M939 Series Hood Insulation

[Cruceno]

Well that's disappointing. I fully recognize that you won't be able to turn the thing into a silent hybrid, but I had hoped that it would at least make a noticeable reduction in the noise level.

 

[aheilmann68]

You and me both. At the very least it cut down the higher frequency noise. I think the greatest gains are sound deadening the cab, especially since I have the hard top.

 

[Trailboss]

Let us know how it works out for you. I looked over that stuff (and a few others) but I shied away from it because of the relatively low temperature rating. A0/A1 engines operate at 175-195*, and A2's at 190-200*. The link you posted rates that insulation at 225*. I'm concerned that engine heat coupled with summer temperatures would lead to a failure of the insulation.

Maybe I'm being too cautious? Anyone else have any thoughts on this?

The engine coolant temperature is what the gauges measure. Temperatures in the engine compartment, especially the exhaust manifold, may be a couple of hundred degrees higher. At work, our water-cooled natural gas compressor exhaust temperature is normally 600-700 F, but I've never measured a diesel exhaust.