I obtained a 1986.5 Hardbody extcab SE pickupwith the VG30i engine. Its externally a well cared for vehicle,but some potentially serious questions under the hood.

Right now we're looking for the source of a noise andI've received several opinions. It seems to me that a fairly recentvibration dampener change and a just now fan clutch changemight have been done on the basis of misdiagnosing this noise.

The previous owner claims to have changed the timing beltat the required 60k intervals, but there is no documentation for this.So, we're going to have to do that.

The noise may be in there somewhere, but it is a variable noisethat seems odd to me.

So, I thought I'd post a video clip of the noiseand see if anyone has had similar experience and/orcan offer useful suggestions.

If you are inclined, please visit:

http://www.thecriticalcrab.net....html

I'll be interested in any suggestions and all comments.

Here's what you need to do to narrow down the possible culprits.This is something I learned when I had a vibration noise on my Xterra which also fluctuated with RPM. My issue was the alternator but it had a few people scratching their heads because the whole engine would vibrate.

Remove (don't just loosen) the Air Conditioning Belt and run the engine. Listen for the noise. Is the noise gone? It's either a faulty AC pump or the tensioner pulley. (The tensioner pulley has a replaceble bearing, but you will have to deal with a bearing supply store to get it.)PS the pulley assembly runs about $60.00 from Nissan...the bearing is under $10.00.

If the noise did not go away:

Next remove the alternator belt (The battery light will come on but don't worry about that, you won't be running it long enough to kill a battery.) Listen for the noise again. If the noise is gone chances are the alternator bearings are toast and you need an alternator. Go with a rebuilt Bosch from your local aftermarket parts dealer if you can because the warranty is typically better than other units.

If the noise still didn't go away...

Pull the powersteering pump belt and listen again. You pretty much know what to do from here.....

Now you have no belts and the noise is still there. The timing belt could be rubbing on the timing cover or the T-Belt tensioner, located on the right side of the engine, may be the source of the noise.

I have the engine trouble shooting guide for my Xterra 3.3L which is quite similar to the 3.0 engine as your D21. Check your HOTMAIL address for the file!