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Author Topic: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI  (Read 2650 times)

1997Adventurer30WQ

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How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« on: September 17, 2015, 08:22:12 PM »
Except when cruising at moderate speeds, there is a lot of engine noise and road noise in the cabin. Climbing hills is very noisy, even if they aren't a challenge for the drivetrain. The gasket for the "dog house" is in good shape, and the engine does not make a lot of noise, but the noise that it makes gets into the cabin. If any of you have modified a similar coach with sound insulation, what specifically worked for cutting down on the noise?

FYI, the engine runs great and has plenty of power, and is unmodified, except for missing the little cover for the air cleaner intake on the firewall. I intend to plumb a metal flex hose near to the grill to direct the intake noise from under the hood area. There is plenty of other noise to deal with besides the intake moan.

SeilerBird

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #1 on: September 17, 2015, 09:04:35 PM »
Get a DP 8)
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mypursuit

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #2 on: September 18, 2015, 12:18:16 AM »
Can't really help you on the noise problem except maybe the engine fan clutch is always
engaged.  That will definetly make a roar.
For the intake, go to Home Depot or Lowes and go to the roof gutter area.  You should find
a downspout adaptor about 30 inches long, round on one end ,square on the other.  Put
the round end in the hole and drill a small hole in the other end for a plastic tie wrap. Tie
it to the grill and you have homemade cold air intake!  Even come in different colors!.
1997 Georgie Boy Pursuit     2008 Ford Focus
P-30 / 454 Chevy w/ Stan's Headers, ceramic plug wires, cold air intake and K-N Air cleaner
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U.S. Navy 1970 - 1990
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driftless shifter

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #3 on: September 18, 2015, 10:43:28 AM »
We call that noise releasing the Wookie. You are hearing induction noise from the throttle body, it's probably extra loud due to the missing bits. I used a piece of this, cut to my appropriate length.
http://www.homedepot.com/catalog/productImages/400/67/67abf76e-676a-4aa0-98cb-cc34548143c8_400.jpg
and this
http://www.homedepot.ca/product/plain-reducer-6-in-x-4-in-26-galvanized/911776
Made my own cold air intake, It reduces noise some but not a lot. Next step, when I get time is to glue some sound deadener to the under side of my dog house cover. Front engine gasses are noisy.

Bill
Bill & Nan
(o\_!_/o)
93 bounder 34, chevy chassis
couple of aircooled vw's, 1 fast(sold), 1 reliable(sold).  Dubless : (
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Sam!

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #4 on: September 18, 2015, 11:28:09 AM »
Since Insulation mat peal and stick has gotten popular and cheaper. and for sure was not used as much back in the fabrication days of most of our older RV's.

Buy some and start seeing where you can apply it from the fire wall, inside of dog house, floor boards under carpet from firewall back to about above transmission area. 
1997 Serro Scotty 25' Diesel Cummins 4x4
2005 Dodge Ram 3500 Diesel SRW
2000 Tacoma Dezert trux
San Diegan

BoomerD

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Current coach: 2004 Winnebago Sightseer 30B

1997Adventurer30WQ

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #6 on: September 18, 2015, 09:04:11 PM »
SeilerBird: I guess that if you push my gasser with your DP, I could enjoy a much quieter cabin in my gasser, otherwise, if I just get a DP, my gasser will make exactly the same amount of noise that it makes now. ;D
Seriously, I will never want a diesel: the fuel stinks much worse than stinky gasoline, the exhaust stinks, they make much more noise outside of the cabin, maintenance is more expensive, and they cost much more up front. I will never drive enough to justify the extra initial expense, and will never want a really big MH that only a diesel drivetrain can handle. I would buy a newer gas coach if I wanted to spend lots of money, and pay for premium sound insulation materials and professional installation. I bought a cheap, old gasser because it made sense for my intended purpose, but it has more cabin noise than it should, IMO.

mypursuit: The fan is not always engaged, but it generates some noise that gets through to the cabin anyway. I will consider the option you suggested on the intake.

driftless shifter: I didn't think the sound is Wookie; more like a groaning zombie, maybe? The intake duct is only missing the little flat "cap" that goes over the intake duct at the firewall, but that might make a big difference for all I know. I would expect a duct to work better than the little cap. I have considered the galvanized ducting and the 6" to 4" adaptor, but I haven't tried to piece it together yet. I might also wrap the duct with insulation, like some cars have as original equipment.

Sam!: I have not found a reasonably priced product that appears to have enough sound absorbing/damping ability along with an adequate temperature rating for under the hood/doghouse. I have some one-inch-thick, "sound-absorbing," sticky-backed, foil-on-one-side foam that I bought from McMaster-Carr, but I don't think it will work well for noise suppression in the RV, nor do I expect it to hold up to the heat under the doghouse. It would work for keeping out heat when moving down the road, I think; but once the under-hood heat soaks into it when parked after running, I think the foam will break down. The McMaster catalog has some expensive silicone foam rubber sheet that looks like an excellent choice, but I don't want to spend several hundred dollars insulating the hood and doghouse. BTW, I will not rely on glue to hold insulation up off of the engine under the doghouse; I will fasten it somehow in addition to any glue to avoid contact with blazing hot exhaust manifolds.

I was hoping that someone could point to specific effective material(s) and the correct place(s) to install to get results.


BoomerD: I much prefer earmuffs, and I may use them if a long ride proves too much for my ears.
« Last Edit: September 18, 2015, 09:06:12 PM by 1997Adventurer30WQ »

Sam!

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #7 on: September 18, 2015, 10:31:53 PM »
spill guard carpet padding and install tested see this thread: http://www.cumminsforum.com/forum/94-98-non-powertrain/1175737-my-sound-reduction-odyssey.html
1997 Serro Scotty 25' Diesel Cummins 4x4
2005 Dodge Ram 3500 Diesel SRW
2000 Tacoma Dezert trux
San Diegan

legrandnormand

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #8 on: September 18, 2015, 11:23:16 PM »
1997 Adventurer, no wonder you think that diesel stinks by owning a 1997 gasser ! Today's diesel don't even poluate as your old gasser.
Evolution, do you know what that means ?  Today in 2015, you are polluting with your antique 454 GM engine and noisy also !
Normand
Trois-Rivieres, QC, Canada
2010 Gulfstream Independance, model 8367
2009 Smart Cabriolet

1997Adventurer30WQ

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #9 on: September 19, 2015, 01:55:38 PM »
Sam!: That is the info I am looking for. There are a bunch of great links within and connected to that forum thread. Thanks!

legrandnormand: Diesel fuel still stinks very badly, but maybe you know where to always get full service when refueling.  ;D
The '97 454 runs great, runs quiet, has less than 38K miles, and has fully functioning throttle-body fuel injection, emission controls, and exhaust catalyst, so it is still likely a bit cleaner running than a new 2015 diesel. Newer diesels still emit soot when under a heavy load and clatter all the time (although far less than older ones). I still push the recirculation button on my car's A/C controls whenever I am behind a pickup, truck, MH, or any other vehicle likely to have a diesel, even if it is newish, because they frequently stink and belch soot. If I start the old Chevy 454 in a campground, the guy next to me on the driver's side will probably notice, but likely no one else; start nearly any diesel, especially any DP, and everyone around for a hundred yards will likely know, and the soot and stink will belch out until it warms up. (I don't mean clouds of soot, but soot nevertheless.)

I did not start this thread with the intention of discussing the merits of a DP. I will never want one, and I will not likely ever be able to afford one. It seems to be the favorite wisecrack of DP owners to suggest that a DP is the solution to all MH problems/complaints. That's fine as joke, and my reply to that joke was another joke, and brief explanation as to why a DP is no solution for me, even if I have the money to spend. Please, no more comments about how great diesels are.
« Last Edit: September 19, 2015, 01:59:03 PM by 1997Adventurer30WQ »

kdbgoat

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #10 on: September 19, 2015, 02:03:21 PM »
Have you checked out stuff called Dynamat?
I know you believe you understand what you think I said,
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Mpyre

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #11 on: September 21, 2015, 06:01:12 PM »
I too have a screaming 454 in the doghouse.   I was more concerned about the heat than the noise when I decided to add some insulation.  The first thing I noticed was the noise reduction.  We can still definitely hear the Wookie\Zombie but much less than before the insulation.  I found these products at JC Whitney from another member post.  Install took ~2hrs and it seems to be holding up OK after traveling 2K miles.  Just be sure to clean the contacted surface well before application.

Part #: BND6010000200
 Bonded Logic 30-ft. Length Aluminum Tape
 Bonded Logic
 Qty: 1.00
 Price: $ 10.51

 Part #: THT14110
 Thermo-Tec Thermo-Tec Cool-It 14110 Heat Insulator, Yellow/Silver, Sold Individually
 Thermo-Tec
 Qty: 1.00
 Price: $ 72.15

 Part #: THT12005
 Thermo-Tec Thermo-Tec 12005 Adhesive Compound, Sold Individually
 Thermo-Tec
 Qty: 1.00
 Price: $ 24.93


1998 Fleetwood Flair 25'

1997Adventurer30WQ

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #12 on: September 22, 2015, 08:36:36 PM »
Mpyre:

That appears to be a very good choice for the engine side of the doghouse, floor, and firewall. There is a good chance that I'll use it because one web merchant selling the stuff claimed a rather high temperature rating of 400 F for direct contact, so it should not deteriorate quickly.

All:

After reading through some info on noise reduction for vehicles, I surveyed my Winnebago:

There is no insulation under or over (only carpet) the doghouse, under or over the floor, or on either side of the firewall. In the cabin area, there appears to be no sound deadening or sound absorbing material and there is no carpet padding. I have not checked for gaps and holes, but there may be some of those as well.

If you tap on the floor and firewall anywhere in the cabin area, it resonates.

How could you make noisier inside without actually generating more noise inside or out? No carpet, some holes, some gaps, and a metal dog house. Basically, Winnebago could not have done much less to stop noise transmission. Oddly, it has a double seal arrangement on the driver's door which will reduce wind and road noise in that area.

From the info that I have gathered, there is no point in using a Dynamat-type product on the doghouse since it is thick fiberglass and resists resonating. Apparently, such products only "deaden" a panel so that it does not resonate, and more than 50% coverage is nearly always a waste of money, although full coverage is what most of the retailers and manufacturers of similar products seem to be suggesting. Some Youtube video of "professionals" installing Dynamat are full coverage jobs, yet acoustical engineers claim that 25% to 50% is all that you ever need. Most of the rest of the noise reduction should come from inexpensive jute or foam padding and carpet, although layering some MLV (mass loaded vinyl) with sound absorbing padding (or a single product with combined materials) can get even more reduction with more expense.


My current plan:

I want to put some Dynamat-type product over part of the panels and floor that resonate, install heavyweight carpet padding over the floor and firewall on the inside where possible, seal all of the holes and gaps, insulate under the doghouse and adjacent firewall areas, and extend the duct to the engine air inlet. Since there is only some carpet over the floor and doghouse to isolate noise as it is, the changes I want should make a huge difference. The problem is that the materials for all of the changes together might be $400+, and there may be surprises like rusty metal under the carpet that would need to be cleaned off and painted. Re-fitting the carpet on the driver's side will likely be a pain because the floor is not completely flat, and the padding will change how it fits. I can already see that the doghouse insulation materials will cost $100+ for good temp-rated stuff. Sound absorbing material under the doghouse carpet should help, but I don't want to remove the carpet.


I still welcome input on this project.


quadrider

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #13 on: September 23, 2015, 03:44:37 AM »
Make sure you check the dog house where it mounts to the firewall. On my bounder I found the dog house on the left front corner by the gas pedal didn't bolt up tight against the fire wall. I could reach behind and there was a one inch gap that lead directly to the engine compartment between the dog house and engine shield. Only found it after a exhaust leak started and I could smell fumes in the RV while stop at a light.

1997Adventurer30WQ

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #14 on: September 23, 2015, 07:59:02 PM »
I just took my first look at gaps/holes between the cabin and engine bay and under the hood. Just after dark this evening, I got out a shop light and shined it near areas suspected to have gaps or holes, and I found some issues:

Fortunately, the doghouse should be fairly well sealed to its gasket since there appeared to be no light shining through around it.
There is a gap of perhaps 1/2" by 2" (can't tell for sure, but it is big) above the throttle pedal on the firewall.
There is a big hole, mostly sealed with tape, where some electrical cables pass through. The tape is no barrier to noise.
Adjacent to the hole mentioned above, there is a missing cover for the enclosure for those cables (and a couple of solenoids). Putting a cover back on will be an additional barrier to noise.

The rather large hole near the throttle pedal is probably why I hear the engine fan so much even though the fan is not "engaged." I'm sure it passes some intake noise as well.

It looks like I need to fabricate a cover (or two) and caulk some holes as a first step on this project.

Sam!

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #15 on: September 23, 2015, 10:11:57 PM »
I recently used these items without overthinking (An insulated panel is 100% better than a non insulated panel) their qualities to seal any and all holes and crack around and under my RV.

Expanding foam can.
Vulkem Caulk.
Extreme Weather HVAC Foil Tape.
Pieces of sheet metal and metal screen.

and you could use water pipe insulation foam around wire looms or firewall penetrations.
1997 Serro Scotty 25' Diesel Cummins 4x4
2005 Dodge Ram 3500 Diesel SRW
2000 Tacoma Dezert trux
San Diegan

Alfa38User

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Re: How to reduce cabin noise - 1997 Winnwbago P30/454 TBI
« Reply #16 on: September 24, 2015, 09:26:59 AM »
If you are looking at sound deadening products, look at you favorite marine store. There is no bigger sounding box than a boat's engine room. I lined my boat's engine cover (= RV engine dog house) with sheets of a leaded material and that helped but.... That huge sounding box was impossible to beat.
Stu
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