The prop shaft components can't be "greased". Unless you hit something to damage something on the propshaft, I doubt this is worth looking into.
This leaves the rear diff and the wheel bearings. Your cars are of an age where a wheel bearing could be going. There is a "possibility" to isolate the wheel bearing. I say only a possibility because it won't necessarily eliminate it. When you are going at a speed where you can clearly hear the whine, make a moderate sweeping turn. In many cases, if it is wheel bearing related, doing this while maintaining speed will change the pitch or even presence of the whine. If it does, you can be fairly sure it's one of the wheel bearings. Which one will be harder to figure out.
Our rear diffs get very hot under normal extended running. However, if there is something wrong with the diff that would cause a distinct whine, it is likely that a tremendous amount of heat will be generated. Under normal circumstances, it will be hard to keep your hand on the diff casing, but still do-able. If there is something wrong with the diff, this will be nearly impossible - VERY hot. You can also check the fluid for being overheated. Burnt hydraulic fluid will have a distinct smell (apart from the already sulfery smell that's normal).
CV joints going bad won't generally "whine". You'll get vibration upon acceleration.

 

I have a fairly good idea which wheel bearing it could be. I had to replace it awhile back and I dont even wanna say how it was done, Ill do some sweeping turns and keep my ear out on it. I got 120k on my01 now.. so yea... its been around the block. I do know the diff fluid is due for a change too so that could be a culprit, Im flushing this weekend as well so thatll narrow it down some I think.

 

[QUOTE=xviper,Nov 22 2005, 05:10 PM]The prop shaft components can't be "greased".

 

RandyP, that sounds EXACLY what im dealing with here. There is grease splattered all around where the propshaft and transmission meet. What would be the odds that that would cause the noise. And if it is the transmission bearing you are talking about how detrimental is it?

 

[QUOTE=RandyP,Nov 22 2005, 04:28 PM] Hey, the front joint on the prop shaft is like a CV joint.

 

So where to start diagnosing the problem in case of wheel bearing or driveshaft bearing, etc.?

 

A wheel bearing getting worse will whine more and more (louder and louder) till it starts to just howl. Drive beside a tall wall with that sides window down and you can easily hear the sound bounce back. Do the same for the other side. Or you can have someone drive next to you to listen. However, you have to know what your are listening for.
A propshaft or halfshaft CV going bad will begin to put out vibrations more and more. A mechanic can inspect them and determine the amount of "play" or lateral movement that is normal or abnormal.
With any of these things, you will never know for sure till the bad component is replaced.

 

Xviper... i think you just solved it for me. Of course as you said, I wont know for sure until I replace the suspect part. But I feel 90% certain that it is the wheel bearing. Will post results when I have it replaced.

 

All I know is that the prop shaft was spraying grease and I let Honda "repair" the problem with a band clamp. 30,000 miles later, I do a clutch replacement myself and notice oil coming from the prop shaft to transmission flange. I took the joint apart and replaced the grease.

 

A wheel bearing getting worse will whine more and more (louder and louder) till it starts to just howl. Drive beside a tall wall with that sides window down and you can easily hear the sound bounce back.

Xviper, I have these symptoms. Do you have a ballpark idea what this will cost to replace by Honda?