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Name that sound!

Imagine if you will, the sound of a sink drain pipe, galvanized steel maybe, about 1.5-2" in diameter. Imagine also a bench-grinder outfitted with a wire wheel. Now take said pipe and apply to said wheel. The imagined sound wound of course sound like the sound of a wire brush against a hollow metalic object.

Now imagine the sound coming out of an engine. Note I say ENGINE, not fan assembly, not brake rotor, not alternator, not belt.

What could it be?

A Peterbuilt! Run!

Seriously, without knowing anything at all about the engine, vehicle, maintenance, mileage, or conditions under which the sound happens and when it began, it’s really impossible to guess.

Is it possible to get any more specific as far as front of the engine, rear, side etc. Any other things going on that might give a clue?

Oh!?? the old “drain pipe against the bench grinder wire wheel rubbing sound?” That’s none other than your Left Bank camshaft (fwd) bearing going out. You have approximinataely 132.4 miles left to drive before it does enough damage to shut down your motor. They’ve came out with an improved camshaft bearing plating material that makes those last over twice as long as your current model. I believe those have a factory recall and if you hurry down to your local dealership, they will replace it free.
Seriously, it is quite hard to perform any type of diagnosis through a forum-post-type website strictly based on analogies using common household items. One idea is to take a short length of garden hose, pvc pipe or other tube material that will transmit sound when one end is placed against your ear and the other end is carefully moved around (avoiding contact with rotating parts). This is quite an effective method, if you’ve never tried it, you might give it a try. I was really impressed the first time I did. You might be able to spot locate the offending item.

What could it be?

It could be time to start combing the salvage yards for a new engine.

serves me right for posting my own pathetic attempt at a puzzler.

So, the deal is, my 96 Nissan Sentra just started making this sound about two weeks ago. I can’t pinpoint exactly where it’s coming from in the engine compartment. I want to say it’s close to the front of the block near the exhaust manifold, but I can’t really be sure.

The sound is there at idle, but of course as the engine revs it drowns out the sound. Engine has aprox 148k, oil changed every 3k when I bought it at 100k. New Alternator, Nearly new starter, 1 yr old water pump. Plugs are new, I did notice the plug from Cyl 1 had a bit more carbon build up than the other 3.

I do have an electrical issue I’m trying to diagnose but I don’t think that’s related (See thread about headlights diming)

Get hold of a mechanics stethoscope, avoid letting loose clothing, long hair, etc from becoming involved with moving parts, start the engine, let it idle and start listening.

Don’t forget to listen for worn bearings in all components plus the engine block. You may get lucky enough to find the problem.

You might want to remove the belt(s) and manually check all the pulley bearings for play or noise.

Can you hear the noise from the tail pipe?

Check the condition of the heat shields along the exhaust system - look especially for looseness and vibration, of course.

I concur with RoadRunner, pull the belts one at a time - my guess is that almost new alternator has eaten its bearing or slip ring and the rotor is machining away the stator.

Thanks guys, all good things to try. I’ll see what I can look at.

Get hold of a mechanics stethoscope

Or try a few feet of garden hose.

avoid letting loose clothing, long hair, etc from becoming involved with moving parts

Very good advice.

Sears Sells Craftsman Stethoscopes For $15 Or $20. It Behooves One To Make A Purchase.

My stethoscope isn’t Craftsman, but it really amplifies sounds (in stereo!). It’s a nice addition to any tool box and I like to see people’s reactions when I put on my “Doctor Motors lab coat” and start probing under the hood. It can “go where no hose has gone before”.

Yup saw one on their website. I’ll drop by my local sears (Across the street from my office) and pick one up. Sounds like a useful tool for a lot of stuff.