PlotPoint

1st Gen LS 400 ('94) - Low Mileage (100K or so).

Hearing a fairly loud (can be heard while driving) creaking, popping sound on the front driver's side. It's similar to the sound you would hear if you were standing on loose wooden floor boards and shifting your weight back and forth. If the floorboards were metal, that is. Today, when I got out of the car (and my 130 lb. weight was off it), I heard that 'creak/pop' sound on the front left. I was able to duplicate that sound by getting in and out of the driver's seat. Not every single time -- but often enough. How fast I am driving does not seem to make any difference. I tried shifting suspension from high to normal (car has air suspension) -- no difference. I do notice when backing up that the creaking seems more predictable and slightly louder. A few times I have been able to press on the driver's side bumper to make a 'crunch' noise. This creaking/popping noise has gone away for long periods (several weeks -- twice, in fact) and it is now back.

When this first happened, I took it to a mechanic, and of course it would not make the noise the entire time they had it.

Any ideas? Front suspension is original, with only the strut rod bushings having been replaced. Btw, in case this helps, the first time I heard the noise I had just made a sharp left turn from a stop sign. I kind of goose-ed it on the turn (looking to get out of the way of an oncoming car). Right after the turn, I heard a kind of metallic 'rattle', as if something had come loose and or was metal tearing, then the creaking/popping noise continued after that.

It definitely does not sound like something I should continue to ignore, but at the same time the car drives the same (other than the noise).

oldskewel

iTrader: (1)

I had a clunking noise, much less frequent than yours. It would usually happen only once per drive. Yes, weird. After living with that (failing to find a problem), I finally found that I could make it happen at will by making low speed tight turns in alternating directions. E.g., a tight left turn ... clunk. More left turns ... nothing. Tight right turn ... clunk. More right turns ... nothing. Tight left turn ... clunk. This all makes sense after finding the solution ...

It ended up being 4 nuts holding the main engine crossmember in place. They just loosened up over time. The clearance holes for the bolts are oversized, and the clunking was the whole assembly sliding slightly to the left or right from the inertial force of turning left or right.

If you go under the car, it will be the big Aluminum casting that crosses under, going from the left to right sides, approximately under the rear of the engine. There will be 4 main nuts (maybe bolts?) holding it in place. On my car, those nuts were noticeably loose. So you could try just putting a socket on them to see if they turn. If they do, look up the right torque value and maybe also use threadlocker. Incredibly easy fix if this turns out to be your problem.

For good measure, I quickly tested all other nuts/bolts I could access down there (just seeing if they would move with a medium amount of torque applied) and nothing else was a problem.

Losiracer2

check your upper control arm and lower balljoint for any tears in the boot. If there is a tear, chances are grease is all dried up and dirt has gotten in and compromised the joint.

VolumeToo

Creaking ship will almost certainly be your front sway bar bushings, and luckily they're a breeze to do. Some people call them D bushes because of their D shape.

Remove two bolts, pull down the U-clamp, remove bush, pack with Toyota Lithium Soap Base Grease (which you'll already have bought for your caliper slide pins ), re-fit. Might be a good idea to renew the bushes, as chances are the grooves that retain the grease will have worn down some. (The newer ones might have a diamond pattern embossed in them.)

At this point somebody will probably argue - which is fine - but this is a fix that worked for me and stayed fixed.

Losiracer2

one way to rule it out is to jack up the car and lift the wheel up and down. That'll tell you if its a balljoint since you'll notice some vertical play. If there is some lateral play, it could be a tierod if the wheel has side to side slop from 3 & 9 o'clock positions. If you have 12 and 6 o'clock play, it could be a bad wheel bearing.

YODAONE

Do you have any images of the studs, bolts and or nuts holding the engine cradle?

Recently posted about transmission to chassis crossmember boltsthrough hole 16mm with 10mm bolt!)

https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/872848-transmission-crossmember.html


Any estimate on the tolerance between bolt or stud and engine cradle mounting through holes?

Amskeptic

The engine cradle is referred to as the crossmember in the manual. Each hole responsible for a mounting bolt is 15mm. The difference between the bolt diameter and hole diameter is to allow for precise placement of the crossmember on the body. This affects tracking, toe, and even engine-to-driveshaft alignment.
Colin

oldskewel

iTrader: (1)

Agreed with the above. Although perhaps in addition to "precise placement" it simply allows the thing to be assembled at all with the assembly line requirements. Not sure.

Yodaone - I do remember your thread on that. Very interesting. I remember reading it with nothing really seeming surprising. So mine probably looks similar to yours, of course considering the difference in years.

BTW - I became aware of the loose crossmember screws being the cause of clunking from someone else on here who posted that - AFTER I had been hunting high and low everywhere for the source.

From the OP's description here, I'd say loose crossmember screws are not the most likely cause (and the other suggestions above are likely better), but this one is so easy to miss and also so easy to check, so it's worth inspecting. I this is a problem, the screws will literally be loose - so you can just put a socket on them and turn. If it is not the problem, you'll know immediately, when they don't move at all (like every other nut and bolt down there).

YODAONE

Ok. Do you know bolt shank or thread diameter?
The transmission cross member link was provided to show what happens when a six mm disparity between a bolt and it's through hole.

Certain fasteners used on our cars were designed more for mass production.than close tolerance fit...so room for improvement.

My guess is if such noise from a crossmember shifting, then probably too much bolt-through hole tolerance.

Perhaps you can agree that only the.underside of the head of the bolt clamping the crossmember that is subject to; engine torque, is an integral .part of steering, suspension and braking, is not an optimum solution

Case in point is the transmission crossmember...

If the bolt shank is threaded it's entire length, then simply replacing with an unthreaded shank (for length of through hole) could reduce tolerance (and threads fretting and cutting into aluminum crossmember)....but not much.

Subject to avaiability, a larger head diameter (increased clamping area) would benefit the existing scheme.

A custom shoulder bolt is an option.

If unsure of tolerance then I may remove and inspect one on mine.

It is 0 Fahrenheit so hope someone comes through

Meanwhile, thanks for your reply....

dicer

I've had 2 gen 1's with creaking and it was upper control arms.

oldskewel

iTrader: (1)

I've found a good way to isolate suspension problems (worn out, loose joints, etc.) is to jack the car, support on stands, get under there.

Then have a helper kick the tire (boots on, bottom of the foot to prevent injury) while you put your hand on each joint (one hand touching on the metal on both sides of the actual joint). When you find the loose one, you will feel the slight movement in your hand better than you can see it. Everything will vibrate from the kick, but your hand will feel any difference across both sides of the joint. If there is no difference, that's a tight joint. If something is loose, one side will move more than the other and you will feel it easily.

Then to confirm, see how the other side (passenger side in this case) feels for the same joint. This won't find everything, but if your problem is so bad that getting in and out of the car can sometimes make it happen, this might work.