so i have an 84 gsl , it is showing 112k on the clock. when warm my idle oil pressure drops to nil on the gauge. i haven't hooked up a gauge to verify if it is a sender or actual pressure is low. at 3-4 k rpm it is just a bit under 60 psi on the guage. is there a common cause of low pressure like on the 13bs with the pellet? or is the thing just worn out? do the senders **** out?
thanks~

 

first question is have you checked the oil level to ensure its at the proper level? next, what weight of oil are you using?

 

yes oil level is full. and just put fresh 10-40 in it yesterday which is what i run in my 82 as well.

 

anyone ???

 

i would start by testing the gauge and the oil pressure sender per the FSM. in the mean time you can install a temporary aftermarket oil pressure gauge. you don't even need to mount it. just run it out of the engine bay and set it on the strut tower and run the engine. or you can mount it and drive the car and watch for spikes or abnormal fluctuation.

 

confirm with an independent gauge,, mazda oil senders are notoriously vague

with fresh oil and a good level,, if oil pressure is lower than 15 psi ( 1 kg/cm2 ) at 1000 rpm
then you may need to check the system over
-- primary culprit in pre 1988 engines is the oil passage to front cover O ring failing

PS
stock oil system non FD engines should all make 70 psi by 3000 rpms,, if not then issue may be excessive bearing clearances,, or worn pump,, or leaking or blocked pickup

 

thread back from the dead!!
oil pressure is good when cold disapears when warm.
on a aftermarket guage i am showing
cold: 15/65
warm 0/ 35
so ideas???

 

It's hot oil pressure that matters. 0 at idle and 35 at 3000rpms + ? If so there is a failure in your oiling system somewheres. Could be horribly work bearings, oil pump, plugged oil pickup tube, oil pickup tube coming loose, etcccccccc.........

 

well i do know it could be almost anything related to the system, however since the history of the engine is unknown i hoped someone had a more definite route. it simply is the difference between trying to fix the car and letting it go for cheaper as i am moving.

 

its really hard to say without looking at it. since it has pressure cold, i'd think that eliminates the front cover o ring?

 

Did you cut open an oil filter lately?