Engine Bay Insulation Recomendations

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Engine Bay Insulation Recomendations

August 27, 2017, 12:58:28 pm

It is time to replace all my engine bay insulation. Yes I have read and reread thread after thread on this subject until my eyes started bugging out of my head. And Yes I still need help choosing a decent replacement that won't break the bank. I greatly would appreciate brand and approx how much material I might should order. I'll get it ordered right up.

Re: Engine Bay Insulation Recomendations

Reply #1 – August 27, 2017, 01:03:14 pm

You are a better man than I. Ours was replaced just before we bought it, the outlet did a beautiful job. Not something I'd attempt!

Re: Engine Bay Insulation Recomendations

Reply #2 – August 27, 2017, 01:28:52 pm

Several years ago I bookmarked the thread below, because I liked to look of the product, and cuz several of the "smart kids" liked the product. Haven't gotten around to doing my engine compartment, but "it's on the list...".

reinsulated engine compartment

Re: Engine Bay Insulation Recomendations

Reply #3 – August 27, 2017, 02:23:14 pm

I will be joining you in two weeks. I used Soundown in the generator compartment and thought it did a good job. Where you purchase this is important because it is heavy and expensive to ship. Don recently posted that Bay Marine now carries it.

https://www.jamestowndistributors.com/userportal/search.do?refineType=1&sub_attr_name=Brand&refineValue=Soundown&page=GRID&engine=adwords&keyword=soundown&gclid=EAIaIQobChMIx5GAmoL41QIVDoFpCh2aig6SEAAYASAAEgJ2RvD_BwE

I am going to use Soundown again for the top of the hatch and thermo tec to cover and seal off the existing insulation on the sides. Adding a blanket for the turbo as well.

My order isn't in yet so measurements aren't finished. I used one kit plus a roll of tape and two additional adhesive cans for the generator compartment. That was in April and everything has stayed put so far.

Amazon.com: Thermo-Tec 14125 48" X 72" Two Sided Thermo Guard Flame Retardant...

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Engine Bay Insulation Recomendations

Reply #4 – August 27, 2017, 03:19:29 pm

This worked awesome. Went over old insulation:
Engine bay complete

Re: Engine Bay Insulation Recomendations

Reply #5 – August 27, 2017, 03:33:31 pm

Stump,
Just my thoughts on the subject (FWIF):

I redid mine over 12 years ago using the high dollar sound insulation. That's the stuff with 3 layers: 2 foam with what they call a "barrier" of dense rubber (they used to use lead) in between the foam. I used the variety with shiny "foil" on the outside so it reflects the heat of the engine. Heat and age are what will degrade the foam. Engine Compartment insulation

I'm not sure I would use it again. I couldn't really tell the sound level went down any. I think this wasn't due to the material not working but the application. I think the sound has other paths to get inside; the floor, walls, windows, rear cap, etc.

Another thing is air gaps. They will transmit a lot of noise. So make sure the bulb seal around the bed opening is in good shape.

So if I were to tackle this again I would focus on thermal protection first rather than sound. Maybe a layer of rigid foam (like from Home depot) topped with something that has good heat resistance. And since the turbo is so close to the bed deck (on U300s) maybe a piece of sheet metal as a heat shield for the turbo area if you don't have a blanket.

Re: Engine Bay Insulation Recomendations

Reply #6 – August 27, 2017, 05:22:49 pm

After fire testing the insulation and noticing how close the turbo is to the insulation above, I pulled it all off, installed Fiberglas insulation and then covered it all with HardieBacker. I primed the backerboard and then painted with a latex white semi-gloss. The paint keeps grease from being absorbed and allows easy cleaning. Fasteners are stainless screws and washers. A standoff is used between each screw and the plywood.

Another U300 was lost when the pipe came off the turbo from a shop's repair a day or so earlier and allowed the turbo exhaust to ignite the insulation. They were just able to stop and evacuate before the coach went up in flames. Until the fire burns through the wiring, the engine could care less if it's on fire so the coach may be on fire without the operator noticing it.

Use a box cutter to scribe the backerboard so no need to make dust. I did the same for the fridge compartment. The generator compartment is terrible and the flex exhaust had melted through the insulation and was against the plywood.

Here is the album with all the photos: Browser no longer supported

Pierce

Re: Engine Bay Insulation Recomendations

Reply #7 – August 27, 2017, 09:23:17 pm

Check out an commercial/industrial insulator who buys the boards by the truckload direct from john-mansville or Owens Corning. He may have a stack of special thickness, density, or temp rating boards he may like to unload.

Re: Engine Bay Insulation Recomendations

Reply #8 – August 28, 2017, 10:09:21 am

I am going with the Soundown stuff. I calculated just under 50sq. ft. for the engine compartment, and a bit over 20 sq. ft. for the generator compartment. Each sheet is 12 sq. ft., I bought 5 for the engine compartment to be sure that I won't have to splice in a bunch of smaller pieces, but I think 4 will actually do it. I will see how much I have left over before I get the stuff for the generator compartment. Not cheap, but it is quality stuff. On the Unicoaches, it appears there is more space above the turbo than on the Unihomes, at least the Detroit powered ones. I will eventually get the turbo cover anyway, but that will have to wait awhile.
Don

Re: Engine Bay Insulation Recomendations

Reply #9 – August 28, 2017, 10:34:52 am

Quote from: Don & Tys (AKA acousticart) – August 28, 2017, 10:09:21 am

I am going with the Soundown stuff.

Don,

Which "stuff" are you going to use? In Reply #3 above, the link shows two products. They have "Soundown Acoustic Absorption Foam" and "Soundown Composite Insulation Vinyl/Foam". The second one costs twice as much as the first. Not clear to me which one would be better in this application...

Re: Engine Bay Insulation Recomendations

Reply #10 – August 28, 2017, 11:04:02 am

I bought the Soundown Composite Insulation Vinyl/Foam. The foam by itself is not effective on low frequencies, the mass of the dense stuff in the middle is what can attenuate the rumble. Truthfully, I am not obsessed with eliminating the sound, as even without anything back there, it is not a problem going down the road, The latex foam mattress we have does good job of quieting her down by itself, but quieter is better... I think the radiant heat reflection will be helpful with the bedroom heating and you could get that without paying for the composite stuff, but the non composite acoustic absorption foam is apparently available in only half or one inch thicknesses, but there is other stuff that could be found. I just wanted to use something engineered for this purpose that will give me pleasure every time I pop the hatch. The angle iron mattress platform support is an inch and a half, so I am using the inch and a half thick stuff for the engine compartment to make it flush with the edge of the angle iron. I will probably use the same in the generator compartment. The old stuff that I removed was beyond encapsulation, so I terminated it with extreme predjudice.

Don

Quote from: Chuck & Jeannie – August 28, 2017, 10:34:52 am

Don,

Which "stuff" are you going to use? In Reply #3 above, the link shows two products. They have "Soundown Acoustic Absorption Foam" and "Soundown Composite Insulation Vinyl/Foam". The second one costs twice as much as the first. Not clear to me which one would be better in this application...

Re: Engine Bay Insulation Recomendations

Reply #11 – August 28, 2017, 11:10:26 am

Did two generators with this stuff, not very expensive and can get on amazon.
FatMat Sound Control Xtreme Floor Liner

Re: Engine Bay Insulation Recomendations

Reply #12 – August 28, 2017, 02:38:55 pm

#3 AKA George. FWIW I listed both so the options were present to see all offerings. I used the more expensive product kit for the Gen set. Almost nothing left over in the 24 sq ft foam. I did cut and place together the pieces as it comes with two sheets of 1 inch. The difference is notable and the powdering OEM is no longer a mechanical or fire hazard.

Re: Engine Bay Insulation Recomendations

Reply #13 – August 28, 2017, 04:23:35 pm

I went w/the Hardie board - Hat tip and thanks to Pierce for the idea. For < $40 I did the entire compartment. Note: The area around the exhaust - where it vents down to the muffler - evidently got very hot in my rig. The little plastic fender washers that held the old insulation were all melted into little balls.. This is what it looks like now. -Nick

Re: Engine Bay Insulation Recomendations

Reply #14 – August 28, 2017, 04:45:43 pm

Quote from: lunker – August 28, 2017, 04:23:35 pm

I went w/the Hardie board - Hat tip and thanks to Pierce for the idea. For < $40 I did the entire compartment. Note: The area around the exhaust - where it vents down to the muffler - evidently got very hot in my rig. The little plastic fender washers that held the old insulation were all melted into little balls.. This is what it looks like now. -Nick

Thanks. Nice clean job! I can't imagine anything better than Hardie. Even though it's only 1/4", you can't burn through with a cutting torch. The OEM exhaust on the generator sure could use a re-design. I would like to figure out a way to be able to use the slide feature but get rid of the flex pipe.

Pierce

Re: Engine Bay Insulation Recomendations

Reply #15 – August 28, 2017, 05:28:47 pm

Well started my reinsulation on my engine bay. Not too bad a job. It was dirty, but got it done and everything cleaned up. Next will be degrease engine and radiator. Called a place in Mooresville, NC that sells the heat insulation for the race cars. Product has a 2000 degree rating. He said come on by they have piles of used material I could pick through. Or I can buy new, stuff is 29.00 a linier foot. I guess the NASCAR guys redo this stuff often . I'll check it out for sure.

Re: Engine Bay Insulation Recomendations

Reply #16 – August 28, 2017, 06:07:43 pm

We covered original black film / foam insulation with Cool It Thermo Tec Thermo Guard. We used the two sided foil, purchased from Amazon and did engine and generator and after several years it is holding up very well. Held in place with some spray glue, aluminum tape & plastic fender washers.

Re: Engine Bay Insulation Recomendations

Reply #17 – September 02, 2017, 06:13:42 pm

After Lots of looking and comparing Im gong to go with the Cool It Insulation. 3# 48x48 sections should do it. It has a 2000 degree heat rating and I will use metal fender washers in the high heat areas. The Turbo is real close to the bed board cover and I may use another high heat section right there maybe. We'll see how it comes out.

Re: Engine Bay Insulation Recomendations

Reply #18 – September 02, 2017, 06:55:55 pm

Stump,
My thinking is that since the Cool It is only 1/2" thick, why couldn't it be place right over the old stuff. I think it's do able without having to disturb the old stuff.
John M.

Re: Engine Bay Insulation Recomendations

Reply #19 – September 02, 2017, 07:42:10 pm

We replaced ours last year after removing all the old foam OEM stuff. We used 1-1/2" foil backed high density fiberglass insulation from McMaster-Carr. (9351K2 ). Also used foil tape on the joints. The whole project occupied most of our day but the results were worth it! Not sure if its much quieter but it is cooler in the bedroom after traveling and the appearance alone is worth the investment.
Total cost was about $225 IIRC.

EDIT: uploaded the photos again, higher resolution, sorry about the low resolution thumb images

Re: Engine Bay Insulation Recomendations

Reply #20 – September 02, 2017, 07:42:42 pm

Old stuff is gone Starting from Scratch.

Re: Engine Bay Insulation Recomendations

Reply #21 – September 02, 2017, 07:50:34 pm

John M, We used Thermo-Tec dual sided foil over ALL engine and generator compartment's original thick black foam with the thin mylar/plastic coating. This original foam has imbedded 'lead' sound proofing material. Installing Thermo-Tec was to protect the original foam and to give the compartments a better water resistance covering. All seams, corners, tops & bottoms are sealed with a lot of foil tape to protect Thermo-Tec inner insulation. Spray glue, plastic washer/screws and lots of foil tape keep it in place. Everything is holding up for over 5 years.

Re: Engine Bay Insulation Recomendations

Reply #22 – September 02, 2017, 08:45:13 pm

Quote from: stump – September 02, 2017, 07:42:42 pm

Old stuff is gone Starting from Scratch.

I agree Stump, sometimes its just too far gone to be worth saving. Ours was shot, so out it went!

Re: Engine Bay Insulation Recomendations

Reply #23 – September 04, 2017, 02:04:31 pm

As time goes by the old stuff is still going to get harder and sift thru the cracks and end up on top of the engine,even if it does not
you'll have more of a gap and the new stuff will look wavy.

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