318i rebuilt the motor this winter and am just getting to run it now. The head and rotating assembly were assembled by the machine shop that did the work. Upon start up i expected a loud motor as per oil having to get around the motor but it didn't quiet down after about 5 mins of run time. I'm nervous about running it any longer then i already have, i pulled the valve cover off and checked everything seems to be lubricating properly and no wearing that i can see. HELP!!!