So, I just recently bought an 03 Daytona Blue with 155k from an insurance auto auction for what I consider a steal($1900)! I purchased the car because it was labeled a Run&Drive and the damage it was slavaged for was to the roof, which in my mind was much safer than a front/rear end collision.. After getting the Z home I quickly replaced the battery and went to fire it up with my heart in my throat I depressed the clutch pedal and turned the key. What I heard was a dreadful engine tick/knock that was increasing intervals with the motors RPM , no CEL/SES lights present.
I have done a fair bit of reading on this forum and few others; some point to the valve's and others say it could be as simple as a fuel damper. The noise is very audible while the hood is up and from what i can tell it sounds as though it is coming from the passenger side of the motor.
This is my second 350Z I purchased from iaai and the first was an 06 rev up that self detonated within 4k miles, needless to say I have a pure love for this automobile and there is nothing I want more than a clean running and driving 350Z. Im sure I will be told "Shoulda bought an HR" but the reality is I am only 20 years old and working for minimum wage an HR is out of my grasp at the time being. If anyone can shed some light on my situation and help me figure this out I would greatly appreciate it, Thanks for reading about my Z and I wish you all better luck than what I have been dealt!

 

If it's not an exhaust leak it's going to require the motor to come out. It doesn't sound like rod knock to me but it doesn't sound like an exhaust leak either.

 

Sounds like it was 155k miles on dino oil...

My revup was knocking like crazy when I first bought it. I really didn't know how poorly made the DE's really were at the time, so I assumed it would run trouble free like my VG30dett to 300k+ miles.

The knocking got worse, so I assumed there was no oil circulation to the heads. Ran 1qt of MMO and 4qts of M1 0w40 for a few lightly driven OCI's. Ensured PCV was flowing and there were no crankcase leaks.

Car stopped knocking eventually--but burns oil. No significant amount of metal shavings on my goldplug. I'm sure the rings are still gummed up from the PO running conventional oil.

For $1900, you can afford to run 1qt of Marvel mystery oil and 4qts M1 0w40. It's a light but effective cleaning for VQs that have been abused by the owners running conventional oil.

 

That's kind of a ridiculous statement to make regarding conventional oil given the literal millions of miles on millions of vehicles with no issues including my own z with 104k miles of conventional. I could believe poor maintenance causing all of that but not just conventional oil.

 

^+1

Did you change the oil or at least check the oil level?

 

Ridiculous? Not even slightly. No issues is relative. You over extend a dino OCI with mild fuel dilution and you're going to have unseen problems. What's to say the OP's engine didn't have a long--short tripped--OCI on dino?

 

So today I pulled a few things out of the motor to do some cleaning, intake and such also did an oil change which went ok the oil wasnt too dark and nothing in it to raise concerns. After removing the intake I noticed a really bad valve cover leak and to my surprise the front corner bolt to the valve cover was half way loose... Obviously this scared this crap out of me and is making me wonder if someone was under it trying to diagnose this sound I have. Furthermore I wonder if this previous owner did it himself couldn't figure it out and to kinda wipe his hands clean he jumped on the roof and called Geico the morning after saying his car was vandalized.. Doesn't seem crazy to me especially in the case this Z came from New York City and I found the previous owners AT&T name tag, too be nice he doesn't look like a very sharp fellow. What do you think I do next?

 

You mean like 99% of vehicles on the road? Last one went 220k on dino oil on 5-6k intervals and never burned a drop of oil and is still running. I could go on with the rest of my family and friends vehicles but the point is it's not damaged by using regular motor oil.

Question, have you ever done an oil analysis on regular motor oil for extended drain intervals? I have. It's why I no longer spend money on synthetic.

 

How much oil did you drain?

I have a friend with a G35 that he didnt take care of, let it run so low on oil the oil light came on and the valvetrain was rapping like crazy just driving. Added 2 qts for him and it went away and told him to change the oil asap.

So, you need to remove the intake and plenum, fix the valve covers with new gaskets, inspect everything with them removed, make sure the valve cover oil drainback and PCV valve arent clogged. Although if low oil was the issue and you changed the oil you could just start it and see if it goes away.