BMW Repair: knocking at engine start up, overhaul time, 535i bmw

Question
There's a knocking in the engine at start up, then a few seconds later it smooth's out.  What could this be, i have a 1985 535i bmw.  Please help

Answer
The first step would be to check and see what the oil pressure is,being that vintage it probably has many miles on it if your not the original owner than you don't know the maintenance that has been done. The lower knocking noise maybe excessive clearance in between the bearings and the crankshaft(engine overhaul time)or have the valves been adjusted? they too make a noise being adjustable and having excessive clearances will cause a noise until oil pressure gets to the rockers.