Soundproofing my 84 300td

[b2948kevin]

So, for some reason, I thought it would be a good idea to try to soundproof my diesel Benz this past week. At first, I thought that I would start fixing some things that were starting to bother me. I started at a junk yard by picking up some parts to fix that air leak in my fuel system. I then found some very nice interior pieces and dome lights. It was a real nice Saturday.

It's now midnight 2 weeks later after my small quest to fixing things has surmounted into a very large project including a new stereo (my old one was broke), new speakers (might as well), and a project that I've had interesting in for a while, soundproofing my entire car. Don't ask me how the train of thought went. I'm still trying to remember it. I want to caveat here that I am not trying to break any sound system records or destroy the neighbor's windows. I actually don't listen to very loud music, in fact I am usually caught listening to political talk radio. The reason that I am doing this is to try to eliminate as much road and engine noise as possible for a more comfortable ride.

After hours and hours of research, I decided that the best way to soundproof my car would be to use the 3 layer approach as described at sounddeadenershowdown dot com. The first step includes laying Dynamat as a sound-deadener, adding a layer of closed cell foam to block some noise, but mostly to decouple vibration from the third layer which is mass loaded vinyl and used to block noise. Yeah, it's gonna be a pain. I haven't even gotten to this part, and I'm already not looking forward to it. So, there you have the 3 layered approach. I will deaden resonating panels and block noise using MLV. The foam is in there somewhere too.

In my now obsessive quest to soundproof my car (as close as possible, at least), I've spent hours tearing out the entire interior, during which I decided that I'd need to get new carpet. I've also started a very long list of materials and projects that I will need to complete or buy. Am I insane?

Here's the plan:

I bought 100 sq foot of Fatmat vibration dampener, 200 sq foot of mass loaded vinyl (bought 150, they gave me 200, I later realized) and I am ordering 8 yards of Raamaudio's Ensolite foam. I have the interior taken out (see photos) and am working currently on taking the stock vibration dampener mat out. After this is out, I will cover most of the bare metal, but I won't be excessive. One layer should be enough to dampen the panels. I will then lay down the Ensolite layer with contact cement to cover everything. The next layer will be the mass loaded vinyl. This will be laid using contact cement again over the Ensolite. In problem areas, I will double up on the MLV.

I've searched fairly exhaustively on this forum for a documented project similar to mine, and I've yet to find one. For this reason, I've decided to use this to document my project so that it will hopefully be useful for someone else down the road.

Tips:

There are at least 5 different stock sound deadening materials in the 300td. Some of them seem to be pretty decent. Some come off easily with a little heat, and others refuse to come off without scraping every inch with a screw driver. Underneath the driver and passenger mats has been the worst, second will have to be under the console. Everything else has been pretty easy.

[b2948kevin]

So, I made some progress on the FatMat installation tonight. I finally got the last of the stock soundproofing materials off and have begun to lay down the good stuff. Good news is that this California car has no issues with rust. There was just a bit of surface rust, but I brushed it away. No issues here.

I zip tied the wires and vacuum lines over the console to give better access so that I could formulate a gameplan around how to approach it. There's a thick sound barrier behind the firewall already that I've decided to just leave in place. I've torn enough stuff out, and I am going to decline to take the dashboard apart. I've already bitten off a lot, and I don't want to continue taking stuff apart (Mercy!). I've decided that I will just attach MLV on top of the factory barrier in the places under there that I can reach.

I ordered Ensolite from Raamaudio today. Those guys provide stellar customer service. I'll give another review when I install and test their products, but all other reviews are extremely positive. They had decent prices too.

One tip that I want to share is not to order FatMat. I learned too late that Fatmat is not a Butyl mat, it's a rubberized asphalt mat. While Asphalt still works, you may as well go with the best stuff out there, which is the butyl with non-asphalt fillers. All of this information can be further researched at sounddeadenershowdown dot com, and ironically, Raamaudio comes out as the clear winner in the mat category.

[Dee8go]

Thanks for posting this. I have had in mind to do the same thing to my SEC. I need to find a full compliment of the snap in plastic fasteners that hold all the interior panels, carpet, etc. in the car. Half of mine have broken or been lost and I currently have parts akimbo.

[Dee8go]

BTW, nothing says "quality" about a car more than that resounding thunk when you shut the door and the quiet you experience while driving.

[b2948kevin]

Agreed! It's good to hear that this will be useful in the future. I'll keep up on the updates as things progress.

[b2948kevin]

Also, I have no clue where to get the plastic fasteners. I broke a lot of them during the dis-assembly, and really have no gameplan on how I will be replacing/working around this issue. Any suggestions?

[Dee8go]

That's why I mentioned it. I guess you could get the part numbers out of a repair manual, but I don't have the one for 126s. Once you have the part numbers, it should not be too hard to buy the fasteners. You can probably get them from Phil.

[b2948kevin]

I got some more work done on the wagon today, although I am a little short on pictures tonight. The battery wasn't charged, so you only get one.

I got the remainder of the Fatmat installed in the passenger foot area. Overall, I have Fatmat installed in the front foot areas, under the front seats, and under the back seats. I still have to put Fatmat in the rear area, but I'm leaving that until I get the seats back in the front. I'm trying to focus on getting it drivable again, and then I'll finish up the rear area.

I ordered some carpet from a local upholstery shop today. It should be in tomorrow. I found out that the OEM carpet is over $150 per yard and a carpet kit for the wagon runs in the $960 range. It was an easy decision to go with some aftermarket carpet in the $15 per yard range. I found something similar to the palamino, but it's just a little lighter and a little more brown. I don't think it will look bad.

As you can see in the picture, I put the radio in today. I also replaced the rear speakers. I had planned to use this pair of speakers (I only have one pair so far) in the front, but the little tweeter in the 2-ways stuck up too far and would hit the cover when I put it back on. I was pretty disappointed, but I got over it and just installed them in the back. Does anyone have a recommendation on a good-fitting OEM replacement speaker?

Another item that I accomplished today was that I laid mass loaded vinyl underneath the center console. I didn't want to wait for the foam to come in to get the console and radio installed, so I opted to just put the mass loaded vinyl in there without foam so that I could meet my milestone goals. I used 3M Super 90 spray adhesive which seemed to work really well. One thing I learned is that when the directions say to spray and let sit for 1-3 minutes, it really means you should do that. I thought I was too cool for school and started putting it on right away only to find that it just doesn't stick for a while. Save yourself the personal lesson and take it from me. Just let it set for a while and you'll be fine.

After I got the MLV laid, I put the center console in and began routing all the wires to their locations. I spent a lot of time making sure that all the wires and tubes laid in their proper tracks and that they were all accounted for. I feel that I did a good job, but I feel that I spent a lot of time on this seemingly simple task.

Amid all of the other things that I did, I spent some time working on the rubber trim and chrome on the car. I have all the rubber trim and rubber bumpers off which was the perfect opportunity to scrub them up and wash them with the hose. I then scrubbed the locations where the rubber touched the car. There was a lit of dirt that had accumulated under there which I was unable to get to. After wiping it down, it looks nice again. I'm anxious to get the rubber back on and see what a difference it makes. As for the Chrome, I spent some time with a fine steel wool on the bumpers and around the grill area. I was stunned at the difference that it made. It took that old dingy, exhaust faded rear bumper and made it look new again.

[b2948kevin]

I finally feel like I am making some progress on project now. I received the Ensolite foam today and made a goal to get a good bit of it in tonight. I also ordered some recommended spray adhesive from Raamaudio which really turned out to be some great stuff, at least in the application. It didn't require as long of a sit time before you could get a good tack. The Ensolite was ordered on Monday and I got it today which is really good shipping time for a standard UPS ground shipment. The foam seems to be good quality and was much easier to put in than I had imagined. It stretches a good deal when you need it to.

If you look at previous pictures, you will notice that the air ducts on the front floorboards create a pretty awkward surface for mounting anything to. I then decided to look closer at the factory floor mats that I took out and realized that there's a foam pad that's cemented onto the carpet. I pulled the foam pad off of the factory carpets (there's pads on all 4 facroty carpet pieces for floorboards), cemented it down, and laid the Ensolite closed cell foam (CCF) over the top. I think it looks pretty good for a night's work.

I didn't have time to go get the carpet that I ordered. I will hopefully stop by and pick it up tomorrow. I'm not in a huge hurry because it will be a while until I need it.

I also spent some time getting the front speaker wires in location and getting the radio wires put back into the recess. Things are finally coming along .

[b2948kevin]

Also, as a quick update, I used a full 4 yards of Ensolite foam on the progress seen above. I would estimate that a sedan would require about 5-6 yards for single layer coverage, not including any door panels. I bought 8 yards and I think it's going to be just about right for my wagon, but not much extra. When I do the doors, I think I will be ordering some more.

For the FatMat, I've used about 40-45 square feet so far for single layer coverage for the progress that I've made so far which includes everything from the front foot panels to underneath the rear seats. I still have a decent amount to do. This said, I have about 60 square feet left and I'll probably have a little extra for the doors. We'll see.

[b2948kevin]

Although I didn't plan on doing much on the rear area yet, I decided to build some of it out. I went to pick up the carpet yesterday (2 days after I ordered it, when they said they would have it next day) and it wasn't in. They said that they don't expect it until next week sometime . Don't do business with Quality Upholstery in Reno, NV. With this information, I decided that I would have plenty of time to work on getting everything up to snuff in preparation for the carpet.

So far, I've used about 60 square feet of Fatmat be lining the entire floor area throughout (see pics) with a single layer. I should have enough to do the hood and some of the doors.

[b2948kevin]

After I got the FatMat laid in the rear, I went forward with the foam. I was pretty impressed with the visual (and mental) improvement that it made to the project, and it makes me feel like I'm really making some progress. I did some measurements and decided that I needed to leave the foam off of the spaces where the rear floor panel will re-attach. I will need to lay carpet in that space later and I don't want it to be too thick after the fact.

So, I finally now have a single layer of foam throughout the majority of the car. I'm now fully ready to lay the MLV which is much more stiff and will most likely be a real pain. I am thinking that I'll cut strips of about 6-10 inches wide and just using them to tile the floor in an overlapping fashion. I'll experiment with a few different methods to see which is the best.

Below is a cost breakdown so far. Starting to wonder if it's going to be worth it.

100 Sq Ft Fatmat, Ebay: $170
Radio and 2 Speakers, Crutchfield: $305
200 sq ft Mass Loaded Vinyl, SuperSoundproofing.com: $170
72 sq ft (8 yards) Ensolite Foam, Raamaudio: $100
6 Cans Adhesive, Raamaudio: $30
5 Yards Carpet, Quality Upholstery: $80

Total: $855

[Dee8go]

looks like it's coming right along. Did you run all of your wiring underneath the fat mat?

[b2948kevin]

Good question. I ran all of the wires and vacuum lines over the top of the Fatmat, but underneath the Ensolite foam. I tried not to spray any of the wires with spray adhesive, in case I ever need to get to them in the future.

[PanzerSD]

Looks awesome Kevin! It's going to feel like a sensory deprivation chamber.
I did VERY little sound deadening on one other car I used to own, and it made an insane difference just adding a dampening panel to the inside of each door, I can imagine what you did would sound like. I may used this posting as my guid line when I do my SEL. but I'll be doing roof as well.