Hi all.
I'm a owner of a r33 gtr. the car is in good condition. stock as a rock. only mods are defi gauges and hks bov.
There seems to be a strange grinding noise coming from below the car. only happens when the car is warm. never cold. roughly around 2.5 kpa on my defi's when i depress the clutch near the friction point. sometimes also happens on idle. when on idle i've noticed it usually happens when the oil pressure on my Defi's drops down a tad. in other words, when grinding noise starts, the oil pressure will drop down a tad. when the noise stops. the pressure will rise up again.
here is an audio clip
now on another issue which may be related. when i turn on the air con on hot days. the oil pressure sometimes drops a few kpa which results in a warning light on my Defi's
my mate's have suggested it may be a cracked or bad oil pump. i thought i'd get your opinion. cheers