Mrstewart

I've recently ran into a problem I cannot figure out.
When driving my car between the speeds of 40-60mph, I hear a loud whining noise. The noise goes away when I hit 70-80mph. I have a 1990 Lexus LS400 could someone please help me with figuring this problem out???

dicer

Sorry I don't hear a thing. But can guess, maybe its a bearing going bad?

Mrstewart

Thank you. I have a video but the format won't upload. I didn't know bearings would whine

Amskeptic

Please . . .

Bearings can whine. Not engine bearings, which would knock if they were unhappy, but alternator bearings, water pump bearings, wheel bearings, etc.

In your case, since it appears to be vehicle speed related, we can guess that your center support bearing on the driveshaft might be the culprit. Does the noise "go away" or does it, more likely, *get masked* by increasing ambient noise as your speed increases?
Colin

dicer

So what is the "please" for? I never said main or rod bearings. And since I have in the past worked for over 10 years on industrial engines as a job maybe I know a small bit of how engines work?
I'm sorry I didn't specify wheel or other frictionless bearings used on the vehicle.

And how loud and what frequency does a main bearing knock at when it goes bad?

Mrstewart

Thank you. Could you tell a way this could be fixed or tested?

Amskeptic

I was not responding to you, dicer. I was specifically responding to Mrstewart who wrote: "I didn't know bearings would whine".

Now that we are here, is your question about volume/frequency of a main bearing knock a real question? Because the answer is a double answer, the rpm of the crankshaft and the "resonance" of the block . . . as you know.
Colin

Amskeptic

There are a number of ways to attempt to narrow it down, but based on your questions, I think it would be safest and quickest to take it to a shop for a diagnosis/test drive.

If you have initiative, you can try to verify if the sound actually does go away at higher speeds versus merely gets masked.

You could chock the car securely at the front, support the rear suspension carefully and remove the wheels and run the speedometer up to your target speed while listening with the driver's door open, but I am not going to recommend that to a neophyte, if you are indeed a neophyte. You just have to attack the sound with questions, does it get louder under load, under coasting, when cold, when warm, does it emanate directly from underneath the center of the car, or perhaps the rear of the car, right side or left side, etc, so you can localize the offending part.
Colin

dicer

Main would not make much if any noise. I didn't say rod.

Amskeptic

Why are we having this conversation?

You didn't say main or rod bearings. I wasn't communicating with you. I mentioned to Mrstewart that yes bearings can whine, but I specified to him that I was not talking about engine bearings.

And here we are wasting time while I try to both explain to you that I was responding to Mrstewart, and now am attempting to clarify what the hell I was referring to. So, FYI, main bearings can make all kinds of noise, so can rods, but this is NOT relevant to Mrstewart who must think the internet is some kind of strange place by now.

Elless400

Do they serve popcorn at Club Lexus? I'm still new here...