Sound deadening ideas needed!

[DeliveryValve]

Hello all,

I have quite a few people telling me that my interior cabin is a little loud on my 300d. It never bothered me because I always thought that's the way it was supposed to sound. Even with the other 300d before it's been a permenent fixture in my driveway sounded the same.

Anyways, have any ideas to lower noise coming in? It seems like a lot of the noise is coming from the passenger side dashboard.

Any help would be appreciated.

Richard

[Mismost]

Well, I laid foam rubber padding about an inch thick behind the kick panels under the dash and under all my carpet pads...cuts down on noise level and cushy to boot.

I know this isn't some hi-tech, high dollar solution....it was use the foam or trash it. Glad I used it, it does help.

[probear]

Check here http://www.b-quiet.com/
I used their material on my 99 F-350 and it made a difference.

[300SDog]

I would probly try spray foam insulation in aerosol cans from Lowes and/or instead of sheets of foam padding. Thinking I'd hose a few inches of the stuff up against the firewall filling nooks and crannies inside. Also outside, like underneath the battery tray and along the existing firewall padding. But most common noise problem on old cars is probly weather stripping around the doors.

[sixto]

Be careful with additional padding if your car leaks. Mold and mildew are health hazards.

Sixto
93 300SD

[Shorebilly]

Originally Posted by probear

Check here http://www.b-quiet.com/
I used their material on my 99 F-350 and it made a difference.

Thanx for the link, looks interesting, bookmarked link for later in my project...

SB

[Ramblin]

Although this thread is actually about the stereo in the car the sideline about the sound deadening is what is what this discussion is about. This installation took about 4 hours (dynamat) and dramatically reduced the amount of road noise and other noises. The Dynamat cost about $300
123 Install Extreme Dynamat

[barry123400]

Want to kill the noise and it's not even a 240d? It just occured to me that there are electronic noise eliminators. I assume they pick up the noise and feedback it in reverse phase cancelling it out. Should have been optional or standard equipment on 240ds, I might try to scan ebay for a surplus setup. This being said if I want one in the future I will probably pay dearly from now on. Perhaps I should go have a look so we can bid against each other. Electronic noise canceller or eliminator? Perhaps there is a home for the surplus ones now. Maybe a plan as one of my 240ds could really benifit. Will go have a look for them. A 240d dead quiet at 80 mph? Nobodys going to believe it. With my luck they were only produced for headphone use. Applications like elimination of the noise of the jackhammer for the operator perhaps. That should be almost enough for 240ds at high speed. Really though the most practical approach probably was the shell someone produced at some time to drop over the engine. If one ever turns up on ebay the bidding just might be spirited. Especially if someone reports it's listing on our site. Perhaps a current copy of that item might sell well again if someone could get hold of a sample to examine and perhaps make copies of. I know I would like to try one if pratically designed and not too expensive. There are two questions I never hear in my 240ds come to think about it. One is the engine running? The other being is this really a diesel? I remember someone suggested doubling up the hood pad somewhere. My though is to build a special cover for the valve cover might produce a difference to some extent and that project should be managable. There is a lot of noise radiating from that source I suspect. . Just putting a couple of fibreglass batts on it and driving around the block might prove it. Or more likely just positioning them temporarily on an ideling engine may be all the proof required. No sense doing anything though unless your motor and transmission mounts are in pretty good condition I think. The first avenue of atttack is to get the sound level back to about the new car condition before moving on. As my youngest daughter quoted when I drove our first diesel into the driveway many many years ago. Why are you driving a tractor now dad? One problem I might experience is with my family dogs. They know I am on my way home in advance to some extent. My wife claims they indicate they hear the car. Have a bite to eat and perhaps a short nap. Then I arrive in the driveway. Must be somewhat frustrating for them if it"s someone elses diesel going past. Then there is the practical approach, Buy up a clapped out 240d automatic. Drive it at speed for a week or two. When you slide back into your 300d the noise will be gone. Every time the noise reoccurs just drive the 240 for a few days. I guess we could perhaps borrow a decibel meter and get comparisons at various speeds just to verify what we think is normal first. My experience so far is a wide lattitude of noise from identical examples . Yet they were all pretty close to each other when new. Do not blame me too much for this missle. You did ask for ideals and abstract ideals have a place as well.

[Whiskeydan]

Someone suggested a product from Lowe's called 'peel-n-seal' as a cheap substitute for Dynamat.
I believe its a gutter sealer found in the roofing dept. $10 for a big roll is worth a try.

[OMEGAMAN]

I used Jute in the under the dash of my car and it worked great. Jute is the stuff used originally in the car but I think it becomes compressed over the years and ineffective. You can get it at an upholstery shop cheap

[barry123400]

Whiskey Dan, that sounds like a great ideal. Since it incorporates an intense bonding agent it would help kill off any resonance present and radiating off the metal as well. It is also totally waterproof too. So it will not become damp and hold moisture. If the product is what we call ice edge for roofing the product is pretty good for this application in my opinion. In fact about the best I can think of now you have brought it to my attention. Any good roofer might sell you a small amount as a roll of the product is more than you need I suspect. The adhesive is so good just make sure you put it where you want it the first time. If your surface is clean and dry I suspect you will be unable to reposition it. It helps kill any resonance at point of origin rather than trying to mask it after generation/radiation. Lay in unbonded materials do require a lot more bulk to dampen out the noise after generation. You have actually changed the mass of the floor material to dampen resonace at source in my opinion. A better approach. And the back of the economic equation has been broken with this material as well. I would like to see a forum menber try some and let us know. Or perhaps someone else already has and could post the results. Just would prove it is a good economical sound approach. (pun unintended) It also could be thickened or laminated up as its real strength is bonding to itself. You cannot get it apart once contact is made.It is about an eighth inch thick if I remember but my memory might be faulty. Anyways it will not give problems associated with too much mass. Some members have already used the product for their roofs perhaps and could add to this. It is fundementally going to act the same as greatly thickening a layer of undercoat. That I believe was the primary sound insolation anyways on these cars although sprayed underneath the floor.

[Carrameow]

Go to a Junkyard--and get the stuff from the Inside of Late Model Volvo doors..that stuff is expensive but you can get it from them for pennies or free....BTW, a well tuned 85 300D is not that loud, its actually pretty quiet. Your problem may be elsewheres--

[DeliveryValve]

Great suggestions everyone!

Originally Posted by barry123400

No sense doing anything though unless your motor and transmission mounts are in pretty good condition I think. The first avenue of atttack is to get the sound level back to about the new car condition before moving on.

Originally Posted by Carrameow

BTW, a well tuned 85 300D is not that loud, its actually pretty quiet. Your problem may be elsewheres--

I have new motor mounts.. Transmission mounts I’ll have to check… But the engine seems to running great AFAIK.

Originally Posted by barry123400

Then there is the practical approach, Buy up a clapped out 240d automatic. Drive it at speed for a week or two. When you slide back into your 300d the noise will be gone. Every time the noise reoccurs just drive the 240 for a few days.

I would do this.. In fact the noise doesn’t bother me. It’s really for my passengers.

[ConnClark]

One of the best things to absorb sound is potatoes. Coat your Benz inside and out with potato wedges. You'll have to replace them once a week to keep them from rotting.

Its just an idea, not a practical one though it will work.

[vstech]

Originally Posted by ConnClark

One of the best things to absorb sound is potatoes. Coat your Benz inside and out with potato wedges. You'll have to replace them once a week to keep them from rotting.

Its just an idea, not a practical one though it will work.

he he.