2nd Gen Non-Engine/Transmission Noise reduction effort update

[TomGolden]

I agree with KL in that now I really notice the noise coming from the engine compartment through the firewall much more since I added the SoundStop foam to the floor and rear cab wall.



Those 2002 trucks must have something my 2001. 5 doesn't, as my truck has the carpet and a 3/8" or so thick layer of house carpet padding like material, no asphault like material for sound supression.....



Oh well... I just ordered 2 more sheets of the 1/2" SoundStop foam to do my main doors with. I would also love to be able to do something on the firewall area, but just don't see how that would be possible.



Tom

 

[cmckinney]

The only difference between the 02' and 01' trucks as far as sound proofing is that you have a hood liner and we don't. I haven't noticed anything else we have the same standard rubberized insulation in the cab by the firewall and the woven fabric covering the firewall on the engine side.



I thought LSFarm had done his firewall. If he did I wonder what he did.



-CM

 

[Lsfarm]

Firewall work

Hi CM, well how do I describe it, if you look at my firewall from the engine side you can't see any painted surfaces, it is all foam covered. And behind most of the factory sound blanket I slid a layer of Soundstop foam as well. I took a lot of time to cover as much as I could, and resorted to using some rather small pieces of foam and cutting slots to go over wires and cables and hose for bolts etc. I glued these pieces to the firewall.



There are no bare metal surfaces that the cummins clatter can hit and radiate the noise to the inside of the cab.



I also covered all the bare metal on the inside of the firewall around the steering column and pedals and behind the heater outlets on the top of the hump.



I put foam behind the little kick panels in front of the doors, and pushed foam up between the heat/AC unit and the firewall in front of the passenger side.



Every little bit helps, and as said in an earlier post, once one area is quieted down, the another seems noisy, but it was alway noisy, just was masked by the other loud areas.



Just keep 'whittling' away at it, and soon it will be pretty quiet. My truck is still noisy when stone cold, but is is a lot better than when uninsulated.



Do a search on 'Noise Reduction'. There was a rather lengthy thread last year around May or June that has lots of photos and ideas. I can't find the link to it right now.





Greg L The noise Nazi

 

[cmckinney]

LOL



LSFarm - You are a dedicated noise reductionist.



Well I guess I'll start with my cab and start putting sound deadening insulation in my floor board and else where. I may just start putting regular foam boards on the panels and see if they quiet down the cab.



-CM

 

[Dave Zuber]

I did some testing on my 2001 with the decibel meter and found more sound coming from the floor area (straight down) than from under the dashboard (straight ahead). There was more coming from the passenger side than the drivers.



In a previous TDR mag there was a story about a thermal sound blanket install on the engine from B-Quiet. These guys:



http://www.atpwrap.com/dodge_ram.htm



His testing showed lots of interior noise coming from the exhaust down-pipe. My testing supports this.



He showed that most of the exterior noise came from the oil pan.



Question: If you wanted to, how to deaden the firewall? There is too much stuff in the way. Is there a spray on like the old undercoating?

 

[Gary - K7GLD]

Think INSIDE the box!

At some point in aggressive noise reduction, you're bound to be confronted with APPEARANCE of the mods you hafta make to reduce noise levels - if noise reduction is a serious issue with you - and looks secondary, why not enclose the Cummins in a sound proof box?



Seriously, many modern hotrods are doing that, and when you lift the hood, you can't even SEE the engine! THEY do it for cosmetic reasons - but the same approach could work for soundproofing as well - and need not be ugly if done properly!



Some trial fitting with cardboard around the engine and accessories, attempting as much enclosure as possible - without unduly sacrificing serviceability of the engine - SHOULD work better than simply plastering soundproofing material on as many existing surfaces as possible... Once a basic usable structure is arrived at that meets required servicing needs, sheet aluminum and selected soundproofing materials could be used to fabricate a final "sound-proofing" enclosure.



That should work well with sound radiated outward and upward, leaving only that which is directed downward to deal with... Some might be concerned about air circulation around the engine - but I really think the problem would be getting ENOUGH coverage - not TOO much!

 

[Pit Bull]

Originally posted by cmckinney

The only difference between the 02' and 01' trucks as far as sound proofing is that you have a hood liner and we don't. I haven't noticed anything else we have the same standard rubberized insulation in the cab by the firewall and the woven fabric covering the firewall on the engine side.



I thought LSFarm had done his firewall. If he did I wonder what he did.



-CM

My 2002 3500 Regular cab that was made in Mexico city came with thick rubberized undercoating under the cab. I did not have this on my 2000 3500 Quad cab that was made in St. Louis. I am sure it helps the road noise but I can't tell because the engine sounds so great

 

[Lsfarm]

Think and research AWAY from the keyboard

Gary: Try doing a little research and thinking before getting on the keyboard:



Quote: "SHOULD work better than simply plastering soundproofing material on as many existing surfaces as possible... "



If you had thought about it and remembered what it was like to hook up your comp box, then you would realize that there is no practical way to make an aluminum box to enclose the engine and transmission. The transmission would have to be included because it is bolted to the noisy engine and conducts and radiates engine noise.



The engine has a cherry red [when under power] turbo and exhaust manifold, an exhaust pipe and over a dozen wires, cables, and linkages attached to it from an equal number of directions. This makes it impractical to try to enclose the engine in single box of any material that insulating materials could be attached to.



In fact the engine is ALREADY enclosed in a box: the engine compartment. This is what has been insulated on the inside by attaching appropriate noise reducing products to virtually every available surface.



If you had done some research you would have found the image that I've attached below in a previous 'Noise Reduction' thread. This image shows that to the greatest extent possible and practical the engine has been enclosed in yet another box of insulation. If you research further you will find that the oil pan is also enclosed in lead and foam.



So I'm not recommending to 'simply plaster soundproofing materials on as many exsisting surfaces as possible' without a lot of experience in reducing the noise from our engines.



The factory provided engine enclosure [the engine compartment] provides easy access [the hood opens] to all service items. Adequate clearance from hot exhaust manifolds and exhaust pipes. The only thing missing is the noise insulating products on the inside of the compartment.



Therefore: insulate the engine compartment !





Greg L. The Noise Nazi

 

[Pit Bull]

Greg, have you ever checked out a Lexus LS 430. You can't hear the engine running, even when you are standing outside beside the front fender. They are the quietest vehicle I have ever seen. You should check one out. See what materials they might be using. Just a thought. Hope this helps you on your quest.

 

[Lsfarm]

Noise Sources

Dave: I found the same Db readings when I tested a couple of other trucks.



There are several sources of noise that assault us in our trucks [largest source to least source]:



The Cummins Engine

Exhaust PIPE Noise

Road Noise

Exhaust Noise



The real problem with our trucks is that the passenger compartment is really just a tin can, and Dodge did very little to try to block or absorb the outside noise.



Obviously the Cummins engine creates a lot of clatter, but most of the drone or 'sound of power' that we hear when climbing a hill or towing is the result of the exhaust PIPE itself.



I'm experimenting with making a double wall 4" exhaust pipe to help eliminate some of this pipe noise. I'm going to split a length of 4" pipe and expand it enough to slip it over the inner pipe and mig weld it to the inner at the split . This should do two things: add mass to the pipe to change it's ressonace frequency, and add a layer or boundary to reduce noise radiating from the pipe.



ATP Wrap has a down pipe blanket available, but I had GSI make one for me. www.soundstop.com



The exhaust pipe noise and road noise comes through the tin-can back wall of the cab with virtually nothing to block it but the rear seatback. This is why just adding anything to the rear wall behind the seat helps so much.



I still plan on adding another layer of lead sheet to the passenger side floor. I just have to find time to pull the seats again.



But with all the good reports from the insulating of the door panels, I will probably do that next.



Thanks for all the feedback guys, with every 'noise reduction' thread, my truck gets quieter and quieter!



Greg L the Noise Nazi

 

[Lsfarm]

Silent engines

Thanks Pit Bull, while I haven't looked at that particular car, I have opened the hood on a lot of very quiet cars to do a little 'research'.



What I've found is that there is rarely any really 'special' insulation in the engine compartment, but more an attempt to just not leave any area uninsulated.



But the really quiet Mercedes diesels are the ones that intrigue me. I used to work for DaimlerChrylser before the 'Diamler Debacle' ended my career with them. I had the opportunity to speak with a couple of their engineers and ask how they made their diesel engines so quiet.



This is what I was told, I haven't been able to verify it all, but it makes sense:



Double wall valve covers, double wall exhaust manifold shields, and double wall exhaust pipes are used to a great extent. The injectors, injector lines, and injection pump is either burried or shielded wherever possible.



I've looked into trying to make a double layer oilpan, but even if I could make or buy one, it is a small war to change an oil pan on our engines.



Even though I'm 'the Noise Nazi' I still can't justify a whole day's work for a few Db's reduction. Instead I covered my oil pan with a layer of lead sheet and a layer of GSI 1/2" soundstop foam. This dropped the Db readings by 8-10 Db coming from the underside of the engine. This is a very noticable amount.



I'm going to try the double wall exhaust pipe, [see above post] and have an effective sound blanket over most of the injection lines, valve cover and intake. I need to try one of the exhaust manifold blankets and do a before and after Db reading. They are pretty pricey, and I don't want to spend the cash unless I will notice a Db reduction.



My engine reads about 6-8 Db lower than a stock one with the Db meter held 18" or so above the Valve cover or the intake side. No difference over the exhaust manifold side.



Thanks again guys, I'm headed out to the shop, [I'm home for a change] maybe I'll make it quieter yet in a few hours.



Greg L. The Noise Nazi

 

[cmckinney]

LSFarm-



So you covered your valve cover and intake horn with foam? (Referring to your picture in previous post)



-CM

 

[Gary - K7GLD]

"Gary: Try doing a little research and thinking before getting on the keyboard:



WELL, jeeze Greg - sorry to have so deeply upset you...





SO, yer saying before YOU ever contribute to a thread, you carefully do a search on ALL related threads and posts on the subject, carefully read them all - THEN add yours?



UNH-HUHHHhhhh. SURE you do... .



Fact is, if'n YOU had read both my posts on the issue, you mighta noticed my statements that the "noise issue" doesn't really rate all that high on my list of priorities - thus, doesn't really rate a great deal of research and digging - what I WAS doing, was simply offering another casual suggestion that I figured might not have been tried - and for the record, *I* don't really consider the Dodge underhood area to be all that more cluttered or difficult to work in than other types for the purpose I suggested...



BUT again when logic and reason turn into insult and personal abuse, time to leave the thread...



(it really WASN'T necessary, was it?)

 

[Lsfarm]

Actually yes I do

Gary, yes I do research, before I belly up to the keyboard. I don't offer opinions on threads that I have little if anything to offer but an opinion.



I wouldn't go to a thread about towing with six-speeds in the Sierras, Rockies or Cascades because I haven't done that, my offerings would only be opinions, and a lot of Yada, Yada, Yada.



Your 'casual' post about enclosing the engine would have been welcome to me if it didn't have that slightly insulting barb thrown in.



The hotrod guys create their own linkage, exhaust, wiring harness and have a huge choice in intake systems. So it is very easy for them to create a clean virtually seamless box around and over their engines. They can create the box first, with the hole for the wiring harness in a set spot and then hook everything up with the proper length wires, hoses, linkage etc. Been there, done that got the 'T'-shirt. .



Greg L The Noise Nazi

 

[Lsfarm]

Valve cover blanket

Hi CM, yes the very first attempt to quiet down my engine was to cover the valvecover with a layer of a 1" thick dense foam I found at a car/truck parts swap meet. I was surprised and disappointed to find virtually no change in engine and in cab noise levels. I think there is so much noise radiating from the engine that just the valvecover blanket's effect wasn't noticable. Now when I remove the valvecover blanket with so much more of the engine insulated I can tell a noticable difference.



I didn't own a Db meter at that time, so I don't know just how effective the first attempt was. I just kept adding more blankets and covered more places untill I noticed a drop in noise.



I made an oilpan blanket out of the same foam, and it made a huge difference, then I started on the firewall. Most of my firewall is covered with my 'first generation' foam. I haven't taken the time to remove it and install the GSI soundstop foam, even though I know and have measured that it is better at blocking sound. The task of redoing the firewall takes a lot of motivation.



I learned about GSI from TDR member BCFast in Florida. and I learned about Lead Sheet from Goober in Ontario. I haven't tried 'Noise Killer ' yet, and I haven't insulated my door panels yet. I'm sure I have a lot more to learn from the TDR crowd.



I have replaced all the engine blankets with the much more effective GSI foam, and added a layer of it to the rear wall, and under the carpet and behind the kick panels.



My truck is quite tolerable now, it certainly is not as quiet as an '03, but I would say maybe half way between an '02 and '03.



Hope this helps, Greg L the Noise Nazi

 

[Sageair]

Greg: could you please tell me more about the GSI product? What is it and where do I find it? Thanks Steve

 

[GLASMITHS]

ATP Valve Cover Blanket

Now to the subject. Sometime back I purchased the subject cover. It is well made and heavy. After installing, I cannot tell the difference; however, since I have bi-lateral deafness (severe) that doesn't mean much. So asked the wife. So, she say that before the install she knew exactly when I pulled out of the driveway and could tell it was me before turning in.



Now after the install - she cain't hear the truck unless the door is open.



Perhaps that is overstating things, and it is kinda pricy; and the way Greg did his is probably better and a whole lot cheaper. But a point none the less. A lot of noise comes out of the valve cover.



Also, I installed the exhaust wrap e-brake down. Wife said it made a lot of difference? Additionally, there is 4 roll of sound stop in my garage, and will be 1 gallon of sound killer go on first, after removing everything from cab and doors. Also up the firewall as far as possible inside, and the outside (in engine comp).



Greg - I read somewhere a guy welded small strips of metal to exhaust pipe. Said it helped the drone?

 

[Lsfarm]

GSI and Drone

Hi Sageair, the site address is www.soundstop.com they are in Ft Lauderdale Fl. Make sure you mention the TDR club, I negotiated a 15% discount for us.



The soundstop foam has a shiney mylar surface on one side, and comes in various thicknesses. the 1/2" seems to work best for me. The foam has a barium rubber layer in it that blocks the sound. Baruim is very near as heavy as lead, I think this foam weighs about one pound per square foot.



Hi Glassmiths, I've heard of the same 'fix' for the exhaust drone. The exhaust pipe noise I'm refering to is a lot less noisy than the 'Dreaded Drone' I had the dreaded drone with one exhaust setup I tried, and it was awful !! I thought the windows were going to crack in the truck! I just changed the hanger locations and preload to stop the pipe from ressonating and droning. I know some folks have a regular drone poltergeist in their exhaust system, and have resorted to rather extreem measures to exorcise the noise



Take care, Greg L the Noise Nazi

 

[Tomscreek]

I'm still not clear on what noise you guys are trying to mitigate. I have an 01 and it's noisy when driving through a drive up window especially if there's a wall next to it. I always have to shut my truck off. It's just plain noisy when I start it and drive off when it's cold out. However when it's up to operating temp and I'm cruising down the highway at 2000 - 2200 rpms with the windows rolled up I think it's very quiet. It's also noisy if driving it in town with the windows rolled down. Does anyone else agree with me? I'd like to have it quieter in those above mentioned circumstanses too but those situations account for such a small percentage of the driving time, I don't know if it's worth it. The majority of the time I spend in the cab of this thing, I'm cruising down the highway and I really don't hear any noise.

 

[cmckinney]

I don't think my truck is quiet rolling down the freeway. Now maybe you can say that about a Mercedes or Lexus but not our trucks. I like to hear my engine as long as it isnt' deafening. The road noise I could do without.