W123 The Quest for Quiet - Page 2 - PeachParts Mercedes-Benz Forum

PackerEdgerton · #16 03-17-2013, 11:43 PM

Ha ha. I didn't think I would get so many "get earplugs" responses!

OK, let me set the requirements differently.

Suppose I said: "I'd really like to be able to carry on a quiet conversation in the 240D while on the freeway."

I'm still thinking:

1) Spray butyl dampener into the door panels.
2) Spray butyl dampener on the underside of the car.
3) Place sound-suppressing foam under seats, floor mats, kick panels, etc.

Then I will re-assess the situation. It seems that would be the highest return, least amount of cash and effort.

What say you?

Thanks,

Packman

Skippy · #17 03-18-2013, 04:59 AM

Quote:

Originally Posted by PackerEdgerton

OK, let me set the requirements differently.

Suppose I said: "I'd really like to be able to carry on a quiet conversation in the 240D while on the freeway."

What say you?

Thanks,

Packman

Sell 240D. Obtain a Lexus or Cadillac, or maybe a W140.

W123's aren't quiet, least of all 240D's. They weren't designed to be. Either you are ok with that or you aren't.

Skid Row Joe · #18 03-18-2013, 06:12 AM

Honda Accord or Toyota Camry might be the way to go for a quieter car.

Stretch · #19 03-18-2013, 07:57 AM

Quote:

Originally Posted by Skid Row Joe

Honda Accord or Toyota Camry might be the way to go for a quieter car.

Oh yeah - but if a die hard diesel fan needs a quieter car then he needs a more modern engine - OM648 yeah baby (not that they can be got in the US that easily so Ive been told)

Stretch · #20 03-18-2013, 08:08 AM

As for practical solutions to noise deadening.

Extreme solution - remove dash and old sound deadening stuff and fit something more modern like this

Introduction

Less extreme =>

Clean / check / protect your door seals - if you have any air leaks on them then you'll get airbourne sound transmission. That could (this is a guess!) reduce the cabin sound by a few dB at 65 mph if they are pretty leaky.

Check your motor mounts etc to make sure the vibration transmitted into the vehicle is reduced to a minimum. Get your engine to run as smoothly as possible - balance your injectors etc...

...check exhaust mounts and replace cracked rubber hoops...

...this kind of stuff might help as well - but we're really scraping the barrel now!

####

Essentially reducing sound at a point of reception is done by either reducing the amount of noise at the source or by making it difficult for the sound to transmit to the receiver.

More modern noise canceling technology is available - BOSE for example make groovy (look like a geek) headphones that help you sleep in business class...

Mölyapina · #21 03-18-2013, 08:31 AM

Quote:

Originally Posted by rscurtis

A switch to a turbo with its 3.07 gearing will be somewhat quieter. An '85 with its 2.88 gears will be quieter yet. I think you'll find that the car is already well insulated. These cars were also products of the 55 MPH era, so they were never geared for 65 and higher.

But it wasn't the "55 MPH" era in Germany, where many large areas of the Autobahn are still without speed limits. This car wasn't meant for 90 MPH, but it wasn't meant to be limited to 55 MPH, either. Sound insulation just wasn't as good 30 years ago, and age has worsened this one.

Quote:

Originally Posted by Diesel911

I suppose a more insulating Hood Pad and some sound deadining Material on the Fire Wall Under the Hood and the same inside would help. I not sure if the same could be done on the in the Transmission tunnel.

I am not sure if there is stuff made specific for that for Cars but they have sort of an Egg Crate type Foam for deadning sound in rooms where People Record stuff.

Here are two threads that I just recently started:

http://www.peachparts.com/shopforum/open-discussion/335938-any-thoughts-insulating-2004-corolla-engine-noise.html
http://www.peachparts.com/shopforum/open-discussion/336023-what-cars-have-good-hood-insulation-pads-noise-reduction.html

Quote:

Originally Posted by marfa300td

Making your Mercedes Diesel Quieter - Dieselbenz.info Wiki

Interesting -- I also remember that there was a long thread by a member who went nuts insulating his 300TD. It had lots of good pictures and information, but I can't find it now.

Quote:

Originally Posted by Stretch

Oh yeah - but if a die hard diesel fan needs a quieter car then he needs a more modern engine - OM648 yeah baby (not that they can be got in the US that easily so Ive been told)

I want that!

charmalu · #22 03-18-2013, 11:10 AM

I agree with what Stretch mentioned above in post#20.

Packer has a 83 240D he wants to make quiter, not buy some other type of car or brand. he has been living with it and may have turned up his radio, probably to hear it above the noise.

These W123 are old cars, and the seals, insulation is old and dried out. I never got the privilage to drive a new one, so don`t know how quiet they were new.

We like these old cars, and like any old car, they need to be gone through to improve and up grade things. It all depend how far we each want to dig into, and how much money we want to add to the project.

I know pulling the Dash and AC/heater control box is extreme, but this is where a lot of the noise is generated from transmitted into the cabin. probably 1 in a 100 on the forum will go to that amount of work.

This article from Popular Hot Rod Magazine (from the link Stretch posted above) shows how to got to the extreme and quite thing down.

Installation Menu

For some reason I can`t copy the PDF file,

but the article in on the top right of the page.

Charlie

winmutt · #23 03-18-2013, 04:04 PM

The tunnel and firewall.... Deaden it.

1983/300CD · #24 03-18-2013, 11:20 PM

Neoprene stops noise pretty well.

The Foam Factory, Acoustic Foam, Sound proofing Foam, Sound Barriers

junqueyardjim · #25 03-19-2013, 12:42 PM

And don't forget to get a correct and good hookup for the exhaust pipe. I just switched out my 716.2 4 speed because one "ear" was broken off. The noise and vibration with a bad exhaust mount was horrific. The transmission itself was a joy to live with, so easy to shift and quiet. But if you can't insulate that exhaust from the car and hold it in the correct place, it is tough to live with. So make sure your insulators on that bracket as used on the steel case or the ears as cast on the aluminum case are in good condition. They are dirt cheap and I suspect they should be changed every 24 months or so.

PackerEdgerton · #26 03-20-2013, 06:54 AM

Quote:

Originally Posted by 1983/300CD

Neoprene stops noise pretty well.

The Foam Factory, Acoustic Foam, Sound proofing Foam, Sound Barriers

Great suggestion! Thanks so much!

Packman

barry12345 · #27 03-20-2013, 08:31 AM

Differant 240s seem to have differant noise generation amounts or levels. in my opinion and experience. Even simple things like the fuel pressure being good make a differance on how the engine sounds on the highway.

It may be a lot of small things that are cumulative in nature. All I am sure of is one of my 240ds is far noisier than the other on the highway. I would almost say you have to get to drive more than one to get some ideal of what I mean.

No matter what you do though I think you will never miss it if the engine is not running. Actually they really scream for a five speed transmission. At this point it is a real shame that mercedes did not put those transmissions in all of them.

MBeige · #28 03-20-2013, 03:54 PM

If the door seals are worn, they will transmit more road noise also.

When I replaced the door seals last year (they were originals), there was a noticeable drop in noise.

W123 sedan door seal replacement (photos)

PackerEdgerton · #29 03-20-2013, 07:54 PM

Well guys, I'm really leaning more towards insulating the 240D with both spray on buytl resonance-blocking material and using the closed-cell foam together. I will try and figure out how much I need to spend, and assuming I do this, I'll document everything in photos and do a DIY and let you know before/after.

I admit, I don't have an audio meter, so it'll be based on subjective measurement by my tired ears.

Thanks,

Packman

PackerEdgerton · #30 04-07-2013, 03:47 PM

Hi guys,

OK, I finally did something about the noise and racket.

I'm trying to reduce the main causes of noise while driving:

1) Road, tire, suspension noise
2) Engine and Exhaust Noise
3) Wind Noise

They are, to me, to be attacked in that order, as that is what I perceive to be the priority order based on what I hear in the cabin at highway speeds.

I am attacking the noise with a 2-pronged approach

a) Reduce resonant noise sources by using what the sound dampener guys call "Constraint Layer Dampening". This means you use some kind of butyl rubber / aluminum sticky material to "convert the vibration to low-level heat". This is a fancy way of saying you stick pre-fab dampening material to change the resonant frequency of the parts that are vibrating, usually to something much lower and harder to hear.

b) Block external noise sources by using closed-cell vinyl and aluminum sandwich.

I'm not done yet, but I started out by researching what the best 'bang for the buck' materials exist. I ended up using two so-far.

i) "Audio Wrap" by Protecto-wrap. Protecto-wrap has been around for 50 years. They make house wrapping and insulation materials. I suspect that many of the big-name audio sound suppression guys are simply OEMing their materials from places like Protecto-wrap. I purchased a 60SF roll (it's about 15" x 50'). It was a couple of hundred bucks, shipping included. MUCH less expensive than anything else I could find on the market, and is made by a US company who has been around for decades.

ii) I used Frost King vent insulation from Home Depot / Lowe's. It's about $18/roll, and is designed to be used in houses, on ventilation HVAC to both insulate sound, vibrations, and heat, etc. I figured it is supposed to block sound and vibration in a home setting, so I'm comfortable using it in the car. It's NOT an 'exterior' product, and is designed to used around living spaces inside homes, so I believe it's not toxic, etc. I purchased 3 rolls.