Oil pressure loss!!!

[SR20RX7]

I recently got a built motor if a guy has about 30k on it.. Have a enthalapy tuned ecu... Has Tomei turbo mani an greddy intake Aeromotive FPR. Blew my old motor n picked this one up... Installed and she runs great idles good, good air/fuel ratios and sounds really good.. The issue is oil pressure, cold start she Has bout 75-80 psi then she warms up and idles at about 25... Let her idle for an hour several different times like that before driving... Once I drive the oil pressure is kinda weird.. 3200 Rpms is anywhere from 50-65 psi then at idle she has 11 down to 5psi... Only goes that low once I drive... Any ideas??

[brndck]

5 is way way low. i'd be hesitant to even drive with that low of pressure for fear of scoring a bearing.

first things first, drop your oil pan and make sure the pickup isn't damaged/cracked/tweaked, and that the gasket for the pickup isn't fucked up.

its possible your oil pump spring is weak/failing, but its very very uncommon.

[SR20RX7]

Ya I'm not driving it anymore its gotten progressively worse over the 300 miles since install... It would idle at 22psi then kept dropping... Will do I gotta lift the motor to pull the pan it's a one piece oil pan rear sump it's in my rx7fc... Weird thing is it has oil pressure while driving but not idle... The vehicle I got it from was rolled over twice btw...

[ultimateirving]

Where is the oil pressure sensor connected? if you used any type of thread tape it can cause the sensor to jump around and provide false readings due to it not grounding itself out properly

[SR20RX7]

No it's a mechanical gauge fitted into the factory location... Would air in the line affect it?

[ultimateirving]

No it's a mechanical gauge fitted into the factory location... Would air in the line affect it?

Technically air is compressible and oil is not, so it is theoretically possible that air could be impacting the fluctuating oil pressure change, i havent ever considered that. How would you remedy/bleed the pressure gauge.

My cheap ass sensor is electrical and only has the pressure sending unit right at the factory location and there is a wire running to the gauge. so Minimal chance for air

p.s. what sr do you have? s13 s14 s15?
The s13 oil pickup is the least functional, upgrading to an s14 pickup is pretty common because it has a wider mouth for sucking ;)

[fliprayzin240sx]

Another question is what weight oil are you running? If its too thin, that could contributing into your low oil pressure at operating temp.

[SR20RX7]

I've searched on here and found no similar issues.... I'm running 15-40 tried stabilizer to...did oil change running rotella t5.. I'm thinkin pump is going but idk...

[hobbs]

What temperatures are you seeing the low oil pressure at? Oil will thin when it gets really hot, keep an eye on your water temp gauge. Also I would take a look at the oil pressure sender, vibration is known to kill sensors pretty fast. Also what is your idle set at? I've seen that low of oil pressure when trying to find a very low idle issue on a friends car, hovering around 7 psi at 500 rpm or so.

Also one thing a lot of engine builders miss is the chain oiler, if it's not locktite'd in over time it will fall out causing low oil pressure at idle.

[fliprayzin240sx]

If you're using that thick of an oil and its still dipping to less than 10 psi at idle, I'd be leaning more on a bad pump. You can check the pick up like said before but that doesnt explain why it would be low when the engine is up to temp. If the sump is clogged, then it would be low right at the bat.

[SR20RX7]

I've got a mechanical gauge so I dnt see any effect ith vibration... Running a stock gauge for temp and its right in the middle... I ordered a new pump an will be doing it soon just waiting on more parts. Just sucks 3rd time pulling the motor... I want a s14 pickup but I have a custom pickup since its a rear sump conversion since its in my RX7...