Alex Tappin

Okay. For about 4 days I have been on every forum and every possible Google search on this.

I have a 2003 350z that is showing signs of low oil pressure! At warm idle, the car will drop to 0 pressure and the light will come on... I just replaced the oil pressure sending uinit (it was pegging my pressure at 120) and now it is showing low pressure at idle... I checked the dip stick, wiped it then put it back (all while the car was running) and upon pullin it out, it was still full of oil up and down the entire stick even tho my car gauge is saying 0 oil pressure and the light is on. I went to autozone and they said no codes were being thrown.... What gives??!

I had thought maybe I had the issue in the timing belt cover galley gasket but it is not throwing codes. I thought maybe the bearings were going out but I cut open my used oil filter (just changed oil) and there was absolutely no metal parts in there at all. I have yet to hook up a mechanical guage and check the pressure that way.... I guess this is my last hope (and hope that there is pressure)..

Any thoughts?

Thanks

Update: I hooked up a mechanical gauge and oil pressure is reading perfectly fine. Could 2 oil pressure sender's be faulty? Could there be some type of short in the wiring?

Solved update: I bought a factory Nissan unit and installed it. Car now reads normal. Beware of eBay and AutoZone sensors as they read lower than the actual pressure.

travlee

iTrader: (8)

http://lmgtfy.com/?q=low+oil+pressur...e%3Amy350z.com

Alex Tappin

If u notice, all the links have been visited already (up to page 7 on google)

zakmartin

Any engine mods we should be aware of? What's the mileage on the engine (this is the most important piece of information you could have shared). Is the engine making any unusual noises?

Since you replaced your sending unit (OEM replacement, I assume) and it's still giving a low reading, check the sending unit with a DMM. If the sending unit's fine, then it could be the gauge. It could also be clogged journals, junk in the oil pump, worn bearings, something clogging the pickup screen, etc. etc.. Looking at fresh oil filter media isn't going to tell you nearly as much as looking at the old oil filter media would have. An engine oil analysis of the oil that came out of the car when the symptoms started could have told you a lot.

Whatever it is, if you're getting low pressure, DON'T drive your car unless you want to take the risk of watching the engine self-destruct. My recommendation is that you tow it to your favorite local garage to have someone qualified look at it. I hate to be the bearer of bad news, but short of a bad gauge, low oil pressure is usually the sign of mechanical failure and that's an expensive (or time-consuming) fix.

Alex Tappin

Thanks for the reply.

Stock everything. Frequent oil changes. And the oil filter I checked thru had about 3k miles on it. 130k miles! No unusual noises (except for a rattle in the exhaust at around 1.2k rpms)

Would this effect only the car at idle? This is only a problem at idle and if I press the gas a little (reving to about 900 or 1k) the oil light goes away and the pressure up.

Thanks again.

rancor

The oil pressure is dependent on engine RPMs as the oil pump is driven by the crank shaft. If your oil light is coming on at idle the engine is probably not getting adequate oil pressure at any rpm so don't drive it.

Also your oil level should be checked when the engine is off and preferably in the morning after it has been sitting for the night.

Alex Tappin

Just checked my oil level this morning and it is a little below the H. I am going to go buy a mechanical gauge today and see what the oil pressure really is.

Alex Tappin

Yes!

I hooked up a mechanical gauge and got it all warmed up. After complete warm up (10 minutes of idle plus some runs to 4k rpms) the lowest the pressure got to was 27 or 26 at idle.

What does this mean then?? Is the electrical connection for the sensor messed up? Did I get a new faulty oil pressure switch?

Alex Tappin

The connector seems to look fine... How do I TEST if it is good?

nizmo_0385

iTrader: (5)

What guage did you get and how do you hook it up? I want to check mine as well because my guage also reads low at idle only

Alex Tappin

Harbor freight<br/>





Rught there

Alex Tappin

What year?

nizmo_0385

iTrader: (5)

Thank you. Whats that its screwed into? Oil pan?
Mines an 07

Alex Tappin

So there is a part right by the oil filter that is called the oil pressure sending unit. Here is a picture of my old one



Take this out and then hook up the mechanical one!

Alex Tappin

With the engine in your car, there have been many problems with the gasket in the rear timing belt cover! They were made out of paper material and break. It is about 20$ in parts but labor will kill you in money! Unless you do it yourself. Take your car to autozone and see if it threw any codes, they will test it for you.

nizmo_0385

iTrader: (5)

I see now. Be careful ive heard horror stories when removing or installing that piece that the area around the threads likes to crack.

Take this out and then hook up the mechanical one![/QUOTE]

Alex Tappin

[/QUOTE]
Yup! I have a torque wrench and make sure to torque it to 12ft/lbs. Not much.

If the mechanical gauge you hook up reads correct, let me know! That means we have the same problem.

nizmo_0385

iTrader: (5)

Yup! I have a torque wrench and make sure to torque it to 12ft/lbs. Not much.

If the mechanical gauge you hook up reads correct, let me know! That means we have the same problem.[/QUOTE]

Well my car is still under warranty and it reads about 12-15 at idle which dealer says is within range so they wont do much and i dont want to risk voiding warranty by messing with something so ill have to let it be

Alex Tappin

Well my car is still under warranty and it reads about 12-15 at idle which dealer says is within range so they wont do much and i dont want to risk voiding warranty by messing with something so ill have to let it be[/QUOTE]
Should never go under 14!... Have em hook up a mechanical gauge to check it out..

zakmartin

On a 2007, oil pressure at idle should read 14 psi. At 2000 RPM, it should read 43 psi.

Here's the FSM link - go to page 7.

It's nice to see someone finally doing some actual diagnostic work for a change around here. I'm getting sick of people swapping parts "just because."