What type of adhesive for engine room insulation?

[Dan_Y]

Our h36 has nice foil/Mylar wrapped closed cell foam (appears to be anyway) in 1 inch-thick sheets lining the engine compartment. I had to pull part of the foam to access fasteners. The adhesive is amber/brown color and still flexible and it's pretty difficult to separate the insulation from the wood. The insulation does not have the Mylar on the back (bonded) side, and so the adhesive directly bonds the grey foam to the wood.
Any recommendations for adhesive? The adhesive reminds me of spray-on gasket, like permatex, but I doubt that it is. The stuff hunter used in 2008 is really good and tenacious.
Thanks, Dan

 

[Brian S]

there was once an article about insulating an engine compartment in Good Old Boat magazine. I guess about a year, year and a half ago? Sorry can't give you more definite. I thought about keeping old magazines for reference purposes, but realized I never go back and look at them, so I started tossing them.

 

[Whatfiero1]

3M spray adhesive

 

[justsomeguy]

3M spray adhesive

And some metallic duct tape for the corners/joints.

 

[Dan_Y]

Thanks - I'll give the 3M a try. In our '91 h30 the insulation was stapled but didn't look as thick or as good as whats in the '08.

 

[SG]

There is usually a metal fastener system:
https://www.jamestowndistributors.com/userportal/woeimages/howtos/1072e.jpg

 

[JamesG161]

And some metallic duct tape for the corners/joints.

I dumped my OEM insulation and used this 2" board with guess what
"Duct Tape" or metallic type (which is used)

https://dcpd6wotaa0mb.cloudfront.net/mdms/dms/EIS/57577/57577-QuietR-Duct-Board-Data-Sheet.pdf

You can use the adhesive too, but I didn't.

I also built a sound enclosure for AC unit and genset with this Duct board.
Jim...

PS: I got all free from my AC contractor.

 

[justsomeguy]

There is usually a metal fastener system:
https://www.jamestowndistributors.com/userportal/woeimages/howtos/1072e.jpg

That makes good sense on the ceiling area, definitely.

Did the OP have to pull the ceiling?

 

[Dalliance]

I would test the adhesive on a small area first to see if works and doesn't something unexpected - like dissolve the foam insulation. The mechanical fasteners that SG suggested are a good idea. Use duct tape at the edges or any cuts or tears. In fact, duct tape alone may do the job for you.

For what it's worth -- When I replaced my insulation a few years ago, the new insulation had a peel and stick adhesive on the back. I think the original insulation was probably the same. Spent a lot of time removing the old adhesive with a citrus oil based goo-off type product (can't recall the name off hand), then MEK to remove the oil from the plywood. Used the mechanical fasteners, in addition to the peel and stick adhesive on the ceiling and the back side of the lift out companionway steps, also at the top edges of the vertical surfaces.

 

[SG]

The effectiveness of adhesive alone is challenged by heat in the engine compartment, the state of the surrounding enclosure's surface, vibration, and occasional human disturbances.

Reusing the existing adhesive or removing it would seem daunting to me.

 

[justsomeguy]

The mechanical fasteners that justsomeguy suggested are a good idea.

Credit @SG

 

[Dalliance]

Credit @SG

Oops. My apologies to SG.
Post corrected.

 

[Dalliance]

The effectiveness of adhesive alone is challenged by heat in the engine compartment, the state of the surrounding enclosure's surface, vibration, and occasional human disturbances.

Reusing the existing adhesive or removing it would seem daunting to me.

I would not suggest removing or re-using the old adhesive in this case. I may have confused the issue there with too much info about my own experience with a total replacement. Dan_Y just needs to re-attach the old insulation he had to peel off. Mechanical fasteners and/or duct tape should do the job. Spray adhesive? Maybe. Check it first.

 

[Dan_Y]

Thanks for the suggestions. Whatever the adhesive is, its really good. I'm thinking an auto parts store may have adhesives. I like the mechanical fasteners. There are others areas I want to insulate, like the hot water heater, which is under the main berth. Doesn't help in summer...will have to look for Jim's duct board.

Update: Saw article in this old boat where the author used contact cement to glue insulation to the hull. Will test a small spot soon since I have some on hand...

 

[william24424]

What if there was no heat insulation? Would that melt the fiberglass? Just curious.

 

[Dalliance]

What if there was no heat insulation? Would that melt the fiberglass? Just curious.

The engine room insulation is primarily for noise reduction; not thermal protection.

 

[Chief RA]

Yes, contact cement seems appropriate in this case. Chief

 

[SG]

Heat is the first issue. The sound damping insulation is heavy.

The second is that if you don't have a clean set of "flat" surfaces with contact cement you may not have the adhesion you need.

 

[Chief RA]

contact cement is still the best. The way to apply contact cement is let it set up on both surfaces and if it isn't an exact match like with flexible insulation just use a rubber mallet and tap it into contact with each other.all over the surface Chief