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.

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 ?

You need a 150 psi gauge.

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.

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.

..A copy a paste from the my350z forums when I had the issue


If the sensor doesn't solve your problem (usually a bad sensor just hits the rail)... then plug in a gauge and check the pressure. The gallery gaskets underneath the timing covers could be toast.

I have an HR motor and I had a similar issue. The factory gallery gaskets on the 350zHR and 370z were paper. They eventually just separate. Luckily, there is an infinity part number (now available as a nissan part number) for metal ones. In the past, you had to replace the entire timing cover. Even though the stand alone gasket is cheap, The labor is expensive.

check my posts:

https://my350z.com/forum/maintenance...st-151k-3.html



https://my350z.com/forum/vq35hr/6102...-look-for.html


pics of my bad gaskets


https://my350z.com/forum/attachments...psumb0lbkl.jpg

https://my350z.com/forum/attachments...ps9sxiyjxc.jpg

I picked everything up at Concept Z

Here is gasket parts list:

Timing Chain Cover Seal O-Ring
Part #: 15066-JA10A $8.36 Qty: 2

Nissan OEM Rear Timing Cover Oil Gallery Gasket, Upper Large
Part #: 13533-JK21A $30.10 Qty: 1

Nissan OEM Rear Timing Cover Oil Gallery Gasket, Lower Small - VQ35HR VQ37VHR - Nissan 350Z 370Z
Part #: 13533-JK21B $4.70 Qty: 1

Nissan OEM 13042-3HD0A Intake Camshaft VTC Seal
Part #: 13042-3HD0A $34.92 Qty: 6

Nissan OEM 13510-31U10 Front Crankshaft Oil Seal
Part #: 13510-31U10 $10.74 Qty: 1

Nissan OEM VTC Variable Timing Control Solenoid Gasket RH
Part #: 23797-EY01A $4.20 Qty: 1

Nissan OEM VTC Solenoid Cover Gasket
Part #: 23797-JA10B $3.30 Qty: 1


Subtotal: $96.32
Shipping (Ground): $14.64
Total: $110.96


Extras:
Replaced all tensioners and chain guides (less than $200.00)

Labor was for 8 hours @83.00 an hour

I went a tad above 1,000 with cleanup/dispose fees, new oil + filter. 1/3rd the price from Satin (Nissan).

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)

IMHO,

I believe they purposely removed the oil gauge to mask the gallery gasket problem. It happened to my buddies 370z right after mine. I went to check for the gauge to see what the start up pressure was... nothing! I just chuckled. "If you don't see a problem, there is none".

I believe a lot of people mistook this as "oil consumption". Those gallery areas hold the pressure for the oil passages in the head. The oil pressure allows the components to essentially "float" while they are moving.

I started noticing it when pressure was at 15psi when warmed up and idling.... then it went to 10. Nissan still called this "OK". The problem gets worse when your in mid->high range RPM's and your not seeing more than 40psi. The components that are supposed to be "floating" by high pressure oil barriers are now going to start touching. On a couple of occasions, I would hold the rpms at 3K and I could hear an ugly tick... was losing oil pressure and something was rubbing.

Your really on the line when the VTC sensors start tripping Cels. Unfortunately, many that ran into this didn't catch it and had to replace the engine.

It makes you wonder what mileage those gaskets go out and when did they use the updated metal ones.

It depends on how you drive the car.... how often, etc... The gasket slowly starts absorbing oil and after so many pressure cycles... it's just a matter of time. The weak points seem to be where the gasket surrounds the bolts.

on my 07 Nismo, I only noticed it after someone pointed it out. I was at 40K miles. It could have started much sooner. This was 2 years ago. DE's have the same issue as well but at later miles(80k+). I believe the HR motors see it sooner... due to the high rev variant... which equates to higher oil pressure.

I was about to replace the entire timing chain cover, which was about 1,800ish alone. It was not until an Infiniti service person on my350z posted the G37 infiniti part number. CZP started carrying them and I am sure they were the "Go To" for them as well.

Anywho... i'm only giving my experience and the OP might not be experiencing this, just i know there was a lot of talk with the VQ35HR's when i was going through it.

My .02 would be get a 1/8NPT T from Homechepo, tie in an oil pressure gauge with a long line where the OE oil sending unit is and see what the actual idle pressure it. If it is low...

If I remember correctly, just pulling the small covers is enough to check. In my picture above, the full timing cover was pulled off. The gallery plate is torqued down from OEM. That gasket blew apart at that left most bolt. When the tech opened that plate up... it was in pieces, separated at each bolt.

I'm sure the pro's can also shine in

update:

i replaced the sensor today, unfortunately i was unable to drive it for a proper warmup due to a snow storm. On cold startup I'm getting 85psi< 1350rpm. i let it idle for a good 15mins in the garage, oil temps wouldn't go over 160f (prolly due to oil cooler) and my idle pressure was bouncing at 15-18psi. when i rev it to 4.5-5k its at 65psi at 160f.

do you think a mechanical gauge from auto zone would show something different, I'm taking the reading from stock sending unit location btw.

otherwise i might just take the timing cover off and see if there is any visual damage/ oil leakage from the gaskets.

If it was me. Think I would be changing galley gaskets.

@OP. And if your already in there... refer to the list I posted and replaced the guides, tensioners, etc.. I didn't replace my chain. I was told it's not necessary, but maybe someone can shine in?

Be a good time to replace the stock oil pump with a better one. :tup:

i will definitely change out the old guides/tensioners since everything will be apart anyway. I guess it would be a good idea to do an in depth DIY too. :tup:

Quick update:

Finally ripped the car apart today, oil galley gaskets were all intact, looks like this motor got the updated versions because they were some composite metal material instead of the old paper style. Anyway i didn't take it apart for no reason even though the gaskets didnt fail, the shitty fasteners did. On the upper galley two fastener were less than hand tight. So this is why i was getting low oil pressure drops, but no ecm codes (p0011,p0021)

Very lucky that they didn't back all the way out and land in the timing chain. :eek:

Due to this reason right here I am going to have mine done when I get my TT install done. Might as well do exhaust cams and an oil pump upgrade too. The motor will be out, why not.

This is on my to do list.

Looks like it was replaced and the mechanic didn't torque them down correctly?

Noop, common issue.

Nope, this was the first time the motor has been apart since i bought it. the two of the fasteners circled in red backed out on upper galley.

Added DIY thread

http://www.the370z.com/engine-drivet...ml#post3735570

I've read too many horror stories about the oil galley gaskets going out. I ordered EPS's kit:

https://www.facebook.com/epstuningtx/

Oil pressure
 

Thanks for the DIY, I am glad you got it resolved. Based on the profile, I am assuming you are SC?
I am looking into a Z, and previously had a BRZ but the oil pressure light/ oil level never came on then boom the motor spun a bearing. When the motor was removed to assess the damage, there was no oil in the oil pan...
I wonder if any of these manufacture sensors are truly functional...