Low oil pressure!
 

Hello All,

I've noticed my oil pressure is reading lower than normal at idle. i would normally see anything from 25-20psi at idle on my defi gauge. Now it reads 15psi and even dips down to 10psi. the Oem oil pressure light hasn't came on yet, and ive parked it till i can find the problem cause this isnt normal. Oil analysis came back perfectly fine, so im thinking oil galley gaskets. Has anyone seen oil galley gasket issues on later models? (post 2012) I'm open to suggestions before i decide to rip the the rear timing cover off.

Sounds like I need to add an oil pressure gauge. Hey Nissan - that would have been better than a volt meter or clock that doesn't keep good time.

Whats more funny is the older 350z with the hr motors came with oil pressure gauges :rofl2:

I think it's one of those things where we all know its a good idea..but if you put it in you are going to get droves of ignorant customers coming in for warranty service thinking something is wrong when the reality is that Jiffy Lube just put in a different oil weight.

It could be the sending unit for your oil pressure gauge. If the idiot light hasn't come on but the pressure is reading that low that could be the problem. The light has it's own sending unit.

I have an AEM oil pressure gauge and it reads about 30-35psi at idle with the oil around 180°F.

Keep in mind that the Z runs very high oil pressure. The bypass valve kicks it at about 105 psi so if you got a oil pressure sending unit that can't go above 100psi it could have been damaged. When picking out the oil gauge I almost made the mistake of getting a 0-100psi gauge. I did a little research and found that a 0-150 is better suited for the Z.

My oil pressure at 220 degrees was 24psi at idle. I emailed Seb about this because I was getting a low oil pressure light on my gauge. He said at that temp, anything above 15psi is good. I need to adjust the low pressure set point on my gauge.

I agree. The problem may be with your oil pressure sensor. Another member (Spearfish) reported similar symptoms using an AEM pressure gauge. After some investigation, he traced the problem to the transducer in the sensor crapping out. You can order a replacement Defi sensor, albeit they are pricey.

Even the 350z with the DE motors came with it...So all of them did. It is my least favorite part of the 370z.

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?

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...

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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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

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.

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.

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.