I installed a 3/4-inch thick aluminum/mylar coated foam insulation pad which has a layer of mineral loaded sound barrier material. It's called Barrier 104.

I improvised some nylon screws and nylon nuts with fender washers as fasteners which utilize the channels in the steel hood braces, and also attached it with 3M Super Trim Adhesive. It's kind of heavy, and the adhesive has come loose in a few places, but I've been overall pleased with it. I've had it installed for over 10 years. The coating is fairly resistant to oil, but can get holes or tears easily. There is an aluminum/mylar tape available for repairs. The fasteners shown a few posts above would probably work for it as well. I used 3M Adhesive remover and cotton rags to remove most of the old adhesive.

Read more about it here: https://www.hamiltonjet.com/global/node/170, and here: https://www.hamiltonjet.com/global/node/25

Barrier 104 is shown in the second link.

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Marshall Welch
Seattle, WA
1982 300D-T

It is expensive. I’ve been looking for a generic one for sometime and haven’t found one yet but I’m sure it’s out there. Let us know if you find it.

Side note:
Weld nuts are another option instead of elevator bolts. The latter are hard to come by any smaller than 1-4-20.

Marine stores like West Marine and Defender usually carry that sort of insulation. But at marine prices

There is always Amazon: https://www.amazon.com/engine-compartment-insulation/s?k=engine+compartment+insulation But I wouldn't think the butyl type would stand up to the temperatures under hood.

For now, I am using the "do nothing" approach. Really don't notice much difference. Noise escapes everywhere, not just from hood

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

https://www.amazon.com/high-heat-spray-adhesive/s?k=high+heat+spray+adhesive

The pad isn’t there for noise insulation so much as to protect your hood from the engine heat.

There was a thread here about 10 years ago on this very subject. The conclusion that I recall being reached was using water heater insulation blankets available at Home Depot and similar. They used a spray on glue from 3M. Great thread if it's still available.

Some pads have a heat shield above the turbo. Read somewhere that they were only needed for California cars? Turbo more exposed?? Air cleaner seems to act as a heat barrier on my 85.

Bob338 - I did see this earlier thread. Sort of like HWH insulation. Not sure how effective it would be though.
New Under-Hood Insulation

It would be interesting to get some of that temperature tape and see just how hot the underside of the hood gets.

https://www.testo.com/en-US/products/temperature-measuring-strips

https://www.coleparmer.com/c/temperature-labels

I have used these in distant past on cars - maybe checking rad/coolant temperatures or manifolds. I forget. Can't recall where I got them, but they were not expensive.

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

On a similar note regarding noise and heat insulation I just remembered something and it may work for the hood as well.
The Interior firewall insulation On my ‘78 was crap. I’m not sure what they used but it looks like some sort of tar saturated roofing tile. It’s cracked apart and came out in pieces with ease. Anyway several years ago I completely lined the floor and firewall of my pickup using contact cement and those EVA tiles sold in 2’ x 2’ squares that link together. It’s intended for floor mat work/play areas but I use it everywhere I need padding. My pickup is a ‘91 Dodge Cummins. Noise and thermal insulation inside the cab is a necessity and that foam did an amazing job for both. It’s relatively abrasion resistant. They use it in shoes and even make lightweight sandals from it(Crocs). I laminated flooring vinyl over it for an extra layer of protection and it’s held up great. The contact cement odor was short lived and seems to hold up well to heat. You need to brush or roll a couple of coats on the foam because the backside soaks up the first.
A gallon of contact cement was about $30 and the foam mats are sold in stacks of 4-6 depending where you get them. Home Depot has the better quality 4-pack for about $20. They are thicker and denser than the 6-pack I got at Harbor Freight which do not mate with the H-D ones despite appearances. You can easily cut the tiles to any shape with a sturdy set of shears or straight edge and utility knife. Lots of uses for those pads. I even laminated knee pads to the outside of my coveralls for work. The coveralls wore out before the pads and I’m on all four much of the day working on boats.

I did mine a number of years ago. As I recall, I put the hood vertically up, laid a wooden plank across the width of the fenders so that I could either kneel or stand straight up next to the hood to clean off the residue hood pad and glue.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Wool will withstand the heat! https://www.thegreenage.co.uk/advantages-sheep-wool-insulation/

Make your own out of old army wool blankets?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Wool will also absorb every bit of oil, fuel , coolant or other vapors it can....

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Then burn like a Coleman stove if ignited.

Yeah I was going to say that I see more cars on Craigslist with the paint or clearcoat peeling on he hood right above the turbo.

I insulated my 300d recently just as a stop gap effort to protect this zone with 2 square feet of insulation right above the turbo. I will do the entire hood later. I had some leftover bubble wrap with Mylar coating left over from one of my other cars but not enough to do the entire hood. I always use this stuff because I am cheap and this stuff is available at Home Depot. I attach it with 3M F77 sprayment. The glue doesn’t stick forever. I just repeat spray the saggy bits every two years. Takes 30 seconds. Don’t forget to turn your can upside down and spray to clear the nozzle and lift tube or you’ll be buying a new can every time.

This is the insulation I use. I know, not for purists but I’m a cheapskate and I’m just trying to save myself a paint burn at the turbo.

Bought in a roll or by the yard at Lowe’s, Home Depot or ACE. Cheap.



Not the greatest photo but you can see my little patch of Mylar under the hood. Strategically placed to protect the hood from the turbo.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

So will any other hood pad.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

It was 2013 that I installed my hood pad! It is doing just fine. I snapped a pic of it this morning.

Attached Thumbnails

 

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked