"rumbling" Type Vibration On My Friends Ls 93'

[90LS400Lexus]

Yeah... I hope it is just the tires. I will do that with the wheels as well. The tires are Michelins... I do not recall what grade/type. As I think I mentioned in another thread, the tires are about 5 years old, so that may explain it. <_<

Sure is a helluva lot better than replacing a driveshaft do ya think? One more thing you can try until it's time to get new tires - rotate the one tire they couldn't balance to see if the vibration changes. Say from front to back? BTW what tires are you running? And what pressure are they at? You could try messing with the pressure as well.

[nc211]

90, how many miles do you have on your car again? Know how long it sat before you bought it? You might just have a flat spot from it sitting too long. If that's the case, filling it up close to max psi per the tire's rating and taking a highway run might round it out. I know on my wife's mazda, with those low profile 18' soft rubber tires, it flatspots over night! but smoothes out after about 5 miles. Normal psi should be set to the car's recommendation, with I think is on the inside of the glove box, or armrest, or driver's door jamb.

Tires do make a huge difference on these cars, so much so it's almost rediculous. I tried a pair of continentals once, for 1 day, and returned them for Michelins.

Good luck, and let us know how it goes!

[90LS400Lexus]

Thanks NC. The car has nearly 209K now. I have only put about 250 miles on it since I bought it. I think the car must have been driven little over the past 5-6 years, because the car had 201K in the year 2003! So, thats about 8000 miles in 4-5 years! Tires on there since 2003. As mentioned, I hate to get shed of the tires, because the treads are still excellent. I guess Michelins are very good tires as far as treadwear goes, but I am sure any tire could get flat spots from setting alot.

90, how many miles do you have on your car again? Know how long it sat before you bought it? You might just have a flat spot from it sitting too long. If that's the case, filling it up close to max psi per the tire's rating and taking a highway run might round it out. I know on my wife's mazda, with those low profile 18' soft rubber tires, it flatspots over night! but smoothes out after about 5 miles. Normal psi should be set to the car's recommendation, with I think is on the inside of the glove box, or armrest, or driver's door jamb.

Tires do make a huge difference on these cars, so much so it's almost rediculous. I tried a pair of continentals once, for 1 day, and returned them for Michelins.

Good luck, and let us know how it goes!

[nc211]

Yeah, I'd say you might have a flat spot.. I'd possibly up the psi on the tires to the max setting on the tire's sidewall and go for a 30 minute highway run to see if they'll round out, then set back down to normal. My folks spend 6 months in Oklahoma, and 6 months in S. florida. Everytime they return to one of the houses, the cars are flatspotted badly. Pops ups the psi to max setting on the tires and hits the highway for about 45 minutes...fixes them every time....

[eatingupblacktop]

<br>Well,

I went ahead and made an appointment @ my local Lexus dealer to have my

car checked on Tuesday. He said they would check it out for $35.00, so

I figure it would be worth the $35, rather then me to replace this and

that.<br>

<br><br>

You know if you read enough of this forum, it gets to be hard to settle in for a nice relaxing cruise because your ears are open wide for most of the trip. 90LS or should it be 91LS, how did you make out at the dealer? I'm asking because, I think I'm beginning to detect a slight vibration at about 60 kph. Ealier this summer, I drove for about half a mile with the prk brk on. The vibration grew stronger the faster I went until I had to stop to find out what it was. I totally forgot about that until now. I'm wondering what all that vibration might have affected? Soon as I get some time, gonna have to do some of the tests that everybody's posted on this thread.<br>

Update. Whew! One tire reinflated to 33 lbs from 28 and another rebalanced and the LS is the old smoothy she was meant to be. Started with the easy stuff and am I glad I didn't have to go any further. FYI, coasting in neutral - no change. Driving over different surfaces - noticeable change.

[90LS400Lexus]

Hmmm. Interesting. I will try that tire inflation pressure on that LR tire and see what happens.

Update. Whew! One tire reinflated to 33 lbs from 28 and another rebalanced and the LS is the old smoothy she was meant to be. Started with the easy stuff and am I glad I didn't have to go any further. FYI, coasting in neutral - no change. Driving over different surfaces - noticeable change.

[kmpdd]

Take a look at my attachment.... see where I've circled and arrowed? That is the 3rd mount to the differential, which attaches directly to the underside of the car. It has rubber rings to insulate it from the car. I was going to replace these on mine, as they were dry-roted pretty badly. I'm thinking that when these begin to go, the rear differential will vibrate up against the underside of the car very quickly, creating a hum/drone noise. I replaced the rear diff mounts on mine, and made a nice, tight difference in things, but never got to these little rubber rings. I was going to take this exact same drawing to the dealer and buy new rings, as they can't be that expensive "they're not all that big". It's very easy to do, just one bolt holds it up...undo the bolt, pull the old ring(s) out, put in new one(s), and reinstall the bolt.

I have a 90 ls 400 with a "droning" noise that can be heard from 65-70 mph. The car is extremely smooth otherwise. The sound is definitely coming from the back. It sounds like differential mounts could do the trick, but what about those rings, are they something that can contribute to this sound? How many differential mount are there? thanks

[90LS400Lexus]

Not sure, but I was terrified that was a problem on mine, but they say its the tires.... we will see.

Take a look at my attachment.... see where I've circled and arrowed? That is the 3rd mount to the differential, which attaches directly to the underside of the car. It has rubber rings to insulate it from the car. I was going to replace these on mine, as they were dry-roted pretty badly. I'm thinking that when these begin to go, the rear differential will vibrate up against the underside of the car very quickly, creating a hum/drone noise. I replaced the rear diff mounts on mine, and made a nice, tight difference in things, but never got to these little rubber rings. I was going to take this exact same drawing to the dealer and buy new rings, as they can't be that expensive "they're not all that big". It's very easy to do, just one bolt holds it up...undo the bolt, pull the old ring(s) out, put in new one(s), and reinstall the bolt.

I have a 90 ls 400 with a "droning" noise that can be heard from 65-70 mph. The car is extremely smooth otherwise. The sound is definitely coming from the back. It sounds like differential mounts could do the trick, but what about those rings, are they something that can contribute to this sound? How many differential mount are there? thanks

[90LS400Lexus]

Well, depending upon my cars engine/tranny temperature, mine has that slight "hum" noise when I get to a certain place on a road every time I drive it, if its the first trip out for the day. Its a slight incline where I go about 35mph and I lightly accelerate.... it puts out a slight humming/whistling noise. After the cars been driven, that goes away. I still wonder if maybe thats not part of my problem, despite what the Lexus tech said?

I'm thinking that when these begin to go, the rear differential will vibrate up against the underside of the car very quickly, creating a hum/drone noise.

[eatingupblacktop]

Well, depending upon my cars engine/tranny temperature, mine has that slight "hum" noise when I get to a certain place on a road every time I drive it, if its the first trip out for the day. Its a slight incline where I go about 35mph and I lightly accelerate.... it puts out a slight humming/whistling noise. After the cars been driven, that goes away. I still wonder if maybe thats not part of my problem, despite what the Lexus tech said?

I'm thinking that when these begin to go, the rear differential will vibrate up against the underside of the car very quickly, creating a hum/drone noise.

Have you noticed any correlation between the humming noise and the vibration? You say after the car's been driven the noise goes away. If that's the case, rubber rings can't be the cause. Deteriorated rings stay deteriorated and I would think the noise would be continuous. Have you checked for any intake leaks that seal up once the engine reaches operating temp?

[90LS400Lexus]

No, the vibration continues and no worse when its making that whining noise. I have had other cars in the past that has made this same noise, but never was able to put my finger on it. It only does it that ONE time at that very same location on that roadway on my first trip out for the day and only when its in "overdrive" and when lightly accelerating.... sometimes it will kick out of OD and I think the noise goes away. I do not think there is anything wrong with the transmission because it shifts flawlessly through all gears @ all times. Fluid level is full and very clean.

Not sure about intake leaks? I do not even know how to check for that. The engine does run smoothly and quietly however, with no oil leaks or oil burning... yet anyway. LOL.

Thanks again!

Have you noticed any correlation between the humming noise and the vibration? You say after the car's been driven the noise goes away. If that's the case, rubber rings can't be the cause. Deteriorated rings stay deteriorated and I would think the noise would be continuous. Have you checked for any intake leaks that seal up once the engine reaches operating temp?

[eatingupblacktop]

"Same place same time", sounds like you're passing through the Twilight Zone? When you mention it drops out of O/D (normal on a grade and under acceleration) and you lose the noise, it could be because the engine is now revving higher and the tranny's running a different gear. What would happen if you ran the "Twilight Zone" in 3rd at the same revs you're doing when you notice the noise in O/D? Just trying to isolate the noise to either the engine or the tranny. Any chance it could be a resonating heat shield or something loose under the hood that tightens up when it heats up?

[dery45]

I posted this on the other Lexus site and got some good replies, but wanted to try here as well for more info.... I was told it could be mounts, tires, tranny fluid, etc.

My friend is experiencing another potential "problem" with her LS400. Between about 35-55 mph, it has a rumbling type vibration that can be felt slightly through the steering wheel. Ive driven the car... its not bad, but where the car is otherwise so smooth, its bothersome. The sound is not loud, but it seems to "drum" in your ears. Also, not sure if its linked, but when the temps are cold out, and the engine is not fully warmed, when the car is in 4th gear and at a lower speed under light acceleration, there is a slight whistling/humming noise coming from the car. My old 90' LS400 had a similiar vibration and it turned out being the tires, so it may be the same case with this car. OR, I was thinking that vibration may be something like an engine or transmission mount? I am actually having the same problem on my car.... !!

Lastly, on acceleration from a stop, there is a slight hesitation just after the car starts out. It has a new air filter, so I do not think thats it... I am thinking maybe the throttle body needs to be cleaned?

Any advice appreciated!

I hope I provided enough info... if more details needed to help out, please let me know and I will relay more info if I can.

You have the same problem with my 96 LS400. I took it to my friends transmission shop and found the rear transmission mount is gone bad. The mount is on order so I can't say if this will solve the problem. But before you run out and buy new tires I noticed you mentioned reving the engine while the car is in parked, have you tried that yet? If not try it, leave the car in parked and run the RPMS up to about 2K to 2.5 RPMS, listen and see does it hollow sound comes and goes. If it does it's not your tires or your rear end since your car is not moving. It has to be related to mounts or something like that. I hope this helps. Once I get my motor mount installed I will post the fix.

Brad

Problem solved!!

Reverbitation, hormonic sound. It turned out to be the rear transmission mount. I purchased the mount form discounttoyotaparts.com, for about $44.00. My partner put it on. It not only solved the hormonic vibrations but also greatly inproved the shifting of the transmission, everything feels realy solid not - no jerking around or weard feeling down shifts. In order to check the mount the transmission must be pushed up on with a lift of some sort. The bount is rubber, so if you see it seperating it needs to be replaced.

Brad

[tomyy]

Well, I went ahead and made an appointment @ my local Lexus dealer to have my car checked on Tuesday. He said they would check it out for $35.00, so I figure it would be worth the $35, rather then me to replace this and that.

So what did the dealer say?

I have the same problem, vibration that seems to be towards the front.

I don't know if the tires need to be balanced? I check the tire pressure and that's not it.

[dery45]

Tomyy

You might need to make a determination if the vibration is only present when your car is moving. First, while driving note the RPM when the vibration is most noticable. The try tolding the trottle in the same RPM range while the car is in park. Be patient and listen and feel carfully. Is you notice that you have the same vibration while your car is in park then you have possibly eliminated anything to do with tires, rotors, drive axle, rear end etc.... I would focus on something around the engine or the transmission. As I mentioned, my problem was the rear transmission mount.

Good luck,

Brad

[90LS400Lexus]

The dealer said that it was the tires... one was out of balance and there was something wrong with one of the wheels and it would not balance. Tech said that when I put on new tires, use the spare in the trunk for one of the regular wheels.

So what did the dealer say?

I have the same problem, vibration that seems to be towards the front.

I don't know if the tires need to be balanced? I check the tire pressure and that's not it.

[eatingupblacktop]

The dealer said that it was the tires... one was out of balance and there was something wrong with one of the wheels and it would not balance. Tech said that when I put on new tires, use the spare in the trunk for one of the regular wheels.

So what did the dealer say?

I have the same problem, vibration that seems to be towards the front.

I don't know if the tires need to be balanced? I check the tire pressure and that's not it.

First time I've heard of a wheel that can't be balanced unless it's been banged or warped, or was manufactured out of round in the first place. Did he offer a reason why it can't be balanced? A wheel that's been previously balanced and has suffered no damage can only go out of balance because of tire wear. Usually the weights will take care of that unless the tire itself has something wrong with it. My suggestion - ask him to take a tire from a wheel that has been balanced and put it on the suspect wheel. Then you'll know for certain if the wheel is the problem.

[eatingupblacktop]

Just remembered something else I once did. I was balancing a wheel on one of my Sciroccos I used to own; didn't like the fat weight the Tech put on one of my nice wheels, so we broke the seal and first rotated the tire 180 degrees, then 90 degrees on the same wheel. Sealed it, balanced it with a weight that was 1/10 th of the original. Now in my case, the first balancing would have worked, I just didn't like looking at all that lead on my rim. In your case it might be worth trying to see if you can get a problem tire/wheel balanced correctly.

[tomyy]

It seems it was the tire pressure after all. I have a slow leak in one of the front tires.

How do those "seal a flat," things work? I heard their bad for tires, is that a myth?

[90LS400Lexus]

He didnt say... he just acted as if the wheel was defective and said I had no need to fret. He said if I could live with the vibration then it would be OK until I got new tires, but since the tread was still good, he would not recommend new tires now. If I get new tires/change out wheels and it remains... back I will go, but a little more unhappy. <_< It may be the tires, but I have a deeper feeling that its more than that.

Whats so eerie is that the vibration is IDENTICAL and I mean IDENTICAL to the vibration my other LS400 had. If I were to be blindfolded and you took me for a ride in my current LS400, I would think I was in my old LS400. Its the EXACT same vibration and at the EXACT same speeds. So strange. On that car, when I had it checked, they said that the tires were "cupped". We linked it to poor alignment, because when I had rear struts installed... that shop did not align the car, which I later found out they were supposed to. The vibration started about 1000 miles after the new struts and only got worse.

The dealer said that it was the tires... one was out of balance and there was something wrong with one of the wheels and it would not balance. Tech said that when I put on new tires, use the spare in the trunk for one of the regular wheels.

So what did the dealer say?

I have the same problem, vibration that seems to be towards the front.

I don't know if the tires need to be balanced? I check the tire pressure and that's not it.

First time I've heard of a wheel that can't be balanced unless it's been banged or warped, or was manufactured out of round in the first place. Did he offer a reason why it can't be balanced? A wheel that's been previously balanced and has suffered no damage can only go out of balance because of tire wear. Usually the weights will take care of that unless the tire itself has something wrong with it. My suggestion - ask him to take a tire from a wheel that has been balanced and put it on the suspect wheel. Then you'll know for certain if the wheel is the problem.

[4.0 LS TECH]

It seems it was the tire pressure after all. I have a slow leak in one of the front tires.

How do those "seal a flat," things work? I heard their bad for tires, is that a myth?

Not really bad for the tire. But most of those sealers are bad for the wheel. that stuff is actually pretty corrosive. it eats you wheels from the inside out. just go to a tire shop and have it patched.

[cardona6569]

Hello:

The humming noise could be the PS Pump, like in my case. My mechanic noticed, but with that noise it can go a long time, it is typical in these cars and the Mitsubishi, they more or less use the same type of PS PUMP. The Mitsubishi sounds even more than the one on the LS, like a growl.

[cardona6569]

Hi:

The humming noise coudl be the PS PUMP, which is typical because of the wear on these cars after a lot of miles/years. But besides that It should be no problem for a lot of years. Mine has it. Mitsubishi cars do get it in their PS Pumps but it sounds horrible compared with the LS which is just a little noise really

CPR