I have an 04 automatic 350z and this morning when I started up, my car almost sputtered to start and then it had a pretty loud knocking coming from the engine. It scared the hell outta me. I let it warm up and it seems to have calmed down, but there still is a faint knocking coming from the engine block. I can't be sure if the slight knock wasn't there before b/c you can't really hear it unless you get your head up close and listen.

A friend of mine said he knew someone who had issues with Nissans and their timing chains and tensioners. My first thought was low oil, but I just changed it 1500 miles ago and my oil pressures all look normal.

Any ideas on what to check or what this could be?

I tried recording it with my phone and it's too loud and you can't really hear it, so that won't help.

 

I had a knock or a click apear in my engine one day turned ou tto be an a/c belt it was weird.

 

There is a known issue with vq35de's and timing chain noise but it will usually be a whine as a result of worn/broken tensioners. The clicking you are hearing may be a valvetrain noise.

 

If it only did it once, i got no idea. If it taps hard every time on a cold start and remains very faint on through idle. its the camshaft sprocket. Right now I am having my work tear mine down cause of the same problem. It taps on cold starts, all the guides and tensioners are fine. If you pay to have someone do this (HIGHLY RECOMMENDED) do not try it your self, but it is EXPENSIVE. lots of labor, and if your going through the trouble to have it replaced you need to have everything with the timing replaced. cause if you replace one piece. its gonna suck *** when a month later the other one starts doing this. I work at the place thats fixing mine so my labor cost is 15% of normal labor cost. So my fix is remain under $2000 but if i didnt not work there it would've been a $3500 fix. its around 20hrs of labor. $1200 for parts replacing everything including all new gaskets at my cost. I posted some pictures below of my block torn apart. If you do not have this fixed sooner or later its not gonna do anything but start throwing codes.



^^ If your not to familiar with what your looking at. the valve covers and whole intake is removed from the top and the timing chain cover and all belts, radiator, fans are out the way. The sprockets are the large round gear boxes on the right and left. this car is built with three timing chains. 1 small chain around bank 1 cams and another around bank 2 cams. then theres a large chain going from the crank up to each camshaft sprocket to help keep the chains on the same time.