Oil Pressure delay 500SEC
 

Just in the last couple of weeks I have noticed that upon a cold startup it takes several seconds for ANY oil pressure to registar on the gage. As soon as it does, it always remains above 2 bar and 3 at anything above idle. This is on my 1985 500SEC with 115k miles. I know it is not a gage problem sice I had my wife start the car while I watched the camshaft oiler tube through the removed filler cap. Sure enough it took about 6 seconds to see oil. The car is now in the garage until I find the problem. My research suggests that the oil filter housing is draining empty as the car sits and therefor must be filled up by the oil pump first before I get any oil to the engine. I pulled the oil filter housing assembly off the block and see the little spring loaded check valve in there. Can this little sucker be bad? Can I get new parts for it? Could anything else cause such a prolonged delay in oilpressure buildup?...collapsed lifters? ...bad oil pump? ...Any ideas? Thanks, Brant

These go bad eventually in the M119 engine in the 500E, this could be your problem as well.

http://www.peachparts.com/shopforum/tech-help/20032-500e-still-racka-rackas-cold-start-up.html?highlight=500e+oil+valve+replace