ive searched, and all i can come up with is the senders tend to go bad.
i just swapped a streetported TII motor into my 86 basemodel, and i drove it around the block and i noticed the oil pressure slowly dropping to under 30psi.

someone please explain to me what it could be, and what it could harm. the motor i bought came with the M.O.P. deleted, and i run the 100:1 premix ratio with tcw-3 2 cycle oil.

im being vague because im pressed for time right now. im sorry.

 

it drops to 30lbs when your driving along or at idle?

 

i noticed it while i was driving around the block for the first time. so i shut it off asap.
it was running for around 1 minute sitting, then about 2 mins of driving (very leisurely) not getting past 3k rpms, and not even leaving the vaccuum portion of my autometer boost gauge.

 

my gauge sits below 0 for oil pressure lol.. oil pumps do not fail though

 

at idle mine sits at around 20 or less. i have an auto meter gauge though.

 

well im hoping it is nothing serious because i just worked my *** of swapping this in, and i spent every last dollar buying everything that i needed so i could "get by for now". i know its not the right way, but it happens.

as for the oil pump never failing, does anyone want to back that up? im sure its possible, but i hear it from time to time that the oiling system is very good in s4's (besides the 2cm omp oil injector spread pattern problem).

 

wait i thought u said the OMP was deleted? and u premixed? If so, you have no oil metering pump and lines. and ur premixing so you should be okay. is ur engine leaking anywhere?? maybe the oil cooler lines are leaking, if so replace them with steel braided ones, they last forever. Oil pressure should build up when u rev higher, and drop when u idle...

 

I've also heard it's extremely rare for the oil pump to go bad. The pressure regulator, however, or that little o-ring between the front cover and the block... those can go bad.
Or it could be a simple as you need to add more oil.