azari

In my '91 LS400 with 76k miles, I have a very small droaning/whining noise when I'm doing 60-65 MPH, and the noise is heard only in that speed range and it comes and goes with throttle response (audible when pushing gas, goes away when not pushing). However, it does not have any kind of a vibration. Again the noise is very low in volume and definitely can't be heard if there is a conversation with someone in the car or the windows are rolled down; so you'd have to sort of look for it, and to somebody who just sits in the car it's not even noticable (i know it, because I look for it). My guess is that the car is at its developing and beginning stages of having a bad differential. However, I heard from some people that "a little" humming noise from gear mesh is completely normal. But would that be true in an LS400??? What do you guys think? At that speed range, inspite of the whining noise being very low, that's the only noise that can be heard in the interior (again, if one listens sort of carefully).

Also, what are some of the solutions? could I take it to a dealer, and maybe ask for adjustments on the differential and etc? is there such adjustment to eliminate the problem/noise? I thought the LS400s were bullet-proof, what's the deal here??!! (especially a diff problem ). Anyone ever experinced any differential problems???

thanks very much to all

ragabnh

I have a 1990 LS with 155000 miles, I have the same problem, however I noticed that when you step on gas pedal this noise occurs and when you release it, the noise will disappear, that is why I am not sure if it is the diffential or something else.

SRK

You may have identified the differential crown and pinion noise. If the sound is "musical" in tone, without a growl to it, it is probably normal. I can't say that I have found it in my LS, but to some extent all diffs make the sound. It is a normal product of a hypoid gear set. As long as the noise remains "musical", everything is fine. The change between drive and coast is a big clue that it is the diff.

Lex Tech

I don't recall ever seeing a diff going bad in an LS before.

Here's something you can check/try to do yourself.

1. If you happen to know at what rpms this noise is heard, rev your engine to that rpm to see if you can duplicate it. If it does it then, it's not a diff/driveline problem.

2. While cruising down the road at or around the speed it happens; once you get it to do it, put the transmission in neutral. If it still does it then it may be something in the driveline.

Some early LS drive shafts have been known to go bad. They have a carrier bearing in them right around the foot area of the back seat passengers. Usually if they go bad though the car vibrates quite noticeably.

Something else I've noticed is that the Exhaust system on these cars have dampners on them. If one of them has come off it'll make an odd resonating sound at certain rpms with no vibration...

If it's really not that noticeable though and you can barely hear it. Instead of tuning in to the noise, why not tune into the radio instead?

azari

To be honest, it's a bit disappointing to have to hear that noise in an otherwise perfect running/looking car. But, like i said before, it's one of those annoying things that until you don't know about it, everything is fine; but once you do hear it, you look for it the next time you drive the car to see if it's there or how much worse it's gotten. I am pretty confident that I can't duplicate the noise through the procedures you gave, and I can hear from the back area when I lean back to locate the noise (comes from bottom rear).

Now get this: the only thing that makes me think it may not be the differential is the fact that I can still hear the same noise/whine (or a very very similar whine) at almost all other speeds, but this time the whine seems to come from the front of the car (engine or tranny) as oppeosed to the back (which occurs at 60-65 MPH). It seems as if the noise starts out from front end, and as soon as I reach 60-65 MPH it immidiately gets transfered to the back and can be heard from back. This is the only thing that makes me doubtful about having a bad differential.

Wide LS

I have a 93 and I hear the same noise too, when I accelerate I hear a noise but I hear it when i go over 40. It sounds like a very low whinning noise, but it's so low that you have to be very quiet and have the windows up with the radio off. I started hearing this noise after I install my two mufflers, but the pipes i did not touch, I just replaced the stock mufflers. I think it's normal though because I've been hearing this noise for more than an year and have had no problems, I'm kind of use to it already I guess. Well I hope this helped

PERRYinLA

Yeah yeah I know this is a very old thread, but to anyone researching this issue and seeing this during a search- the rear transmission mount (called the rear engine mount by the parts dept) could very well cause this.

On my car, it was a droning, moaning or growling noise only upon deceleration, most pronounced between 65 to 55 mph.
As the rubber in the rear transmission mount breaks down, two things happen- the upper and lower metal plates of the mount begin to make contact, and the angle of the driveshaft changes.

Those two conditions will make noises gradually or abruptly appear where before there were none. Perform a search and you'll be amazed at all the problems that a new transmission mount fixes.

2700$oarer

if it drives fine, i think you are just being alittle too picky if it can't be heard over talking? it is an easy fix however and cheap, just turn on your stereo...

PERRYinLA

Well, you have the right to feel that way
and the right to participate in this forum,
(although I don't see how those two would ever coincide).

If your car sounds one way for 100,000 miles, and then suddenly (or gradually) a new noise appears, that means something has changed, and you might wanna investigate what it is, before it gets worse.

In my case, if I ignored that noise, the transmission would sag more and more, increasing the stress on the driveshaft and differential and making it more likely to fail.
That's a much bigger repair bill than a $60 transmission mount.

Of course, you can ignore it and turn up the stereo if you don't care about your car, or what happens to it, but I didn't think there'd be many of those that would join ClubLexus. Or take the time to read this thread, or respond to it.

Mikenbon

I for one am quite pleased to know this information as I have the same noise. I just purchased a 96 gem and I'm going through it to determine reliability. To go to a mechanic with this sort of thing is like burning money. I'm very thankful for this forum!