Summary of work, requiring advice from here...

have you actually had your head near the sump when diagnosing where the sound is coming from?

we determined my brothers sr20 had done its cam bearings until we pulled the motor down and found a spun rod bearing

 

The mod bug is starving to death at the moment

 

came in late on this, and apologies if I've missed some posts in the middle, but a couple of general comments.

Dunno how hard it is to find a new stock harmonic balancer, but for the effort of pulling one off, if there's ANY doubt, I wouldn't be putting it back on again. As for the Woodruffe key, it's small but significant. See if you can buy a new one from Nissan, and install it carefully! The damage to the woodruffe key I can just about guarantee is because it wasn't placed correctly in the crank when the harmonic balancer was reinstalled. It dropped down so it was out of alignment, and someone has bashed the harmonic balancer on which has caused damage to the woodruffe key as well as the harmonic balancer. The woodruffe key is designed to sit flat in a groove on the crank, and sit proud of the crank in a corresponding groove in the harmonic balancer, and be a snug - almost interference - fit. Look closely at the pic of the harmonic balancer (and the fingernail model's hands ) and you'll see that the harmonic balancer has bits of metal broken off around the woodruffe key slot. If there's similar damage on the snout of the crank, get some advice from a Loctite expert about what you can use to make sure the new woodruffe key is held tightly in place.

As for the horrible noise, I reckon it might be the VTC springs being broken or weak, which I think allows the cams to bounce around at idle. Find someone with a ConZult, hook it up and activate the VTC solenoids at idle (they normally only activate at revs, never at idle), and see if the noise goes away. If it does, start suspecting the VTC springs.

Twin Terror is right about harmonic balancers in the V6 Holdens, but they are a different case. They are a 90 degree V6 which needs to be heavily dampened, which gives the harmonic balaner a hard time. The Zed motor is a 60 degree V6, which is inherently a lot smoother, and gives the harmonic balancer a much easier time. Having said that, looking at the pics of yours with the cracked bits on the woodruffe key slot, dent and cracked rubber, I'd use it as a doorstop, not a Zed harmonic balancer anymore.

Hope this helps.

 

Thanks for the input. I replaced the harmonic balancer and the woodruff key, as well as the cam gears and springs (the ones on the front of the gears). Unfortunately when I put it all back together the noise was still there..... So when I have time I'll pull the plenum and have a look under the rocker covers as I believe that's where the noise is coming from.

 

Ow! Bad noise! Go to your room!!!

Sonnds bad, but hard to pick what it is. The only clue I picked up is that it was on increasing revs, and not on over-run when the revs were dropping back down.

Lack of oil pressure, or lifters or VTC not picking up oil pressure when revs are increased?

Is it evident on both banks? If it's only on one, then buggered rocker/cam follower/lifter? It doesn't quite sound fast enough to be a crank rotation noise. Others have mentioned trying the ConZult cylinder balance test. If you try that in manual mode, you might be able to pick up a difference when you try dropping out one cylinder at a time while manually increasing the engine revs.

Another thing to try - some people have mentioned a length of hose to pinpoint the noise. A length of steel, like an extension bar or a long screwdriver is much better to isolate higher frequency noises like the one on your car.

Fingers crossed for you!

 

Trash it...

and get a new one. The key doesn't hold the balancer in place per-SE, it just insures that it stays aligned. But that key is shot, and so is the balancer. Those sharp edges might eat into your alternator belt. A good used one should be easy to come by, and relatively inexpensive.

The cam gears will show no external sign of wear. Depending on the style (early or late) often times the early ones would leak oil when they started clacking.

 

Even if it's not the VTC springs, before you start pulling things to bits, at least try a ConZult and activate the VTC solenoids at idle to see if the noise goes away, or at least changes. It just sounds too much like a top end noise to be considering pulling the engine at this stage.

At the very least, it may help point the finger more closely at the area that's causing the noise.

 

Sorry man...

I replied without reading through most of the thread.

The gears you put on for replacement, were they new? If not, how many miles did they have on them. I have read of several instances of the gears being so worn out that they would make noise regardless of whether or not the VTC solenoids were engaged or not.

Pull the timing cover off that side, and CAREFULLY, with the motor running, place your finger lightly in the middle of the gear and rev the engine. If it is a worn out gear, you will be able to feel it very prominently through the cover of the gear.

My cam gears rattled like mad with the JWT 500 cams I had in the car before, and I could feel it clacking when I would place my finger in the center of the gear cover.

Other options to consider, broken valve spring, or a lifter that is not quite up to snuff. Were the heads redone on the car? Were the lifters kept upright when they were removed?

 

Thanks I'll try the finger on the gear when I get back on the job. The heads were done as part of the rebuild but that's all I know about it. The replacement gears came from a reliable member. Apparently they were good when removed.

 

I was gonna also say dry VTC gear. Im thinking being rebuilt and it ran fine for 2000kms it wouldn't be valve related unless something has snapped. Old reused parts like a dry intake gear could be, lifters are also unpredictable but it would have to be totally seized in closed position to have such a rattle. Blocked oil gallery could also be if it wasn't put together clean or engine and heads weren't properly cleaned.

ALso some noises appear to be up top but can transmit noise from bottom. Really need to use something like a screwdriver and listen top and bottom of engine.

 

Just back to the gears Marcus - the ones you removed from your car, could you turn the inside of the gear with your hand whilst holding the outside of the gear????

Matt.

 

I didn't really give a good go Matt, but I don't think so. I'm pretty sure I had a superficial attempt at looking for movement but there was none. I just went out then and had a listen with a long screw driver and as we already thought, the noise seems to be coming from the front passenger side beneath the rocker covers. I had a listen around the bay and on both sides and it's definitely much louder right up top front (screw driver on the rocker covers).

 

Sounds like the gear area there. You talking intake cover Marcus?

 

Yep

 

Finally found time to remove valve covers.

It's taken a while to find some time to get to these valve covers, but with the deck almost built and rain interrupting play, today has been the ideal opportunity to get stuck into it. No real problems getting everything apart, but I'm not sure I'm any the wiser. I was really expecting to see something clearly wrong once I removed the valve cover.....but I cant see anything suspicious?? Just to summarise, the rattle is more significant than a tick, tick, or light tapping sound. It increases in volume and frequency with revs. At idle you cant really hear it. It's made worse with rapid acceleration. When you bring revs up slowly it is still there but not as pronounced as when you hit the throttle hard. I used a screw driver to listen around the engine bay and was convinced it was coming from the front of the engine (passenger side) and was loudest when on top of that valve cover. That's why I expected to see something as soon as I removed that cover. I'm not used to looking at these things an my experience is quite limited so there are some photo's below in case someone else can spot anything I'm not seeing.

Any advice on what I should be looking for next, and how check it?

"Piston slap" has been mentioned, is there a way to check for this?

Of course all advice and ideas are greatly appreciated.

Here's the noise again: http://youtu.be/ojzGbz8oI0E

 

Great....why do you say that Rob?