On start-up, I have a very loud tapping/clunking for the first 2 seconds which then goes away. I believe the tensioner is not holding oil pressure between starts and has to build pressure each start to reapply tension to the chain. My question is what seal do I need to look at/replace to correct the problem?

 

There are some that get that noise. There are three tensioners, one for the main chain and 2 more, one for each camshaft chain.

Oil pressure is only present when the engine is running, it is a function of rpms, but if the noise is so bad that a chain may seem lose, I would remove the left black cover on the front timing chain cover and check the tensioner there, maybe it is not out enough, the tensioner doesn't get fully lose as it has stops that keep it from going back in the oil just pushes it slightly back out to tighten the chain again.

 

Yes but it's my understanding that the tensioner should hold pressure between starts. This is a VERY noticeable noise.

 

Spring inside tensioner?
You might try BG Quick Clean for engines, this varnish remover can penterate the tiny oil holes and remove obstructions usually reserved for high mileage units when oil change habits may be lacking.

Sometimes takes 2-3 treatments and back to back oil changes to resolve.

How many miles and have you maintained 90 day change intervals?

 

So that stuff really works? I've always been skeptical about oil/fuel additives.

 

ok sorry i have the same prob.... so take the top left cover from the timing chain and pull it out a bit? Pls correct me if am wrong..pls. so no need to take out the holl front of the car to get in there?

 

There is a TSB to address a momentary noise after a cold start from the timing cover area,it get mistaken for a timing chain tensioner or guide ,there is a spring that keep tension on the VVT sprocket ,the spring brakes or get weekend witch will cause the noise ,these sprockets are not cheep there are about $500 give or take each. we have seen this problem mainly on the early 03-04 models .

Here is the TSB information from Nissan this was originally discovered on the maxmia/altima VQ35 engines but is also a known cause on the 350Z/G35.







Hope this helps

Sam
GT Motorsports

 

very thorough sam... very nice explanation with diagrams!

 

Fuc*. That may be it. Symptoms are the same. It only happens on cold start or after it's been sitting for at least 45 minutes. I'm still conflicted between the tensioner leaking pressure and this spring. Where is the spring in the diagram and is there any way to troubleshoot between the tensioner and this spring? Can the spring be replaced instead of replacing the whole sprocket? Thanks Sam.

 

Somewhat Common to frequently replace tensioners [every 100-150k] to replace self expansion internal spring in older high mileage Nissan V8.

The cost [labor] and lack of technical knowledge among techs makes this a rarity except for a few shops in US.

VVT/VTC sprocket noise common on 300z and J30 v6 going back to 1990.

All it took was one prolonged oil change cycle or running low of oil!

 

The tensioner has teeth that it catches on which prevent it from getting slack - it is not a matter of holding/leaking pressure when the car is off.

 

is the only issue the sound? any other symptoms associated? the spring cannot be replaced individually,,,it is only sold as a complete unit if you opt to replace

 

Pretty much just the sound. It sounds horrible though on start for the first second or two. New built motor in the car with 1000 miles on it and the oil has been changed 3 times already and hasn't been low.

 

Bumping this relic back from the dead... wondering if anyone has had any experience with this issue? How did it sound? Did the noise become constant?

My newly built motor was making noise for 1-2 seconds during startup, then quieting down. Its showing ~90psi oil pressure on cold start and ~28-30psi at warm idle, no smoke out the pipes, changed the oil from Motul 10w30 used for break in and put on a new filter and the noise is now constant and rises and falls with revs.

The noise seems to be coming from the passenger side and the engine builder thinks it is coming from behind the timing chain tensioner cover. My donor core was an oil burner, but I think the tensioner came off the last engine the spun a main.

I found a pic that Gord posted that shows the tensioner on the left side where the allen wrench is:



Again, any info or input on this is appreciated.

I also found a thread referencing the cam gears making similar noise, possible it could be this as well?

 

Chris that is the tentioner I had the loose bolts on when mine made the same noise!! Pull the cover and try to tighten it up, it is worth a try.

And on a side note the picture you posted of my engine is actually the OP of this threads engine as well I bought it from him

 

Gord - did yours only make noise on startup? Mine started like that, but the noise is now constant. Did yours do the same thing?

 

Ok, I can't stand the waiting and today was 70*+F outside so I got out a few tools and did some discovery.

Here is a pic of the tensioner as it is sitting in the car now:



Notice how it appears completely depressed. Also, I believe it is resting at the point where lock to install it is lined up. I was able to slide an allen wrench right in it. Is this how it is supposed to look at rest?

Here is a pic of the tensioner off of the oil burner used as a core:



It seems that the resting position is not fully depressed, but it also has no resistance on it. When I depress it fully, it does not appear to give as much as the tensioner that is in the car.

Can anyone help me out on this Oh, the tensioner in the car appears to have resistence on it, meaning I couldn't push it in any further and there wasn't slack in the chain to move it to the right easily.

 

It seemed to make noise all of the time but it was the worst at start up.