Slight rattle at startup

[CMF_sva86]

Just after starting the ignition on my 1l 1996 K11 (usually when cold), it sometimes rattles for a second or two, then the noise goes away.When i have the rattle for 2-3sec on startup my oil light stays on two!Because the reason the of the rattle is the oil system is empty and it take`s time for the oil pump to fill it!But i think this is NOT normal,and there is a reason for the system to drain totally when staying for more time!I know that there is pressure bypass valve in the filter console it self!When you take off the filter it is under it!Have some one changed this valve to see if this is not the problem?Because i have not seen it but this is a simple valve with a spring and a steel ball that open`s at constant amount of pressure but if it is stuck open a little the oil can go back to the sump.That is why i want to see how this valve look`s like,and if some one have more information about it?
This is the valve that i`m talking about:

 

[CMF_sva86]

And another schematic:

 

[CMF_frank2]

the oil pressure relief valve is integral with the oil pump tho eh (on the end of the crank)

frank

 

[CMF_sva86]

There are two valves one on the oil pump(integrated)and the other one is that on the pic!

In the pic under is the integrated:

 

[CMF_sva86]

And this is the valve i was talking about!

 

[CMF_Micra_King]

You sure its not just a timing chain rattle? Thats not uncommon.