sand0495

I have identical problems in my 92 SC400 with ~112K miles- a whirring or whining noise that is most pronounced in 1st and 2nd gear, along with a clink/clunk noise when letting on and off the gas, which sounds and feels like too much play somewhere in the driveline. I have been uneasily listening to these noises for about a year now, and am still not sure what they are (dreading having to replace the transmission). However, one thing that I can add is that I also believe the whirring/whining noise is coming from the transmission and not the rear end. The reason is because the noise is present in both 1st and 2nd gear, and it changes pitch as the car shifts from 1st to 2nd gear and vice versa (is most pronounced when downshifting to 1st). If the noise were in fact coming from the rear end, the rear end would not encounter a change in pitch as the car shifted from gear to gear-- the noise would simply be a steady increase or decrease in pitch as the car sped up or slowed down because the speed of the rear end does not depend upon what gear the transmission is in. Rather, because the pitch changes as the gears shift, it would seem to be something within the transmission itself. In addition, I can hear the noise when the car is in park. It is most pronounced when turning the car off. As I turn off the engine, I can distinctly hear the whirring noise changing pitch as the engine stops spinning. Although I am fairly mechanically inclined, I don't know much about auto transmissions. Could this be related to the torque converter, or perhaps a bearing associated with the TC?

cip

I have the same thing. I'm taking mine to the dealer Monday AM (I got a $100 service credit & having them do a thorough inspection) I'll report back then

EDIT: I better edit this before I get made fun of..yes I know 100 bucks @ a dealer only gets me 1 hour of labor.

neurocity

iTrader: (17)

mine does the same thing its a 1997 SC300, I was going to go and do the trans flush thing, but my Lexus guy says they all do that...when the fluid gets hot...

Still deciding what to do.....

john_sc400

As prev stated, I just had mine flushed. No difference.

neurocity

iTrader: (17)

Think it could be the Torque Converter, Way back when I had a 92 Z28 with a 350ci 4spd Auto, after many a doh-nuts with it, it started to whine on accel/decel. but only after it warmed up.

tttp5

iTrader: (1)

Please let us know what your dealer says about the sound. I know dealers aren't a 100% reliable source but the more input the better.

As someone described the sound above, I do NOT get this sound when I am in P, only when the car is put in D and it is on either 1st or 2nd gear.

Very randomly do I get a faint clunk sound coming from the rear center of the car when i let go of the gas or apply the brakes.

john_sc400

(FWIW, I started this thread) (95 SC4, 97k miles)

The car is quiet now, just like a Lex is supposed to be. The fix was simple and relatively inexpensive.

It was the tranny mount. Who'd a thunk it?

$78 for the mount at a Lexus stealer and about an hour to change it, including jacking it up.

The old one didn't look bad when it was in the car. In fact, it didn't look bad when I first removed it. But on closer inspection, I could see that the rubber had compressed enough that the metal pieces from the trans side and the frame side were touching. With the weight of the trans on it, it was a constant metal to metal contact.

Installed the new one and took it for a ride and was treated to silence. The whirr is gone and I didn't even notice the driveline clink.

Of course, this simple fix does lead to some additional questions:
Was some of the noise caused by misalignment and movement or are they normal driveline sounds that are now masked by a good rubber isolator?
Are there still problems waiting to ambush me? Just cause I can't hear them, doesn't mean they are gone.

Further, I did notice some play in the Center Support Bearing and do think it needs to be replaced. Perhaps just the big rubber support. Search for 'center support' to find lots of info. I need to learn more about that.

See this thread for tips on changing the trans mount.
https://www.clublexus.com/forums/sho...center+support
It was easy. You need a floor jack and four jackstands plus a couple of wrenches.

Enclosed is a photo that shows where the old mount had collapsed. The area circled appears to be a gap between the top and bottom, but the place where they are touching is behind the tab so you can't see the metal to metal contact. The gap from top to bottom is about a half inch larger in the new one.

Gotta go for a ride now in my nice quiet car.

cip

John-

Glad to hear yours was just the trans mount. I'm going to change mine even though the dealer says it's OK (cheap insurance either way). Here's what they said about mine: driveshaft estimate $900

I will update once I get the mount changed, but I also found there to be 'play' in the driveshaft as the tech did...not promising. But what was promising is that everything else looked great!! So I'm happy...for now

tttp5

iTrader: (1)

cip - ouch! thats a big sum of money. So are you going to change the mount and then see if the sound goes away and if it doesn't then change the driveshaft?

john- where in CA are you? can i drive my car over for you to have a listen to see if the noise i get is the same as what you used to have before you changed the mount?

john_sc400

Sure. I'm in Costa Mesa. HTH. I'll dig the old mount out of the trash, too,

cip

I'll change the trans mount anyway, yes. I talked w. the service tech today, and he said basically if I'm keeping the car he would recommend replacing the driveshaft. I asked him, what will happen and when if I don't (parts & labor = $980), and he said if the 'clunk' sound gets worse I should replace it, otherwise the only problem at this point is the noise it makes... so it doesn't seem to be an overly concering issue.

I'm going to do more searching though..I would imagine some of the guys here have had to replace the driveshaft esp. w/ the turbo applications.

diablonhn

the growl/whine may be your power steering

to test, put your car in park and then turn the steering wheel back and forth

neurocity

iTrader: (17)

Its the trans mount, I just did mine......mucho better!!!

john_sc400

For sure not the PS. It has its own special growl, just as you describe.

You will notice the commonality through this thread: the noise happens during low speed decelleration.

New trans mount made mine inaudible.

sand0495

I replaced the trans mount on my 92 SC400 as well. It was definitely the problem, and is much quieter now. The trans mount is basically two metal plates sandwiched between chunks of rubber (although the metal plates are oddly shaped). As the rubber gets worn out and compresses, the two metal plates come in contact with each other. It seems that as a result, the normal transmission noises (and engine noises) get amplified and more easily transmitted directly into the interior of the car. The transmission mount is attached to the frame directly under the driver seat, so transmission noises become quite loud.

I agree with john_SC400 that replacing the mount may just be masking other underlying problems in the transmission, but it certainly does help. The strange noises I was hearing. It also seems to have cured the clunking that sounded like slack in the drivetrain. I think that as I let on and off the gas, the clunk I was hearing was the two plates of the transmission mount clunking into each other as the engine/transmission torqued back and forth.

The job was very easy. It took me about 2 hours, half of which was spent cleaning off the greasy frame crossmember before putting it back together (I have a leaky rear main seal). In short, I highly recommend replacing the transmission mount if you have a growling/whining noise on deceleration in 2nd or 1st gear, or if you hear a clunk when letting off the gas that sounds like something loose in the drivetrain.