LS400 too much road noise?!

[ls400storm]

Dear friends

To give you a quick background, I have owned sever cars in the past like a Mercedes W140 S600, Toyota Cressida, 1992 LS400, Lexus IS etc. I am capable of doing general small repairs etc on my own and am generally technically minded.

I just purchased a 1998 LS400 last month with 97,000 miles on the clock. 

Here are my problems, hope someone can be kind enough to help diagnose my issues-

1.     1.  I hear a lot of road noise in the car from the front right of the car. The noise is similar to tyre noise when driving any car on a worn old road. I had to change the front two tyres anyway after I purchased the car since they were old. The new tyres have made no difference. My friend a mechanic has checked out the front bearings and he says that they are fine with minimal play. The road noise starts from 10mph onwards all the way to highway speeds and increases with speed. Me shifting the car left or right at speed makes no difference to the increase/decrease in sound. Brakes are good and not sticking or anything like that. My 1991 LS400 had no road noise and was much quieter in this regard. One more thing, the noise increases and becomes much apparent on new/smooth roads. The mechanic friend cannot hear anything unusual but I am sure something is not right given my experience with these cars.

2.     2.  After driving the car for 10-15 minutes from cold, I get a creaking sound from the rear left suspension. I greased the sway bar bushings but this noise still occurs. The noise disappears after after the car has not been driven for day/two and reoccurs 10-15 minutes after the car has been driven. Do the LS400s suffer from bad struts? Given the car has only done 97,000 miles surely the strut should be ok? Or does anyone have any other hints?

Hope someone can help so that I can get the car in order.

Thanks

[royoftherovers]

Hi Mark,

Sorry to learn of your problems.

Some suggestions for your consideration.........

1.Check door and window seals on all doors.

2. What make of tyres do you now have on front?

3. and on rear?

4. consider changing tyres..back to front and front to back

 

Regards

 

John

[Malc]

............  I sometimes used to get ( wind )  noise from the front nearside ...  I guess it was wind noise, it vanished when they fitted a replacement windscreen.

Malc

[ls400storm]

Hi John

1. I will check the rubbers, thanks. This is interesting.

2, 3. Front - Bridgestone Turanza GR90 ... Brand new.  Rated as very quiet tyres for luxury cars.

Rears - One is a Dunlop and the other is a Hankook - again both almost new with less than 1000 miles.

4. Thing is that noise has not changed even a bit since I got the fronts replaced so I suspect that the tyres are not the issue. I will do this anyway at some point. 

Malc - I hope the windshield is not the issue!

 

Any more suggestions are most welcome.

 

Thanks

 

 

 

[runsgrateasanut]

What pressure are you putting in your tyres?

I sometimes get creaking going over speed humps slowly, and then they seem to disappear for some reason. I'd say they are front creaks rather than back. 

 

[ls400storm]

Hello

I am running 30psi all around.

Also, the creak is from the back, when I bounce the car up and down it creaks.

 

Thank you

[bigjap]

don't know the noise,sometimes the wrong sort of wheel balance weights can be fitted in the wrong place and will rub on brake calipers ,there is very little clearance there

[runsgrateasanut]

Thinking back  I had a broken spring on my W140 once.  I think it was the rear?   Just broke at the base. Could be the cause of your "creaking".  I have two replacements rear springs which I've done nothing with but carry one on long journeys "just in case" as they are an "advisory"  for rust.

 

[PJD]

Grease all the seals up with silicon?

 

 

[ls400storm]

As per Malcoms suggestion re the windscreen, I tried to investigate. I have found that I the car had a replacement "safevue" windscreen at some point. The bottom of the windscreen at the corners has a milky like appearance that means that the windshield is delaminating and there is water ingress due to a faulty seal or incorrect installation. Clearly the replacement was not installed correctly or has gone past its age. The area near the drivers side A pillar windscreen looks the worst.

To check that, I took a friend along for a ride on the motorway. I asked him to identify any issues with the windshield with the car running at speed and when he ran his hand he said that he could feel the outside (10 degree) cold air where the dashboard meets the windscreen near the driver side A pillar and 3-4 inches towards the left of the A pillar just before the windscreen defogger vent starts. I ran my hand at the spot too and could feel the air leak. You can clearly feel some outside cold air from 35-40mph onwards. The passenger side is just fine, with no leaks.

I therefore have a strong suspicion that the windshield may not have been installed properly which is causing me to hear outside noise. I am going to attempt to repair this at the cheap using some RTV silicone. This will mean removal of the black plastic protection that runs along the width of the car and meets the bottom of the windshield. Once I manage to remove that, I will clean up the windshield as best as I can at the bottom using carb cleaner. I intend to run a thick bead of silicone where the bottom of the windshield meets the body and smooth it out. A bead of silicone also needs to be run along the windscreen A pillar joint.

If anyone has any tips, feel free to add. I will try and attempt this shortly and report back with pictures.

 

Stuart, the springs look mint/probably new without any corrosion, But I will get my friend the mechanic to check this over when time permits.

 

Phil and John - what would be cheap and good for seal rejuvenation? would something like GT85/wd40/brake fluid/armor all work?

 

[Tulpen]

During the time I had my 400, I had to have the windscreen changed twice and watched them do it both times. This is not an easy process (forget the old days with bent wire coat-hangers), it involved special sealant and precise curing times. Removing the trim and sealant was a delicate operation. You might consider taking it to somebody like 'CarGlass' and getting them to reseat it for you.

[Malc]

.............. I too would seriously consider getting your screen professionally re-seated, it might be quite simple to a professional.

Malc

[runsgrateasanut]

21 hours ago, ls400storm said:

Stuart, the springs look mint/probably new without any corrosion, But I will get my friend the mechanic to check this over when time permits.

Just a thought and I'm no expert but wondering if the springs have been replaced if the bushes on the Control Arms and Struts needed some sort of silicone on them if they were cleaned up before being put back. No doubt others will correct me on this.

[ls400storm]

Thanks all for your help.

1. Windscreen is being replaced by the insurers in the next few days. I had a long discussion with them today.

2. I have reconditioned the seals using Gummi Pflege. Definitely has cut down on the wind and outside noise.

3. Had no time to check the suspension, will check this and report back at some point. 

 

thanks