Hello,

I finally managed to track down a set of the anti-noise / sound encapsulation panels that go underneath the engine and transmission on my 1987 300D. $650 always seemed like way too much money to pay--thank goodness for CraigsList!

I believe that the panels, when new, had some sort of coating on the inside surface, however on the panels I bought it is all corroded away by twenty years of aging and leaking, etc, so I can't really tell what material originally coated these things.

There are images of the new panels, with a foam-like coating at:
http://www.w124performance.com/images/W124_stuff/sound_panels/new_87_front2.jpg
http://www.w124performance.com/images/W124_stuff/sound_panels/new_87_rear.jpg

Has anyone ever attempted to re-coat these sound panels? What material and adhesive did you use? It would have do be something oil / transmission fluid / coolant resistant. Or does it really matter...should I just put them on as bare plastic panels?

Looking forward to a quieter idle!

--Thanks,

--Matt

Fix the leaks first, then consider insulation that you can buy many places such as JC Whitney with the foil surface and open-cell foam beneath.

I believe that the original is an open-cell foam with a facing material, heat-pressed/molded onto the shell. On my '91 I had a leak, didn't know it until that panel was pretty full and started dumping fluid, what a mess. On the other hand, 4matics were famous for leaking anyway, ...

How fortunate for me that an oil-change jockey tossed it for me without my knowledge, by the time I noticed everyone played stupid, no way to recover it.

__________________

Gone to the dark side

- Jeff

I've read that it does make things quieter to have the foam present, but I have the same problem with mine. See www.aircraftspruce.com/menus/ap/soundproof.html for some aircraft-oriented solutions which might work on these panels. I've used some of the closed cell vinyl-nitride foam with pretty good results, but not on these panels, yet.

For the front panel, it appears that one could cut the foam to fit, then brush glue onto the panel, and then vacuum bag the whole thing to produce a form-fitting appearance, as per the photo. I think I'll try that.

The material on the rear panel looks altogether different, and is probably expanding foam, which was put in place with the help of a mold. I'm not sure I want the mold to be the bottom of the car, however!

I've used Dynamat Extreme elsewhere on the car with good results, but don't think it's a good solution for this application.

Maybe someone has actually done this, though. I'd be interested.

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Rob

Thanks for the ideas. Fixing the leaks is certainly a good idea, but given how frequently new ones seem to pop up, it would be nice to use a material that's resistant to chemicals.

I found a product called "VB-TS" by Cascade Audio Engineering that seems like it fits the bill. It is 3/8" foam with an aluminum / mylar surface, and they claim that oil does not penetrate after two months. Not wonderful, but better than anything else I've found.

The spec-sheet on the material is available at:
http://www.partsexpress.com/pdf/268-280.pdf

Also, there are ebay sellers selling it for ~50% of retail. $50 for 14 square feet (VB-TS) / $100 for 28 feet (VB-TSXL).

This does not really match what it looks like the stock material is in the photos I posted links to, but may be a good solution nonetheless.

Matt,

If it has an aluminum surface, it may not absorb sound like the original foam. I think the issue here is sound absorption, vs. vibration deadening. That's why I decided not to use Dynmat on these panels--they're good at deadening body panels, but wouldn't do much about absorbing noise. That's why Mercedes used foam in these panels, I presume. If you get some of this stuff, let us know how it works, please.

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Rob

Why not try to incorporate something like this: http://cgi.ebay.com/ebaymotors/Oil-absorbent-sheets-auto-diesel-marine-fuel-105-EA_W0QQitemZ4618776569QQihZ002QQcategoryZ63703QQrdZ1QQssPageNameZWD1VQQcmdZViewItem as a removable drip control device on the panel(s) or on a skid plate? In addition to the foam.

http://cgi.ebay.com/ebaymotors/Oil-Absorbent-Pads_W0QQitemZ4567350348QQihZ002QQcategoryZ26455QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

The panels on my wife's '87 didn't have anything on them (except a lot of old oil and dirt). I was able to scrape off most of the crud and put the panels back as they were, not knowing anything about an inner liner. I don't think I could get anything to stick to the plastic anyway, given all of the oil that has been on the plastic for years, but just the panels alone help quiet the car. I'm looking forward to installing new padding on the hood, that should help too.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

If it's the case that the panels without foam or any other material do a decent job of sound deadening, I'll just go ahead and put them on as is (once I get my new screws in). Also a good point about adhesive sticking to these things when they're not new anymore.

When I was cleaning the panels this morning, I also thought that if you put any foam or insulation on them, it would will prevent any leaking fluids from reaching the drain holes, which could prevent early detection of leaks.

However, if I do go ahead with any foam (if I get bored and need a project) I'll let you all know how it goes.

Thanks,

Matt

The original foam in the photo does have a facing.
Foil faced is good, but unfortunately it does not contour well and being that it is forming the bottom of the engine bay, the open-cell foam will trap oil, just a matter of time.
I've done a lot of insulating and re-insulating around Cat, Detroit, Perkins, Yanmar, Kubota diesel engines and gensets. It is not difficult to get adhesive to stick, just clean first with a good cleaner like Simple Green Max (autozone).
The facing on the insulation is pretty much a requirement in engine bays, helps to keep the insulation from absorbing oil and fuel and creating a huge fire hazard.
When trying to trap sound, you have several options. Giving the cover some sound-deadening will reduce how much sound is transmitted through the panel by the panel's own vibration. If the material also absorbs sound with an architectural surface (like the hood insulation) then there is less sound to bounce around and escape.
Anywhere air can leak, so can sound.
I've gotten a 10.4liter Cat in the front of one of my Wanderlodges so quiet you could hear the trip odometer click at freeway speeds. It can be done, it's only time and money.
Parallel surfaces are also your enemy, but if one of the two surfaces is sound absorbant, the sound can't bounce back and forth until it finds a way out. Notice the diamond-print on the inside of the hood insulation. It is like many freeway walls where the sound breaks up as it bounces in many different directions, much of it cancels out and it at least isn't directed in any one direction.
Try the panel clean, then add some material to it if you wish, I like quiet also. The CAT in my rigs always had an insulated layer around the oil pan and sides of the block also, makes a big difference.
Much can be learned from www.soundown.com (sorry if this isn't correct, it's close), Soundown is the manufacturer of much of the sound-deadening materials that I use and I believe makes the foam/rubber/foam/foil decoupling insulation that JC Whitney sells, many others sell it but not for that price. It can even be purchased in self-adhesive. They also make high-end stuff like the quilted-lead-fiberglass stuff I've used, but I'm not sure that you can buy direct without either an account or buying large quantities.

__________________

Gone to the dark side

- Jeff

Thanks for all the detailed info on the different materials. I'm basically between trying the Cascade product and the one you suggested from JC Whitney. Looks like the key difference is that the one from JC Whitney has an additional layer of foam, and a layer of vinyl to "decouple" the panel from the foam. The Cascade product is available a bit cheaper, and also comes with an adhesive back, so you don't need to invest in contact adhesive as well.

Do you think it's worth it to spend a little bit more for the additional layer? Does it make a big difference.

I also saw that JC Whitney sells a "Mylar Tape" that might be a good idea to seal the edges of the foam, since I'm planning on duplicating the bare spot under the oil pan as-per the photo of the new front panel. I think this tape could help any dripping fluids flow towards the drain and seal the exposed foam on the edges where I make cuts.

I'll be sure to post photos and impressions when I get the panels / foam installed.

I have to say, it's nice that there are other people out there as excited as I am about sound panels and sound absorbant foam. My girlfriend is starting to think I'm just a bit crazy (but also thinks I got a great deal since I spent $50 instead of $650 on sound panels ).

--Matt

Sealing the edges is a great idea, remember that oil and heat will likely slowly release the adhesive.
I don't think that the decoupling foam is really necessary under the vehicle, and it will make that panel pretty heavy. It certainly would help some, ... if necessary.
The tape I've used for edges is the foil tape that is used on household/commercial ductwork. Even when the adhesive gets weak and starts to creep, the tape stays flat and tends to hold well, also works well around corners like wrapping aluminum-foil around it.
Most of all though, don't overdo it. I'm guessing a 1/4" layer of something that is closed-cell or otherwise won't absorb moisture from the road and from the engine will do 90% as well as something exotic, but with a whole lot less hassle.

__________________

Gone to the dark side

- Jeff

I've just finished gluing some 1/4" closed cell foam onto the forward panel, and found it easy to do, and worth the effort. It has reduced the volume of engine noise both from outside and inside the vehicle. My son offered this opinion without being told that I'd done anything, so I don't think it's just my optimism. I'll try to do the same to the rear panel sometime this week. I purchased this material from Aircraft Spruce and Specialty some years ago, so just used what I already had. I used 3M #80 Rubber & Vinyl spray adhesive.

I'll be interested in hearing about your results.

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Rob

I was thinking of dumping a bag of oil dry on my panels, if I could get it to ride there for a month, and then change it. Leak problem solved!!!

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DS
2010 CL550 - Heaven help me but it's beautiful
87 300D a labor of love
11 GLK 350 So far, so good
08 E350 4matic, Love it.
99 E320 too rusted, sold
87 260E Donated to Newgate School
www.Newgateschool.org - check it out.
12 Ford Escape, sold, forgotten
87 300D, sold, what a mistake
06 Passat 2.0T, PITA, sold

Las Vegas NV