Moonlight9

Hi, all. I've lurked this forum for a few years now, but this is my first time actually contributing. I'm the proud owner of a white 2000 LS. 177k miles and counting on the odometer. I have a strange issue that I can't find anywhere else on this forum (or the web for that matter).

My issue:

Mostly revving above 3k RPMs or so, a high-pitch 'whine' develops. It sounds kind of like air quickly rushing through an opening. You know the iconic 'wind rushing through a poorly fastened fabric flap' sound? Like that. Sorry for the poor description.

It first appeared about a hundred miles after I replaced the fan pulley bearing (I did the work myself, OEM part). It will randomly happen below 3k RPMs, and then sometimes it won't happen at all. 90% of the time it will happen at 3k+ RPMs though. I've put about 15k miles on the car since this noise appeared (it is my primary vehicle right now).

My first suspicion was that I botched the fan pulley bearing job somehow, but the actual bearing doesn't appear to be the culprit and to be honest it really doesn't sound like a bearing. Then I suspected that air got trapped in the cooling system when I removed the radiator hose to access the fan bearing. So I had the radiator replaced (needed to happen anyway) and the cooling system completely flushed. Noise is still there, same as before.

Other things to note:
- It doesn't affect actual performance in any noticeable way.
- Temperature doesn't make a difference.
- The noise is NOT reproduced by putting the car in park/neutral and revving the engine.

Ideas? Sorry for the long-winded post. You guys are kind of my only hope right now, as I live in a small town and the nearest proper Lexus tech (dealer or indie) is located more than a hundred miles away. There are a few techs in my town but they are not the kind of mechanics I would trust to diagnose & fix a car such as an LS. I am reasonably competent when it comes to doing my own work; I've replaced the engine mounts myself, as well as several smaller jobs. I don't really have the time or resources to start blindly replacing parts, though. So here I am.

Thanks so much for all of the help, guys and girls!

YoshiMan

Try this, just a suggestion... Poke around the intake piping in front of the throttle body, and see if there is a break or crack in it somewhere. I had a friend once with a Jeep wrangler that made this high pitched screaming banshee sound, and it turned out to be a sizable crack in the intake piping that was whistling under high engine loads.

Is that what it is? Probably not, but It wouldn't hurt to check and just make certain

Moonlight9

Interesting theory, YoshiMan. I will inspect the intake area tomorrow morning and report back.

Stroock639

does it sound similar to like a turbo wastegate flutter? when mine shifts at like 3-4000 rpm it makes a noise like that, and my mechanic upon initially hearing it thought it might be a vacuum leak, but another one also thinks it could be predetonation (pinging)

cobalt91

I would look at the clutch on the fan.

Moonlight9

So I examined the entire intake system for any cracks, as YoshiMan suggested. Didn't find anything.

It does kind of sound like wastegate flutter. A vacuum line seems plausible; I have poked around the engine and I haven't found any loose vacuum lines, though. Would pre-detonation cause such a noise? Seems unlikely to me.

I replaced the fan clutch & bearing assembly. The whole thing is one part, I believe? Not sure.

sha4000

iTrader: (1)

Yes it is one assembly.