Low oil pressure!

jmroy6

Just seems weird that it would read low at idle but function fine on cold startups 90+ psi. A replacement sensor is on its way, hopefully it does the trick. The sensor reads 150psi BTW and its tied into the stock sending unit location. Where is your AEM located? Is it manual or electronic?

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2012 370z GTM SC

mults

It makes sense that the pressure is higher at cold startups because the oil is thicker and takes more pressure to move it around the engine. As the oil warms up, the viscosity changes (gets thinner) and the pressure drops accordingly.

I don't see a mention of the oil you are using, nor the viscosity (10W-30) for example. Maybe your oil is old and just needs to be changed?

Keep us posted to see if the new sending unit changes anything...

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jmoneyz34

Just so you know there is no such thing as weight when it comes to oil. The W stands for winter... also the viscosity goes up when the oil gets hotter not down. When the oil sender goes to max usually an indicator the sender is bad.


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jmroy6

i understand a higher pressure on start ups, but if the gauge is "faulty" and causing a lower reading at idle i would assume the gauge would read incorrect all the time not just at idle.

you know what im saying?
always used redline 5w-30

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2012 370z GTM SC

Rusty

OP, you was saying that your normal oil psi is 20 to 25 at an idle. Now it 15 psi. What is your normal operating psi and what it is now? Once you replace the sensor with a new one. If it stays the same. (I believe it will). Your first guess on the valley gaskets, would be my first guess too. Your oil pressure gauge is saving you from a major rebuild.

I have a set gaskets in my toolbox for just in case.

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Jhill

I would try to back up the reading with an actual oil pressure test kit before you jump into any major repair work. Not sure if they've gotten better but in the past I just haven't had good luck with the electrical gauge kits and they seem to fail exactly as your saying (low reading at idle), something about that range in the transducer seems to get wonky. The factory is more than likely just a switch and it seems to be much easier to make a reliable cheap switch than a reliable cheap transducer, probabaly one of the reasons why the snap on transducers cost about 300.00 (that and they say snap on) and most of the electric gauge kits at least in the past use fairly cheap sending units.

Matco makes a pretty damn impressive engine and trans pressure gauge kit with all fitting for fairly cheap (I think I paid about 120.00), don't buy snap ons it's a rip off.

Rusty

I got a Stewart Warner mechanical gauge that I've used in my past years. What I've seen is that the sensor fails completed- reading. Reads low-from a piece of junk stuck in the orifice. Low readings from worn bearings, bad hydraulic lifter, split push rod, oil galley plug backing out. Loose oil pump. Mounting bolts backed out. I've played around with the 4to20ma transducers at work. Some of that works on less then .5 volts.

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jchammond

Rusty,
On an aftermarket engine oil pressure gauge; Is it 100 or 150psi that it needs to be able to read,,,as i know these engines have high op on cold start-up's ?

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jmroy6

My oil pressure gauge read 75psi at 2.5-3k rpm at operating temp (180-200f) and has stayed constant since day one, the only thing that has changed is pressure at idle. The replacement sensor will be here Monday, and ill report back.

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2012 370z GTM SC

TBatt

Electronic.

Your oil can have an affect on idle pressure too. Not to start another oil shootout but I run Mobile 1 0-40.

My 1977 Fiat Spider would have the oil pressure drop to the point that the oil light would flicker at idle. After installing an oil cooler on the car that problem went away.

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NissanTracker

I saw high oil pressure when i was using Mobile 1 0-40. Granted, I also have a 35 row front mount oil cooler(with a thermostat). Took forever to warm up before driving. Great for forced induction (turbos especially)