dubbingt

The problem is the valve shims/lifters/whatever they are called on this engine. Mine is coming from cylinder 1 on the passenger side. It sucks and I hate it. It just sounds broken. Nothing you can do about it aside from getting it fixed...... and this is an expensive fix.

I barely even drive the car now because its annoying.

Markhimself876

So is it possible that this very annoying sound we are all experiencing is nothing much to worry about? I have the same EXACT symptoms as most of the other guys that posted in here. (rhythmic ticking after warming up, sometimes more noticeable than other days, up to 1500- 2000 rpms) Im almost at 200k miles and she still feels fine besides that ticking.

I was worried that my engine was on it's way out before seeing all of these threads with the same issue. So what is the final verdict on this seemingly everlasting thread?

myfirstzcar

The verdict is these engines have what are known as cam followers, bucket tappets, solid lifters, whatever you want to call them.
Either way, they look like a little cup, and go in between the cam and valve to eliminate side pressure on the valves and obviously transfer the cam's motion to the valve. They have a little kind of 'tit' inside them that contacts the valve, and they are slightly softer than the valve itself to avoid ruining it. The top side is flat.
I don't know exactly why, but sometimes the tit wears down or something else causes the tolerances to open up, creating a noise. This knocking can come and go, or get louder or quieter with temperature and oil viscosity. It can also do it's thing completely at random. The follower can have a tendency to stick in it's bore against the valve stem, which would quiet the knocking sound for one or more revolutions.
The worst thing that can happen in the short term is you'll lose some lift on that valve and be annoyed by a knocking sound.

myfirstzcar

As an educated guess, I'd say replacing them involves removing the timing cover, all 3 chains, and the cams. Checking the lash is relatively easy and a sure fire way to identify the culprit.

5150_91

iTrader: (2)

I have a 2003 with around 135k now on it. Same issue as everyone else here it seems. Knocking after warm up and speeds up with RPM's. Sometimes it can get fairly loud. Everyone that I have had take a look at it just mentions that it is something in the bottom end and then they proceed to quote me on a new engine.. Thing is, it has been doing this for over 6 months so if it was a serious issue I would think by now I would have been experiencing more trouble.

What would be the best way to diagnose this issue?

myfirstzcar

Hold a long screwdriver from the valve covers to your ear, or use a proper listening device.

Lower end knock can also sometimes come go depending on whether the engine is spinning freely or under load, but it will be rhythmic, as in every single rotation, cold or warmed up. If one rod bearing is bad, you can try to count the knocks at a low idle and figure out how many knocks you heard in a 10 second period. If it's idling at 700 rpm and you figure about 700 knocks per minute, you probably have a rod knock.

One lifter will knock half as many times as one rod would knock.

If you have multiple lifter or rod/main issues you need to consult a mechanic that's honest.

A bad lower end will typically cause lower oil pressure.

5150_91

iTrader: (2)

Thank you for the response. And I can proceed to private message you if that makes it easier for you to be notified when I respond.

Upon start-up, like always. No knocking whatsoever. So when I went to listen with the screwdriver, nothing unnatural. Just odd how once it warms up, the knocking can get decently loud especially with the hood open.

myfirstzcar

I don't know much about this fuel damper issue, but you may want to look at that.
Also, It would be nice to hear this knock, since these engines all have valve train noise anyway. What you're hearing may be somewhat normal, and will get louder as your oil warms up.

5150_91

iTrader: (2)

Would any of these mentioned possibilities appear to be coming from the "bottom end" like all these auto shops have been mentioning? Nobody has really taken a full look at it so I guess that's something I can have done. And I can try to snag a video of it soon.

myfirstzcar

It's always a possibility, but lower end issues aren't very common, especially if it's been knocking for 6 months.

Isaacz33

Hi everyone im new to the site this is my first post
2006 350z 94K daily driver mainly highway

im having the same problem, i was also told it was the dampers but after reading a few post on here it seems that it dosent help the problem so i would rather save my money.

I was also told that it could be the fuel injectors i wanted to know if any body has tried that option?

also is it safe for me to continue driving like this?

Thanks

bk88

Oops! I started a thread today on this topic and then saw this one, sorry.
I also have the same knock you guys are talking about and will be taking the car in this week. I hope it's nothing serious, just bought the car! I didn't notice the knock with the fan on and all the outside noises at the time.

myfirstzcar

Video or sound bite?

ClevelandG37

Hey guys, I am new to this forum, and this thread is exactly my problem....2010 G37S. Any updates or solutions?

justinamenta

I just bought a 2004 350z with 69,950 miles on it. By 70,000 miles I started getting the "knock" after the car warms up, at idle. While driving, the engine sounds fine.

turbotoast

You may be dealing with a fuel damper issue and not a valvetrain issue. There was a TSB released by Nissan about the symptoms you are describing.

NOLAGG

iTrader: (1)

So if it is a fuel damper problem how do you go about fixing this?

dubbingt

This is the noise that everyone is having problems with. Not my video but I found it on youtube. Ticking at idle and increases with RPM....

myfirstzcar

That clearly sounds like a cam follower to me.

Musclesmau5

Bump..
03 auto 95k... Same symptoms.