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: