1984 300SD engine compartment hood insulation

The old black foam insulation stuck to the underside of the hood turned to dust with a finger poke, and some of it was missing. A friend mentioned that without the insulation, the heat from the engine would cause the paint to quickly fail on that spot of the hood.

I went to Lowes and got a roll of aluminiumized Mylar bubble sandwich insulation. I needed a 3-foot wide roll to do it in one piece, so naturally I had to buy the 4' x 25' roll for $43. I rationalized it by saying, that's enough to do it 4 times to get it right, and it costs about the same as the replacement insulation from the auto parts store.



The hood came off the car pretty easy with a helper. I unplugged the wires to the squirter heaters, and the feed tube for the squirters. The clips and pins came out of the hood hinges easy. Be careful not to drop the back edge of the hood onto the windshield as you remove it. There is a trick when reinstalling the hood pins. Two of them have a bump under the head of the pin that fits into a detent in the pin socket. Turn the pin so those line up or you won't fully seat the pin or get the retaining clip on it.

I put the hood shinny side down on a folding table with blankets for padding.

I used a plastic scraper to remove most of the old foam. It came off easy and smelled strongly of diesel saturation. The big pieces when straight into a nearby trashcan. The 5 gallon shopvac came in handy to suck up the smaller bits and dust and avoid a mess.

I used a 3-inch razor scraper to clean most of the old glue and remaining pad off the metal.

I rolled out the bubble insulation and cut it large. I slowly and carefully trimmed it to the shape of the front of the hood so that it would tuck under the lip. As I worked my way around, trimming it bit by bit I kept tucking it under the lip. This kept it from sliding around so it was easy to make accurate cuts.



When I got on the down-sun side of the hood, it was way too bright with the sun in my eyes, reflecting off the insulation, so I rotated the hood to be working on the up-sun side again.

After the piece was fully trimmed and tucked into the lip, I carefully untucked the front half of the insulation and folded it up 90 degrees. I sprayed 3M contact cement in the middle area of the hood and up on the insulation, avoiding getting it too close to the edges. I waited about 10 seconds for the cement to start getting tacky and carefully lowered the insulation onto the hood trying to avoid wrinkles, and tucked the edges back under the lip. I took a break for about 10 minutes to let the glue set.

Then I untucked the back half of the insulation and repeated the glue process.



I'm fairly pleased with how this project turned out. There are some small wrinkles, but nothing serious. What I like best about this type of insulation is that when a fuel line pops off, it won't get saturated with diesel, like the foam does.

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.
1st MBz: 1982 300SD
2nd MBz: 1987 300SDL
3rd MBz: 1995 S420
4th MBz: 1987 190DT
5th MBz: 1984 300SD w/1983 300DT engine
6th MBz: 1999 C230k I'm 3rd owner, got it w/57,235 miles.
and manages Mom's 2007 R320 CDI

I would like to know how well this holds up. My concern, due to the heat locally, was the underlying hexcell construction was made of plastic. However, it the mylar sufficiently reflects the heat, this may not be an issue.

I agree, the foam pad has to be replaced about every 2-3 years around here and much less if it ever absorbs diesel fuel.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

Also interested in how that will hold up. My story- I installed a sheet of aluminum-mylar coated thick foam I bought from a marine supply company. It has a mineral-loaded barrier layer sandwiched in between two layers of foam.

It works well, but it's heavy. After a few months, it started to come loose, so I removed it, and re-applied adhesive. The second time, I used 3M Super Trim adhesive to hold it on, and that works better than the 3M Super 77 Adhesive did. I've had it on for about 5-6 years now- it's holding up well.

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Marshall Welch
Seattle, WA
1982 300D-T

Spacey

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Shiney.

I remember that a local guy (1project2many) used old carpeting for his hood insulation pad. It looked quite good. And free.

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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

You really need flashing of some sort over the turbo area!

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Why? The whole thing is covered by a layer of aluminum/ mylar flashing.

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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 melts at 250C....

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

I got a roll of aluminized felt made of recycled blue jeans by Logi-tech or something like that at a rummage sale for $2. I applied it to the underside of my hood without removing the hood using spray glue meant for cloth (CRC that i got at harbour freight).

Seemed to go on pretty well, hope it holds up!

What is "it"?

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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

Mylar. If its got such a low melting point, I'll just assume deterioration stats sooner than that. Might be as simple as just a square of some decent aluminum foil.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Gold coated Mylar was used to reflect heat off the Lunar Lander in the 60s and 70s. The walls of the crew compartment were as thin as an aluminum can.

__________________
.
1st MBz: 1982 300SD
2nd MBz: 1987 300SDL
3rd MBz: 1995 S420
4th MBz: 1987 190DT
5th MBz: 1984 300SD w/1983 300DT engine
6th MBz: 1999 C230k I'm 3rd owner, got it w/57,235 miles.
and manages Mom's 2007 R320 CDI

Good answer. 250C is near 500F, unless you idle a parked car on a hot summer day for hours at a time, should not be an issue.

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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

I've looked all over lowes.com and can't find this material. Any idea what Lowes SKU and/or Item Number is?

It's called Reflectix. Item# 13353

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )