Engine noise

When I first bought my MH it was loud and hot on a hill climb. I added a 1/2 layer of insulation that I bought at HD or Lowes. It was inexpensive and worked well. I used Weldwood contact adhesive to bond the insulation to the factory insulation which was a bubble wrap material with foil on one side and about 1/4 thick. The new material was made from a jute felt and foil on the eng side. There was a huge reduction in noise and heat for about $20 of materials. Lead sheeting would be about the best material to use if cost was no object or you had a free or inexpensive source for it. We used to use a material called Acousticore where I worked which was a 1/2 in thick honey comb core with a fibrous material stuffed inside the cells of the core but found that .050 sheets of lead worked much better.

read on this, works great, Amazon is usually the cheaper place. Have installed it on all three Rv that we have had, and very good for road noise also.

http://www.dynamat.com/

Also make sure the gasket between the cover and floor/firewall is good.

Very satisfied with this product. Used Weldwood HI-temp spray adhesive to hold it on.

wow...gas card...500.00..on the monthly give away

Dare I say Thorley Headers? My coach got quieter at cruise once I installed them. The trick is that they must be heavy gauge steel, otherwise they will be louder than manifolds. My engine noise is just below or equal to the wind noise. There is carpet and one layer of acoustical asphalt sheet over the fiberglass engine cover. Here is a short video of a half throttle acceleration and cruise. Once it gets up to speed, the engine noise is below the wind noise.
http://s213.photobucket.com/user/Daveinet/media/Engine/Accelerateandcruise2_zps1c7df742.mp4.html

Lots of good suggestions above, they covered most everything.
Reducing that noise is mostly doing little bits, making every area as good as you can.

You didn't mention the age or engine in your motorhome?

Many are known to break manifold studs, or crack exhaust manifolds. Exhaust leaks = extra noise.
Some, particularly early Ford V10's, sometime blew out sparkplugs. A v10 running on 9 with an open hole would be very noisy.

Fan clutch... Your engine fan should have a good functional thermal clutch. You'll hear the fan when the clutch engages, which will be when you are working her hard and the temp rises a bit. If you hear the fan all the time, a new clutch will quiet things considerably.

And finally... the '99 V10 we used to have was horribly noisy. It also was extremely rpm happy, downshifting and reving high at the sight of a hill in the distance. I put in a tuner from Brazel's, and the difference was AMAZING! More power, better torque at low rpm, and no more downshifting. She'd hold in high gear much longer, and keep the rpms lower much of the time. This made a huge difference.

Then I fixed it for good. Traded for a DP.

The best results come from using 2 different layers.

I put this on the bottom of the doghouse first and then covered it with this.

They made an amazing difference.

If I was doing it again, I would use this first instead of what I used (it wasn't available when I did mine). The stuff isn't cheap, but it will be money very well spent-----------and if you can afford the gas for the MH, you can afford making it quiet.

The poor man's fix : Ear plugs, and turn your radio up! I'm just kidding! You need to insulate your dog house as op's have suggested!

JimM68 wrote:
Then I fixed it for good. Traded for a DP.

Yup, that will do it.