I noticed that my LS has always made somewhat concerning grinding noises from the engine bay. You can't hear it with the doors closed and windows up. However, if you're running the car, and say, checking the tranny fluid level, then you can clearly hear it.

Now, I don't have much experience with cars, but I believe it's one of the pulleys that's going out. I highly doubt it's anything to do with the engine itself; the car burns 0 oil at 200k and runs great. When I replaced the serpentine belt a month or so ago, I noticed some slop too in the radiator fan.

I've uploaded a video. The grinding is not quite as loud on video as it is while standing next to the car. But I can say that a new car's engine while running doesn't make these noises. Is this a cause for concern? Should I replace the pulleys? Do they often go bad? How hard is it to replace a pulley or two?


Edit: I read that it could be the water pump's bearings that's going out? Could that be the case? The last guy who owned the car DIY'd the timing belt replacement but he openly admitted that he didn't do the water pump while in there...

Get a cheap stethoscope and probe around, it could be any of the bearings up front. I would not run it too much till you have it sorted out.

Hey OP, sorry about your problem. I hope you get it figured out. Now I don't mean to hijack your thread but I have a grinding noise that only happens when the car is moving. It tends to happen more often when I turn (even switch lanes) but occasionally when I'm driving straight too.

It has never actually concerned me because there doesn't seem to be any actual problems and it sounds like something metal or maybe rust rubbing on other metal. Either that or there's like a foreign object that moves around and possibly touches a pulley or somethinc.

What does it sound like? It sounds like a piece of tin dragging on a semi-rough surface. Just a mild grinding type noise but I can tell it's nothing major unless it could be a bearing that has some dirt in it?

I'll take another look around to see if I can find the problem.

I almost forgot. I haven't done the brakes on this car yet and I can see that there's possibly a small stone in between both front brake pads because I can see small lines etched into the rotor. In my mind, that's probably the problem but I would like a little input.

Remove the serpentine belt and spin all the pulleys individually. That's the easiest way without dangerously sticking your hands next to moving parts and causing injury.

I replaced the bearings in my tensioner and idler pulleys for only $14. There's a thread on here about the bearing sizes somewhere that I referenced and just found the on Ebay. I went with some NTN bearings, hoping that they're genuine but who knows, they're still working 8 months later so I think they're the genuine ones.

My guess is the "fan bracket." Search this site for that. It's a cast Aluminum piece that holds the bearing for the fan, and the bearing usually fails between 150 and 200k miles. If that's what it is, and you've been thinking about doing a timing belt job, now is the time, because the fan bracket is in deep.

That's always a good and quick troubleshooting step. The engine should idle just fine with the serpentine belt removed. So remove the belt, fire it up and confirm that the sound is gone. Pretty certain it will be, but it's an easy test to do.

Since the OP's problem is when the engine is sitting there idling, and yours is only when driving, it's pretty unlikely that they are related at all. You might want to start a new thread.

If I were a betting man, I'd be putting down money on this post.

16307-50011

that's the part number, not the odds.

Here's a youtube video of a failed fan bracket. Sound is similar to OP's, but this one is obvious since the fan can be seen wobbling all over the place. When mine failed, it made a weird fluid squealing noise, like I expected to see liquid sprayed around when I looked into it. But that was just the noise the bearing made when grinding away, since I caught it pretty early, I guess.