Need Help Identifying Engine Tick/Knock! VTC? Lifters? Maybe Knock?

[vereshchak]

Hello everyone,

I park my 1990 300zx TT in storage during the winter season and start it up everyone once in a while. Today I went to start it and heard a prominent knocking/ticking noise coming from the engine. I shut off my car and checked the oil levels immediately to discover my dip stick was pretty dry. I topped up some oil I had in my trunk but it wasnt enough to fill the whole crank case. I'm nervous the last times I ran my car over this winter season might have been on low oil. I started the car again and it still had the same sound but altered slightly. I'm very nervous that it may be a rod knock but I'm praying that it isn't. I started doing some research and found that maybe its from a bad timing belt and tensioner or the VTC rattling. Maybe the low oil and the low winter ambient temperature is making my lifter tick significantly worse? Please help me identify what this sound is, I was hoping to take my car out of storage within a week or two!

Here is a video I made of the sound. It is more prominent on the passenger side near the back of the engine bay if I'm not mistaken but I could be wrong.
https://www.youtube.com/watch?v=W81MoKjEGJ4

I plan on giving it a full engine flush and oil change to see if it helps. I can post more videos if needed!

[vereshchak]

More videos of the sound

https://www.youtube.com/watch?v=_zVU51wZO4A

https://www.youtube.com/watch?v=54L3sNlgJrE

[nissanfreak12]

That sounds to be lifter tick, too fast for a crank bearing. Change your oil and let it run for a bit to fill the lifters back up with oil. If it doesn't go away, you may need to flush the engine to get all the gunk out of the lifters.

Z1 has a good flush that has worked for some old friends.
Adding 1 quart of automatic transmission fluid right before an oil change worked well for me.
Marvel Mystery oil is known to do the same thing, but no oil change needed for this.

[vereshchak]

Thank you for the help. The thing is i know I have a lifter tick as well but if you listen to this video especially

https://www.youtube.com/watch?v=_zVU51wZO4A

you can hear the "jack hammering" thats really new

[nissanfreak12]

Lifters that are really collapsed will make that sound, so will an exhaust leak. When you went underneath, it still sounded muffled. Still not slow enough for a bearing or rod knock.

If you are still uncertain, take it to a shop to have them listen or let it run and see if it goes away. It should clear up in a couple of days of running/off cycling.

[vereshchak]

Here is a better video which clearly shows the louder knock/tick over the regular lifter noise. It sounds louder from underneath but I am still not certain

https://www.youtube.com/watch?v=I_ccu1EJzpU

[vereshchak]

update

https://www.youtube.com/watch?v=2JxeMjY3M90