Make Some Noise About My Noise Issue

[bwarner]

I own a 97 LS400 with 158,000 miles and seemingly it is running very well. There is one small issue that I'm not even sure if it is a problem. Ever since I got the car about 12k ago, it seems to be louder than it should be in the cabin in general. It also seems more noisy on the left (drivers) side. This is especially noticeable under acceleration from a dead stop, and its more pronounced when the engine is cold. Could it be the exhaust manifold is beginning to develop a leak? Once up to road speed and there's no serious load on the car, everything quiets down. Standing outside the car, or if it drives by, its near whisper quiet. The car runs like a top and typical Lexus smooooooth. I just thought this is the way it was - maybe an idiosyncrasy of the make / model. However, I recently purchased another LS400 ('93) because loved my first one, and wow what a difference. This older car is much quieter in the cabin, and has virtually no increase in the engine noise when under acceleration or load. Yet, outside they seem about the same, under idle or revved up a bit. The noisy '97 was a Florida car and is virtually spotless underneath and in the engine compartment. Therefore, I don't suspect a rusting exhaust system, but maybe I should? Stuff looks immaculate underneath. Has anyone experienced anything like this?

[SRK]

Check the engine mounts - it sounds like one has collapsed.

[Ruud]

Not sure if the 1997 engine is similar but in my case the noise came from a cracked EGR pipe. I've had the same on my old 1993 Ls400. More noticeable when cold and heave acceleration. On my '93 the EGR pipe went from the back of the intake (between engine and bulkhead) down to the exhaust. Halfway there is a 'harmonica' bit which easily cracks. I've managed to weld mine and the car was whisper quiet again :)

Quite a fiddly job but certainly not impossible to do yourself.

[Ross W.]

Definitely research the issues already mentioned. My '94 when the EGR pipe failed it was REALLY loud when the valve opened, for instance. But also check for things like an air door in the climate control system hanging open when it shouldn't. They can let a lot of engine noise in if they're stuck open when they shouldn't be.

[jpourcy]

If you are getting vibration along with the engine noise, check the transmission mount. If it is worn flat and the metal on the mount is hitting the crossmember, the engine noise will be amplified through the cabin.

Just get under the car and lift up the transmission right where the driveshaft goes into it. If it goes up and down and makes a thump like metal on metal then the mount is worn. If not, then it is something else.

Jerry

[amcdonal86]

I second the EGR pipe.

[bzublin]

I have the same problem on my 1996 LS400. I got a quote to fix it and the dealer said that the tranny had to be removed in order to get to the broken EGR pipe (labor over $1000). I read some DIY articles saying that the pipe can be removed without having to remove the tranny but I have not tried it yet. I'll tackle it after I fix my power steering leak. The alternator was replaced last weekend.

[RandySC400]

Can anyone give me the link to the DIY EGR pipe replacement my car sounds horrible with the leak...I have a 93 LS400... also does anyone have the part number for that pipe...how much am i looking at to replace it?? Thanks in advance!! RANDY

[lexfourcam]

i agree about the egr pipe but i dont believe the tranny has to removed to get to it. they plugged up my egr pipe when i got s&s headers, and it was right there when i walked underneath the car while it was on the lift. but this was also my 94 you have a 96, it could be different.

[RandySC400]

so are you saying that i can just plug it??what is its function anyway?? I dont have headers but will it effect my car its a 93??

[jtbel]

I believe the egr pipe is part of the emissions system, and does not affect performance if it is blocked off. I just got done replacing the starter on my '97 LS400. I did it myself, and it is not very difficult, but if you are not that familiar with working on cars, it can be really intimidating. I did the procedure twice on mine because I had a sensor that came loose and was making the engine surge. The second time was a breeze. I ordered 2 block off plates from a guy that fabricates them ($8 bucks each). One thing you have to remember is that the plates are 2 different sizes. I found that out after the fact. Anyway, you have to remove the air intake, throttle body, upper and lower chambers, and the rear water bypass which is what the lower egr pipe is connected to. I can give you the guy's email if you want the plates.

[RandySC400]

Jtbel, that would be great if you could give that to me... i replaced my starter awhile ago and was more time consuming than difficult...blocking it off sounds like a great idea...and for $8.00 I can't go wrong thank you!!!

[bzublin]

I completed the EGR pipe "repair" on my 1996 LS400 about one month ago. It was relatively straight forward: remove the passenger side catalytic converter, loosen the bolts holding the lower end of the pipe, and remove the lower portion below the crack. I cut off the excess length of pipe with a hack saw and bent the pipe over on itself to seal it. Then reinstall the pipe. One tip: remove the bolts holding the exhaust pipe to the driver side catalytic converter so that the exhaust system will hang down and provide clearance when removing the passenger side catalytic converter.

I did strip out one of the nuts on the exhaust manifold so I had to drill out the stud and replace it with a bolt. Napa Auto parts had a stud kit so I also replaced some of the studs that looked a bit rusty.

The car is much quieter now. However, the check engine light illuminated a few days after this "repair" so now I need to find out what that's about.

[jtbel]

(The car is much quieter now. However, the check engine light illuminated a few days after this "repair" so now I need to find out what that's about).

This will take care of the cel.

http://www.3si.org/forum/f1/resistor-mod-h...gh-pics-382054/